View Filing Data

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Segment Information (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Contract revenues	$ 188,847	$ 154,907	$ 154,907
Operating income (loss)	6,594	6,786	6,786
Intersegment revenues		(1,312)
Foreign [Member]
Contract revenues	38,385	18,025
Dredging [Member]
Contract revenues	173,959	123,673
Operating income (loss)	19,000	4,899
Demolition [Member]
Contract revenues	14,888	32,546
Operating income (loss)	$ (12,406)	$ 1,887
Parent Company [Member]
Operating income (loss)			$ (512)

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 6,643	$ 24,440
Accounts receivable-net	141,250	149,142
Contract revenues in excess of billings	73,916	69,574
Inventories	26,629	28,726
Prepaid Expense and Other Assets, Current	40,479	41,808
Total current assets	288,917	313,690
PROPERTY AND EQUIPMENT-Net	347,740	346,540
GOODWILL AND OTHER INTANGIBLE	103,967	104,031
INVENTORIES-Noncurrent	36,423	37,392
INVESTMENTS IN JOINT VENTURES	6,457	7,047
OTHER	17,509	17,695
TOTAL	801,013	826,395
CURRENT LIABILITIES:
Accounts payable	88,624	123,082
Accrued expenses	40,561	38,490
Billings in excess of contract revenues	9,529	11,280
Current portion of long term debt	2,526	13,098
Total current liabilities	141,240	185,950
7 3/8% SENIOR NOTES	250,000	250,000
Line of Credit Facility, Amount Outstanding	21,500
DEFERRED INCOME TAXES	103,436	106,767
OTHER	10,252	10,253
Total liabilities	526,428	552,970
EQUITY:
Common stock-$.0001 par value; 90,000 authorized, 59,359 and 58,999 shares issued and outstanding at December 31, 2012 and December 31, 2011, respectively.	6	6
Additional paid-in capital	272,156	271,418
Retained earnings	3,024	2,591
Accumulated other comprehensive income (loss)	(369)	(380)
Total Great Lakes Dredge & Dock Corporation equity	274,817	273,635
NONCONTROLLING INTERESTS	(232)	(210)
Total equity	274,585	273,425
TOTAL	$ 801,013	$ 826,395

Consolidated Statements Of Comprehensive Income - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2013

Mar. 31, 2012

Consolidated Statements Of Comprehensive Income [Abstract]

Net income

$ 411

$ 953

Currency translation adjustment-net of tax

^[1]

(6)

Reclassification of derivative gains (losses) to earnings-net of tax

(137)

Net unrealized gain on derivatives-net of tax

^[2]

474

Other comprehensive loss-net of tax

478

Comprehensive income

422

1,431

Comprehensive (income) loss attributable to noncontrolling interests

115

Comprehensive income attributable to Great Lakes Dredge & Dock Corporation

$ 444

$ 1,546

[1]	Net of income tax (expense) benefit of $(4) and $3 for the three months ended March 31, 2013 and 2012, respectively.
[2]	Net of income tax benefit of $11 and $315 for the three months ended March 31, 2013 and 2012, respectively.

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

Amount after tax, before reclassification adjustments, resulting from the process of expressing in the reporting currency of the reporting entity those amounts that are denominated or measured in a different currency, and from transactions whose terms are denominated in a currency other than the entity's functional currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=6915805&loc=d3e32211-110900

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (a-c)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6915805&loc=d3e32022-110900

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=6915805&loc=d3e32157-110900

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 17
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 52
-Paragraph 13, 20, 31
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Net of tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e689-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 24
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 18, 19
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 31, 46
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Net of tax amount, before reclassification adjustments, of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 17, 20
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 121
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 46
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 24
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4K
-URI http://asc.fasb.org/extlink&oid=18733213&loc=SL4591552-111686

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4J
-URI http://asc.fasb.org/extlink&oid=18733213&loc=SL4591551-111686

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 29
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 5
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph A1, A4, A5
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Consolidated Statements Of Equity (Parenthetical)	3 Months Ended
Consolidated Statements Of Equity (Parenthetical)	Mar. 31, 2012 $ / shares
Consolidated Statements Of Equity [Abstract]
Dividends declared per share	$ 0.02

Commitments And Contingencies	9 Months Ended
Commitments And Contingencies	Sep. 30, 2012
Commitments And Contingencies [Abstract]
Commitments And Contingencies	8. Commitments and contingencies Commercial commitments Performance and bid bonds are customarily required for dredging and marine construction projects, as well as some demolition projects. In September 2011, the Company entered into a bonding agreement with Zurich American Insurance Company (“Zurich”) under which the Company can obtain performance, bid and payment bonds. Bid bonds are generally obtained for a percentage of bid value and amounts outstanding typically range from $1,000 to $10,000. At March 31, 2013, the Company had outstanding performance bonds valued at approximately $612,677; however, the revenue value remaining in backlog related to these projects totaled approximately $186,754. Certain foreign projects performed by the Company have warranty periods, typically spanning no more than one to three years beyond project completion, whereby the Company retains responsibility to maintain the project site to certain specifications during the warranty period. Generally, any potential liability of the Company is mitigated by insurance, shared responsibilities with consortium partners, and/or recourse to owner-provided specifications. Legal proceedings and other contingencies As is customary with negotiated contracts and modifications or claims to competitively bid contracts with the federal government, the government has the right to audit the books and records of the Company to ensure compliance with such contracts, modifications, or claims, and the applicable federal laws. The government has the ability to seek a price adjustment based on the results of such audit. Any such audits have not had, and are not expected to have, a material impact on the financial position, operations, or cash flows of the Company. Various legal actions, claims, assessments and other contingencies arising in the ordinary course of business are pending against the Company and certain of its subsidiaries. These matters are subject to many uncertainties, and it is possible that some of these matters could ultimately be decided, resolved, or settled adversely to the Company. Although the Company is subject to various claims and legal actions that arise in the ordinary course of business, except as described below, the Company is not currently a party to any material legal proceedings or environmental claims. The Company records an accrual when it is probable a liability has been incurred and the amount of loss can be reasonably estimated. The Company does not believe any of these proceedings, individually or in the aggregate, would be expected to have a material effect on the Company’s results of operations, cash flows or financial condition. On August 26, 2009, the Company’s subsidiary, NASDI, LLC (“NASDI”), received a letter stating that the Attorney General for the Commonwealth of Massachusetts is investigating alleged violations of the Massachusetts Solid Waste Act. The Company believes that the Massachusetts Attorney General is investigating illegal dumping activities at a dump site NASDI contracted with to have waste materials disposed of between September 2007 and July 2008. Per the Massachusetts Attorney General’s request, NASDI executed a tolling agreement regarding the matter in 2009 and engaged in further discussions with the Massachusetts Attorney General’s office in the second quarter of 2011, but has had no further contact with the Massachusetts Attorney General’s office since then. The matter remains open, and, to the Company’s knowledge, no proceedings have currently been initiated against NASDI. Should a claim be brought, NASDI intends to defend itself vigorously. Based on consideration of all of the facts and circumstances now known, the Company does not believe this claim will have a material impact on its business, financial position, results of operations or cash flows. On March 27, 2011, NASDI received a subpoena from a federal grand jury in the District of Massachusetts directing NASDI to furnish certain documents relating to certain projects performed by NASDI since January 2005. The Company conducted an internal investigation into this matter and continues to fully cooperate with the federal grand jury subpoena. Based on the early stage of the U.S. Department of Justice’s investigation and the limited information known to the Company, the Company cannot predict the outcome of the investigation, the U.S. Attorney’s views of the issues being investigated, any action the U.S. Attorney may take, or the impact, if any, that this matter may have on the Company’s business, financial position, results of operations or cash flows. On March 19, 2013, the Company and three of its current and former executives were sued in a securities class action in the Northern District of Illinois captioned United Union of Roofers, Waterproofers & Allied Workers Local Union No. 8 v. Great Lakes Dredge & Dock Corporation et al., Case No. 1:13-cv-02115. The lawsuit, which was brought on behalf of all purchasers of the Company’s securities between August 7, 2012 and March 14, 2013, primarily alleges that the defendants made false and misleading statements regarding the recognition of revenue in the demolition segment and with regard to the Company’s internal control over financial reporting. This suit was filed following the Company’s announcement on March 14, 2013 that it would restate its second and third quarter 2012 financial statements. Two additional, similar lawsuits captioned Boozer v. Great Lakes Dredge & Dock Corporation et al., Case No. 1:13-cv-02339, and Connors v. Great Lakes Dredge & Dock Corporation et al., Case No. 1:13-cv-02450, were filed in the Northern District of Illinois on March 28, 2013, and April 2, 2013, respectively. The Company denies liability and intends to vigorously defend these actions. On March 28, 2013, the Company was named as a nominal defendant, and its directors were named as defendants, in a shareholder derivative action in DuPage County Circuit Court in Illinois captioned Hammoud v. Berger et al., Case No. 2013CH001110. The lawsuit primarily alleges breaches of fiduciary duties related to allegedly false and misleading statements regarding the recognition of revenue in the demolition segment and with regard to the Company’s internal control over financial reporting, which exposed the Company to securities litigation. A second, similar lawsuit captioned The City of Haverhill Retirement System v. Leight et al., Case No. 1:13-cv-02470, was filed in the Northern District of Illinois on April 2, 2013. The Company has not accrued any amounts with respect to the above matters as the Company does not believe, based on information currently known to it, that a loss relating to these matters is probable, and an estimate of a range of potential losses relating to these matters cannot reasonably be made. During the quarter ended March 31, 2012, a favorable judgment was rendered in the Company’s loss of use claim related to the dredge New York allision in the approach channel to Port Newark, New Jersey. In January 2008, the Company filed suit against the M/V Orange Sun and her owners for damages incurred by the Company in connection with the allision. Following a bench trial in the United States District Court in the Southern District of New York, the Court issued an opinion and order in the Company’s favor, entitling Great Lakes to $11,736 in damages plus pre-judgment interest. Judgment was rendered in the aggregate amount of $13,272. Defendants timely appealed the judgment to the United States Court of Appeals for the Second Circuit. Oral argument was conducted on April 5, 2013 and on April 30, 2013 the appellate panel summarily affirmed the trial court’s opinion in favor of Great Lakes. The defendants are entitled to appeal the decision to either the Second Circuit en banc or the Supreme Court of the United States. The Company cannot be assured whether defendants will continue to appeal the judgment or predict the outcome of any further appellate process.

- Definition

The entire disclosure for commitments and contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6449706&loc=d3e16207-108621

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6398077&loc=d3e12565-110249

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25287-109308

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 14
-Paragraph 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9, 10, 11, 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Nature Of Business And Summary Of Significant Accounting Policies (Effects of Restatement of Certain Line items) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2011	Dec. 31, 2012
CURRENT ASSETS:
Accounts receivable-net	$ 141,250			$ 149,142
Contract revenues in excess of billings	73,916			69,574
Total current assets	288,917			313,690
PROPERTY AND EQUIPMENT-Net	347,740			346,540
Total assets	801,013			826,395
Total Great Lakes Dredge & Dock Corporation equity	274,817			273,635
Contract revenues	188,847	$ 154,907		154,907
Costs of contract revenues	163,064	134,885		134,885
Gross Profit	25,783	20,022		20,022
Operating Income (Loss)	6,594	6,786		6,786
Income tax provision	(104)	564		564
Net income	411	953		953
Net Income (Loss) Attributable to Parent	$ 433	$ 1,068		1,068
Basic earnings per share attributable to Great Lakes Dredge & Dock Corporation	$ 0.01	$ 0.02
Diluted earnings per share attributable to Great Lakes Dredge & Dock Corporation	$ 0.01	$ 0.02
Net Cash Provided by (Used in) Operating Activities	$ (13,232)	$ (18,244)	$ (18,244)
Net Cash Provided by (Used in) Investing Activities	(15,456)	$ (8,033)	(8,033)
Parent Company [Member]
CURRENT ASSETS:
Total current assets	14,647			52,748
Total assets	670,809			677,161
Total Great Lakes Dredge & Dock Corporation equity	274,817			273,635
Operating Income (Loss)				(512)
Income tax provision	3,473			(79)
Net income	411			964
Net Income (Loss) Attributable to Parent	433			$ 1,079
Net Cash Provided by (Used in) Operating Activities	$ (2,952)		$ (13,845)

Nature Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Shares excluded from computation of diluted earnings per share			0	0	0
Net income	$ 411	$ 953				$ 953
Maximum [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Average equipment-related costs of total costs of contract revenue	23.00%
Minimum [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Average equipment-related costs of total costs of contract revenue	20.00%

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 13, 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

+ Details

Accounts Receivable And Contracts In Progress (Tables)

3 Months Ended

Mar. 31, 2013

Accounts Receivable And Contracts In Progress [Abstract]

Schedule Of Accounts Receivable


	March 31,		December 31,
	2013		2012
Completed contracts	$	56,984	$	43,898
Contracts in progress		74,653		91,459
Retainage		20,119		24,419
		151,756		159,776
Allowance for doubtful accounts		(2,469)		(2,050)

Total accounts receivable—net	$	149,287	$	157,726

Current portion of accounts receivable—net	$	141,250	$	149,142
Long-term accounts receivable and retainage		8,037		8,584
Total accounts receivable—net	$	149,287	$	157,726

Components Of Contracts In Progress


	March 31,		December 31,
	2013		2012
Costs and earnings in excess of billings:
Costs and earnings for contracts in progress	$	346,231	$	458,750
Amounts billed		(279,717)		(392,860)
Costs and earnings in excess of billings for contracts in progress		66,514		65,890

Costs and earnings in excess of billings for completed contracts		7,402		3,684

Total contract revenues in excess of billings	$	73,916	$	69,574

Billings in excess of costs and earnings:
Amounts billed	$	(376,801)	$	(338,741)
Costs and earnings for contracts in progress		367,272		327,461

Total billings in excess of contract revenues	$	(9,529)	$	(11,280)

Fair Value Measurements

3 Months Ended

Mar. 31, 2013

Fair Value Measurements [Abstract]

Fair Value Measurements

4. Fair value measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. A fair value hierarchy has been established by GAAP that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The accounting guidance describes three levels of inputs that may be used to measure fair value:

Level 1—Quoted prices in active markets for identical assets or liabilities.

Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The Company utilizes the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. At March 31, 2013 and December 31, 2012, the Company held certain derivative contracts that it uses to manage commodity price risk. The Company does not hold or issue derivatives for speculative or trading purposes. The fair values of these financial instruments are summarized as follows:


				Fair Value Measurements at Reporting Date Using
Description	At March 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)

Fuel hedge contracts	$	150	$	-	$	150	$	-

				Fair Value Measurements at Reporting Date Using
Description	At December 31, 2012		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)

Fuel hedge contracts	$	178	$	-	$	178	$	-

Fuel hedge contracts

The Company is exposed to certain market risks, primarily commodity price risk as it relates to the diesel fuel purchase requirements, which occur in the normal course of business. The Company enters into heating oil commodity swap contracts to hedge the risk that fluctuations in diesel fuel prices will have an adverse impact on cash flows associated with its domestic dredging contracts. The Company’s goal is to hedge approximately 80% of the fuel requirements for work in backlog.

As of March 31, 2013, the Company was party to various swap arrangements to hedge the price of a portion of its diesel fuel purchase requirements for work in its backlog to be performed through March 2014. As of March 31, 2013, there were 2.0 million gallons remaining on these contracts which represent approximately 80% of the Company’s forecasted fuel purchases through March 2014. Under these swap agreements, the Company will pay fixed prices ranging from $3.01 to $3.26 per gallon.

At March 31, 2013, the fair value liability of the fuel hedge contracts was estimated to be $150 and is recorded in accrued expenses. At December 31, 2012 the fair value asset of the fuel hedge contracts was estimated to be $178 and is recorded in accrued expenses. The loss reclassified to earnings from changes in fair value of derivatives, net of cash settlements and taxes, for the three months ended March 31, 2013 was $137. The remaining gains and losses included in accumulated other comprehensive income (loss) at March 31, 2013 will be reclassified into earnings over the next twelve months, corresponding to the period during which the hedged fuel is expected to be utilized. The fair values of fuel hedges are corroborated using inputs that are readily observable in public markets; therefore, the Company determines fair value of these fuel hedges using Level 2 inputs.

The fair value of the fuel hedge contracts outstanding as of March 31, 2013 and December 31, 2012 is as follows:


		Fair Value at
		March 31,		December 31,
	Balance Sheet Location	2013		2012

Liability derivatives:
Derivatives designated as hedges
Fuel hedge contracts	Accrued expenses	$	150	$	178

Accumulated other comprehensive income

Changes in the components of the accumulated balances of other comprehensive income are as follows:


	Three months ended, March 31,
	2013		2012
Cumulative translation adjustments—net of tax	$	(6)	$	4
Derivatives:
Reclassification of derivative losses (gains) to earnings—net of tax		137		(406)
Change in fair value of derivatives—net of tax		(120)		880
Net unrealized gain on derivatives—net of tax		17		474
Total other comprehensive income	$	11	$	478

Adjustments reclassified from accumulated balances of other comprehensive income to earnings are as follows:


		Three months ended March 31,
	Statement of Operations Location	2013		2012
Derivatives:
Fuel hedge contracts	Costs of contract revenues	$	228	$	(675)
	Income tax (provision) benefit		(91)		269
		$	137	$	(406)

Other financial instruments

The carrying value of financial instruments included in current assets and current liabilities approximates fair value due to the short-term maturities of these instruments. In January 2011, the Company issued $250,000 of 7.375% senior notes due February 1, 2019, which were outstanding at March 31, 2013. The senior notes are senior unsecured obligations of the Company and its subsidiaries that guarantee the senior notes. The fair value of the senior notes was $263,750 at March 31, 2013, which is a Level 1 fair value measurement as the senior notes value was obtained using quoted prices in active markets.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13537-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13504-108611

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15B
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44A, 44B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 17-22, 27, 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15A
-Subparagraph a-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15C, 15D
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32, 33, 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 3, 10, 14, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Segment Information (Tables)

3 Months Ended

Mar. 31, 2013

Segment Information [Abstract]

Segment Reporting By Segment


	Three Months Ended
	March 31,
	2013		2012
Dredging
Contract revenues	$	173,959	$	123,673
Operating income		19,000		4,899

Demolition
Contract revenues	$	14,888	$	32,546
Operating income (loss)		(12,406)		1,887

Intersegment revenues	$	-	$	(1,312)
Total
Contract revenues	$	188,847	$	154,907
Operating income		6,594		6,786

- Definition

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References + Details

Segment Information

3 Months Ended

Mar. 31, 2013

Segment Information [Abstract]

Segment Information

7. Segment information

The Company and its subsidiaries currently operate in two reportable segments: dredging and demolition. The Company’s financial reporting systems present various data for management to run the business, including profit and loss statements prepared according to the segments presented. Management uses operating income to evaluate performance between the two segments. Segment information for the periods presented is provided as follows:


	Three Months Ended
	March 31,
	2013		2012
Dredging
Contract revenues	$	173,959	$	123,673
Operating income		19,000		4,899

Demolition
Contract revenues	$	14,888	$	32,546
Operating income (loss)		(12,406)		1,887

Intersegment revenues	$	-	$	(1,312)
Total
Contract revenues	$	188,847	$	154,907
Operating income		6,594		6,786

Foreign dredging revenue of $38,385 and $18,025 for the three months ended March 31, 2013 and 2012, respectively, was primarily attributable to work done in the Middle East as well as for the Wheatstone LNG project in Western Australia.

The majority of the Company’s long-lived assets are marine vessels and related equipment. At any point in time, the Company may employ certain assets outside of the U.S., as needed, to perform work on the Company’s foreign projects.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8906-108599

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Subsidiary Guarantors (Condensed Consolidated Statement Operations And Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Contract revenues	$ 188,847	$ 154,907	$ 154,907
Costs of contract revenues	(163,064)	(134,885)	(134,885)
GROSS PROFIT	25,783	20,022	20,022
General and administrative expenses	19,187	13,267	13,267
Gain on sale of assets-net	2	(31)	(31)
Total operating income	6,594	6,786	6,786
Interest expense-net	(5,733)	(5,259)	(5,259)
Equity in earnings (loss) of joint ventures	(590)	(16)	(16)
Loss on foreign currency transactions-net	36	6	6
INCOME BEFORE INCOME TAXES	307	1,517	1,517
Income tax (provision) benefit	104	(564)	(564)
NET INCOME	411	953	953
Net (income) loss attributable to noncontrolling interests	22	115	115
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OF GREAT LAKES DREDGE & DOCK CORPORATION	433	$ 1,068	1,068
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	444		1,546
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
General and administrative expenses			512
Gain on sale of assets-net			11
Total operating income			(512)
Interest expense-net	(5,672)		(4,950)
Equity in earnings (loss) of subsidiaries	9,556		6,347
INCOME BEFORE INCOME TAXES	3,884		885
Income tax (provision) benefit	(3,473)		79
NET INCOME	411		964
Net (income) loss attributable to noncontrolling interests	22		115
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OF GREAT LAKES DREDGE & DOCK CORPORATION	433		1,079
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	444		1,546
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Contract revenues	185,419		155,444
Costs of contract revenues	(159,932)		(135,167)
GROSS PROFIT	25,487		20,277
General and administrative expenses	18,996		12,569
Gain on sale of assets-net	2		(42)
Total operating income	6,489		7,750
Interest expense-net	(19)		(281)
Equity in earnings (loss) of subsidiaries	(47)		(379)
Equity in earnings (loss) of joint ventures	(590)		(16)
Loss on foreign currency transactions-net	36		6
INCOME BEFORE INCOME TAXES	5,869		7,080
Income tax (provision) benefit	3,577		(643)
NET INCOME	9,446		6,437
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OF GREAT LAKES DREDGE & DOCK CORPORATION	9,446		6,437
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	9,463		6,911
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Contract revenues	3,759		1,799
Costs of contract revenues	(3,463)		(2,054)
GROSS PROFIT	296		(255)
General and administrative expenses	191		186
Total operating income	105		(441)
Interest expense-net	(42)		(28)
INCOME BEFORE INCOME TAXES	63		(469)
NET INCOME	63		(469)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OF GREAT LAKES DREDGE & DOCK CORPORATION	63		(469)
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	57		(465)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Contract revenues	(331)		(2,336)
Costs of contract revenues	331		2,336
Equity in earnings (loss) of subsidiaries	(9,509)		(5,968)
INCOME BEFORE INCOME TAXES	(9,509)		(5,968)
NET INCOME	(9,509)		(5,968)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OF GREAT LAKES DREDGE & DOCK CORPORATION	(9,509)		(5,968)
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	$ (9,520)		$ (6,446)

Long-term Debt (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended
	Jun. 04, 2012	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Jan. 31, 2011
Debt Instrument [Line Items]
Revolving credit facility, interest rate description	Depending on the Company's consolidated leverage ratio (as defined in the Credit Agreement), borrowings under the new revolving credit facility will bear interest at the option of the Company at either a LIBOR rate plus a margin of between 1.50% to 2.50% per annum or a base rate plus a margin of between 0.50% to 1.50% per annum.
Line of Credit Facility, Amount Outstanding		$ 21,500
Letters of credit outstanding		33,420
Letter of credit remaining borrowing capacity		120,080
Senior Notes		$ 250,000		$ 250,000	$ 250,000
Senior notes percentage		7.375%
Amortization of deferred financing fees		$ 288	$ 334
Internaional Line Of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		24,000
Parent Company [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding		21,500
Senior Notes		250,000		$ 250,000
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 125,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	175,000
Line of credit facility optional increase capacity	50,000
Line of Credit Facility, Amount Outstanding		$ 21,500
Multicurrency [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	50,000
Swingline Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 10,000
Maximum [Member] \| LIBOR Rate [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility, basis spread on variable rate	2.50%
Maximum [Member] \| Base Rate [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility, basis spread on variable rate	1.50%

Document And Entity Information - shares	3 Months Ended
Document And Entity Information - shares	Mar. 31, 2013	May 03, 2013
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Trading Symbol	GLDD
Entity Registrant Name	Great Lakes Dredge & Dock CORP
Entity Central Index Key	0001372020
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		59,390,161
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes

Fair Value Measurements (Accumulated Other Comprehensive adjustments) (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2013

Mar. 31, 2012

Fair Value Measurements [Abstract]

Cumulative translation adjustments-net of tax

$ (6)

$ 4

Reclassification of derivative losses (gains) to earnings-net of tax

137

(406)

Net unrealized gain on derivatives-net of tax

(120)

880

Net unrealized gain on derivatives-net of tax

^[1]

474

Other comprehensive loss-net of tax

$ 11

$ 478

[1]	Net of income tax benefit of $11 and $315 for the three months ended March 31, 2013 and 2012, respectively.

- Definition

+ References

+ Details

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2013

Accrued Expenses [Abstract]

Accrued Expenses


	March 31,		December 31,
	2013		2012

Insurance	$	10,139	$	9,070
Payroll and employee benefits		9,560		9,906
Construction liabilities		9,423		6,426
Interest		3,401		7,837
Income and other taxes		1,903		1,699
Plant & overhead accrual		1,898		-
Percentage of completion adjustment		1,719		1,552
Other		2,518		2,000
Total accrued expenses	$	40,561	$	38,490

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	59,274,393	58,999,404
Common stock, shares outstanding	59,274,393	58,999,404

Consolidated Statements Of Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss)[Member]	Noncontrolling Interests [Member]	Total
BALANCE - value at Dec. 31, 2011	$ 6	$ 267,918	$ 24,042	$ 3	$ 568	$ 292,537
BALANCE - shares at Dec. 31, 2011	58,999
Share-based compensation, Value		1,015				1,015
Share-based compensation, Shares	94
Vesting of restricted stock units, including impact of shares withheld for taxes, value		(2)				(2)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares	9
Exercise of stock options, Value		40				40
Exercise of stock options, Shares	8
Excess income tax benefit from share based compensation		27				27
Dividends declared and paid			(1,240)			(1,240)
Dividend equivalents paid on restricted stock units			(12)			(12)
Net income			1,068		(115)	953
Other comprehensive loss-net of tax				478		478
BALANCE - value at Mar. 31, 2012	$ 6	268,998	23,858	481	453	293,796
BALANCE - shares at Mar. 31, 2012	59,111
BALANCE - value at Dec. 31, 2011	$ 6	267,918	24,042	3	568	292,537
BALANCE - shares at Dec. 31, 2011	58,999
Net income						953
BALANCE - value at Dec. 31, 2012	$ 6	271,418	2,591	(380)	(210)	273,425
BALANCE - shares at Dec. 31, 2012	59,359
Share-based compensation, Value		751				751
Share-based compensation, Shares	27
Vesting of restricted stock units, including impact of shares withheld for taxes, value		(28)				(28)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares	5
Excess income tax benefit from share based compensation		15				15
Net income			433		(22)	411
Other comprehensive loss-net of tax				11		11
BALANCE - value at Mar. 31, 2013	$ 6	$ 272,156	$ 3,024	$ (369)	$ (232)	$ 274,585
BALANCE - shares at Mar. 31, 2013	59,391

Subsidiary Guarantors (Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jan. 31, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 6,643	$ 24,440	$ 85,618	$ 24,440	$ 85,618		$ 113,288
Accounts receivable-net	141,250	149,142
Contract revenues in excess of billings	73,916	69,574
Inventories	26,629	28,726
Prepaid Expense and Other Assets, Current	40,479	41,808
Total current assets	288,917	313,690
PROPERTY AND EQUIPMENT-Net	347,740	346,540
GOODWILL AND OTHER INTANGIBLE	103,967	104,031
INVENTORIES-Noncurrent	36,423	37,392
INVESTMENTS IN JOINT VENTURES	6,457	7,047
OTHER	17,509	17,695
TOTAL	801,013	826,395
LIABILITIES AND EQUITY
Accounts payable	88,624	123,082
Accrued expenses	40,561	38,490
Billings in excess of contract revenues	9,529	11,280
Current portion of long term debt	2,526	13,098
Total current liabilities	141,240	185,950
7 3/8% SENIOR NOTES	250,000	250,000				$ 250,000
Line of Credit Facility, Amount Outstanding	21,500
DEFERRED INCOME TAXES	103,436	106,767
OTHER	10,252	10,253
Total liabilities	526,428	552,970
EQUITY:
Total Great Lakes Dredge & Dock Corporation equity	274,817	273,635
NONCONTROLLING INTERESTS	(232)	(210)
Total equity	274,585	273,425	$ 293,796	292,537
TOTAL	801,013	826,395
Parent Company [Member]
ASSETS
Receivables from affiliates	3,514	38,115
Prepaid Expense and Other Assets, Current	11,133	14,633
Total current assets	14,647	52,748
INVESTMENTS IN SUBSIDIARIES	650,100	618,070
OTHER	6,062	6,343
TOTAL	670,809	677,161
LIABILITIES AND EQUITY
Accounts payable	405
Payables to affiliates	16,525	38,647
Accrued expenses	3,855	8,396
Total current liabilities	20,785	47,043
7 3/8% SENIOR NOTES	250,000	250,000
Line of Credit Facility, Amount Outstanding	21,500
DEFERRED INCOME TAXES	103,391	106,144
OTHER	548	549
Total liabilities	396,224	403,736
EQUITY:
Total Great Lakes Dredge & Dock Corporation equity	274,817	273,635
NONCONTROLLING INTERESTS	(232)	(210)
Total equity	274,585	273,425
TOTAL	670,809	677,161
Subsidiary Guarantors [Member]
ASSETS
Cash and cash equivalents	6,336	24,272		24,272	85,425		108,985
Accounts receivable-net	137,857	147,610
Receivables from affiliates	87,422	102,968
Contract revenues in excess of billings	73,450	69,649
Inventories	26,629	28,726
Prepaid Expense and Other Assets, Current	29,326	27,147
Total current assets	361,020	400,372
PROPERTY AND EQUIPMENT-Net	347,706	346,503
GOODWILL AND OTHER INTANGIBLE	103,633	103,687
INVENTORIES-Noncurrent	36,423	37,392
INVESTMENTS IN JOINT VENTURES	6,457	7,047
INVESTMENTS IN SUBSIDIARIES	2,081	2,127
OTHER	11,444	11,350
TOTAL	868,764	908,478
LIABILITIES AND EQUITY
Accounts payable	86,909	122,191
Payables to affiliates	75,529	105,303
Accrued expenses	35,980	29,417
Billings in excess of contract revenues	9,474	11,207
Current portion of long term debt	2,526	13,098
Total current liabilities	210,418	281,216
DEFERRED INCOME TAXES	45	623
OTHER	9,704	9,704
Total liabilities	220,167	291,543
EQUITY:
Total Great Lakes Dredge & Dock Corporation equity	648,597	616,935
Total equity	648,597	616,935
TOTAL	868,764	908,478
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	307	168		$ 168	$ 193		$ 4,303
Accounts receivable-net	3,393	1,532
Receivables from affiliates	5,982	7,680
Contract revenues in excess of billings	534	5
Prepaid Expense and Other Assets, Current	20	28
Total current assets	10,236	9,413
PROPERTY AND EQUIPMENT-Net	34	37
GOODWILL AND OTHER INTANGIBLE	334	344
OTHER	3	2
TOTAL	10,607	9,796
LIABILITIES AND EQUITY
Accounts payable	1,310	891
Payables to affiliates	4,720	4,843
Accrued expenses	726	677
Billings in excess of contract revenues	267	123
Total current liabilities	7,023	6,534
Total liabilities	7,023	6,534
EQUITY:
Total Great Lakes Dredge & Dock Corporation equity	3,584	3,262
Total equity	3,584	3,262
TOTAL	10,607	9,796
Eliminations [Member]
ASSETS
Receivables from affiliates	(96,918)	(148,763)
Contract revenues in excess of billings	(68)	(80)
Total current assets	(96,986)	(148,843)
INVESTMENTS IN SUBSIDIARIES	(652,181)	(620,197)
TOTAL	(749,167)	(769,040)
LIABILITIES AND EQUITY
Payables to affiliates	(96,774)	(148,793)
Billings in excess of contract revenues	(212)	(50)
Total current liabilities	(96,986)	(148,843)
Total liabilities	(96,986)	(148,843)
EQUITY:
Total Great Lakes Dredge & Dock Corporation equity	(652,181)	(620,197)
Total equity	(652,181)	(620,197)
TOTAL	$ (749,167)	$ (769,040)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			0	0	0
Net income (loss) attributable to common shareholders of Great Lakes Dredge & Dock Corporation	$ 433	$ 1,068				$ 1,068
Weighted-average common shares outstanding - basic	59,369	59,038
Effect of stock options and restricted stock units	648	396
Weighted-average common shares outstanding - diluted	60,017	59,434
Earnings per share - basic	$ 0.01	$ 0.02
Earnings per share - diluted	$ 0.01	$ 0.02
Parent Company [Member]
Net income (loss) attributable to common shareholders of Great Lakes Dredge & Dock Corporation	$ 433					$ 1,079

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.21)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=16381557&loc=d3e4984-109258

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.23)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 18
-Article 7

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 36, 37, 38
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 20
-Article 5

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 21
-Article 9

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References + Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 10, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph A7
-Appendix A

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 87-21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28, 29, 30
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References + Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Weighted-Average Number of Common Shares Outstanding
-URI http://asc.fasb.org/extlink&oid=6528421

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012
Accrued Expenses [Abstract]
Insurance	$ 10,139	$ 9,070
Payroll and employee benefits	9,560	9,906
Construction liabilities	9,423	6,426
Interest	3,401	7,837
Income and other taxes	1,903	1,699
Plant & overhead accrual	1,898
Percentage of completion adjustment	1,719	1,552
Other	2,518	2,000
Total accrued expenses	$ 40,561	$ 38,490

Nature Of Business And Summary Of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2013

Nature Of Business And Summary Of Significant Accounting Policies [Abstract]

Computations For Basic And Diluted Earnings Per Share


	Three Months Ended
	March 31,
	2013		2012
Net income attributable to common shareholders of Great Lakes Dredge & Dock Corporation	$	433	$	1,068

Weighted-average common shares outstanding — basic		59,369		59,038
Effect of stock options and restricted stock units		648		396

Weighted-average common shares outstanding — diluted		60,017		59,434

Earnings per share — basic	$	0.01	$	0.02
Earnings per share — diluted	$	0.01	$	0.02

Accounts Receivable And Contracts In Progress (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012
Accounts Receivable [Line Items]
Retainage	$ 20,119	$ 24,419
Accounts Receivable, Gross	151,756	159,776
Allowance for doubtful accounts	(2,469)	(2,050)
Total accounts receivable-net	149,287	157,726
Current portion of accounts receivable-net	141,250	149,142
Long-term accounts receivable and retainage	8,037	8,584
Completed Contracts [Member]
Accounts Receivable [Line Items]
Contracts	56,984	43,898
Contracts In Progress [Member]
Accounts Receivable [Line Items]
Contracts	$ 74,653	$ 91,459

Subsidiary Guarantors

3 Months Ended

Mar. 31, 2013

Subsidiary Guarantors [Abstract]

Subsidiary Guarantors

9. Subsidiary guarantors

The Company’s long-term debt at March 31, 2013 includes $250,000 of 7.375% senior notes due February 1, 2019. The Company’s obligations under these senior unsecured notes are guaranteed by the Company’s 100% owned domestic subsidiaries. Such guarantees are full, unconditional and joint and several.

The following supplemental financial information sets forth for the Company’s subsidiary guarantors (on a combined basis), the Company’s non-guarantor subsidiaries (on a combined basis) and Great Lakes Dredge & Dock Corporation, exclusive of its subsidiaries (“GLDD Corporation”):


	(i)	balance sheets as of March 31, 2013 and December 31, 2012;


	(ii)	statements of operations and comprehensive income for the three months ended March 31, 2013 and 2012; and

(iii)

statements of cash flows for the three months ended March 31, 2013 and 2012.


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING BALANCE SHEET
AS OF MARCH 31, 2013
(In thousands)

ASSETS	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals
CURRENT ASSETS:
Cash and cash equivalents	$	6,336	$	307	$	-	$	-	$	6,643
Accounts receivable — net		137,857		3,393		-		-		141,250
Receivables from affiliates		87,422		5,982		3,514		(96,918)		-
Contract revenues in excess of billings		73,450		534		-		(68)		73,916
Inventories		26,629		-		-		-		26,629
Prepaid expenses and other current assets		29,326		20		11,133		-		40,479
Total current assets		361,020		10,236		14,647		(96,986)		288,917

PROPERTY AND EQUIPMENT—Net		347,706		34		-		-		347,740
GOODWILL AND OTHER INTANGIBLE ASSETS—Net		103,633		334		-		-		103,967
INVENTORIES — Noncurrent		36,423		-		-		-		36,423
INVESTMENTS IN JOINT VENTURES		6,457		-		-		-		6,457
INVESTMENTS IN SUBSIDIARIES		2,081		-		650,100		(652,181)		-
OTHER		11,444		3		6,062		-		17,509
TOTAL	$	868,764	$	10,607	$	670,809	$	(749,167)	$	801,013

LIABILITIES AND EQUITY
CURRENT LIABILITIES:
Accounts payable	$	86,909	$	1,310	$	405	$	-	$	88,624
Payables to affiliates		75,529		4,720		16,525		(96,774)		-
Accrued expenses		35,980		726		3,855		-		40,561
Billings in excess of contract revenues		9,474		267		-		(212)		9,529
Current portion of long term debt		2,526		-		-		-		2,526
Total current liabilities		210,418		7,023		20,785		(96,986)		141,240

7 3/8% SENIOR NOTES		-		-		250,000		-		250,000
REVOLVING CREDIT FACILITY		-		-		21,500		-		21,500
DEFERRED INCOME TAXES		45		-		103,391		-		103,436
OTHER		9,704		-		548		-		10,252
Total liabilities		220,167		7,023		396,224		(96,986)		526,428

Total Great Lakes Dredge & Dock Corporation Equity		648,597		3,584		274,817		(652,181)		274,817
NONCONTROLLING INTERESTS		-		-		(232)		-		(232)
TOTAL EQUITY		648,597		3,584		274,585		(652,181)		274,585
TOTAL	$	868,764	$	10,607	$	670,809	$	(749,167)	$	801,013


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING BALANCE SHEET
AS OF DECEMBER 31, 2012
(In thousands)

ASSETS	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals
CURRENT ASSETS:
Cash and cash equivalents	$	24,272	$	168	$	-	$	-	$	24,440
Accounts receivable — net		147,610		1,532		-		-		149,142
Receivables from affiliates		102,968		7,680		38,115		(148,763)		-
Contract revenues in excess of billings		69,649		5		-		(80)		69,574
Inventories		28,726		-		-		-		28,726
Prepaid expenses and other current assets		27,147		28		14,633		-		41,808
Total current assets		400,372		9,413		52,748		(148,843)		313,690

PROPERTY AND EQUIPMENT—Net		346,503		37		-		-		346,540
GOODWILL AND OTHER INTANGIBLE ASSETS—Net		103,687		344		-		-		104,031
INVENTORIES — Noncurrent		37,392		-		-		-		37,392
INVESTMENTS IN JOINT VENTURES		7,047		-		-		-		7,047
INVESTMENTS IN SUBSIDIARIES		2,127		-		618,070		(620,197)		-
OTHER		11,350		2		6,343		-		17,695
TOTAL	$	908,478	$	9,796	$	677,161	$	(769,040)	$	826,395

LIABILITIES AND EQUITY
CURRENT LIABILITIES:
Accounts payable	$	122,191	$	891	$	-	$	-	$	123,082
Payables to affiliates		105,303		4,843		38,647		(148,793)		-
Accrued expenses		29,417		677		8,396		-		38,490
Billings in excess of contract revenues		11,207		123		-		(50)		11,280
Current portion of long term debt		13,098		-		-		-		13,098
Total current liabilities		281,216		6,534		47,043		(148,843)		185,950

7 3/4% SENIOR SUBORDINATED NOTES		-		-		250,000		-		250,000
DEFERRED INCOME TAXES		623		-		106,144		-		106,767
OTHER		9,704		-		549		-		10,253
Total liabilities		291,543		6,534		403,736		(148,843)		552,970

Total Great Lakes Dredge & Dock Corporation Equity		616,935		3,262		273,635		(620,197)		273,635
NONCONTROLLING INTERESTS		-		-		(210)		-		(210)
TOTAL EQUITY		616,935		3,262		273,425		(620,197)		273,425
TOTAL	$	908,478	$	9,796	$	677,161	$	(769,040)	$	826,395


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
FOR THE THREE MONTHS ENDED MARCH 31, 2013
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

Contract revenues	$	185,419	$	3,759	$	-	$	(331)	$	188,847
Costs of contract revenues		(159,932)		(3,463)		-		331		(163,064)
Gross profit		25,487		296		-		-		25,783

OPERATING EXPENSES:
General and administrative expenses		18,996		191		-		-		19,187
(Gain) loss on sale of assets—net		2		-		-		-		2
Operating income (loss)		6,489		105		-		-		6,594

Interest expense—net		(19)		(42)		(5,672)		-		(5,733)
Equity in earnings (loss) of subsidiaries		(47)		-		9,556		(9,509)		-
Equity in earnings of joint ventures		(590)		-		-		-		(590)
Gain on foreign currency transactions—net		36		-		-		-		36

Income (loss) before income taxes		5,869		63		3,884		(9,509)		307

Income tax (provision) benefit		3,577		-		(3,473)		-		104

Net income (loss)		9,446		63		411		(9,509)		411
Net loss attributable to noncontrolling interests		-		-		22		-		22
Net income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	9,446	$	63	$	433	$	(9,509)	$	433


Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	9,463	$	57	$	444	$	(9,520)	$	444


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
FOR THE THREE MONTHS ENDED MARCH 31, 2012
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

Contract revenues	$	155,444	$	1,799	$	-	$	(2,336)	$	154,907
Costs of contract revenues		(135,167)		(2,054)		-		2,336		(134,885)
Gross profit		20,277		(255)		-		-		20,022

OPERATING EXPENSES:
General and administrative expenses		12,569		186		512		-		13,267
(Gain) loss on sale of assets—net		(42)		-		11		-		(31)
Operating income (loss)		7,750		(441)		(512)		-		6,786

Interest expense—net		(281)		(28)		(4,950)		-		(5,259)
Equity in earnings (loss) of subsidiaries		(379)		-		6,347		(5,968)		-
Equity in earnings of joint ventures		(16)		-		-		-		(16)
Loss on foreign currency transactions, net		6		-		-		-		6

Income (loss) before income taxes		7,080		(469)		885		(5,968)		1,517

Income tax (provision) benefit		(643)		-		79		-		(564)

Net income (loss)		6,437		(469)		964		(5,968)		953
Net income attributable to noncontrolling interests		-		-		115		-		115
Net income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	6,437	$	(469)	$	1,079	$	(5,968)	$	1,068

Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	6,911	$	(465)	$	1,546	$	(6,446)	$	1,546


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE THREE MONTHS ENDED MARCH 31, 2013
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	$	(10,786)	$	506	$	(2,952)	$	-	$	(13,232)

INVESTING ACTIVITIES:
Purchases of property and equipment		(15,514)		-		-		-		(15,514)
Proceeds from dispositions of property and equipment		58		-		-		-		58

Net cash flows used in investing activities		(15,456)		-		-		-		(15,456)

FINANCING ACTIVITIES:
Repayments of long term note payable		-		-		(10,547)		-		(10,547)
Taxes paid on settlement of vested share awards		-		-		(28)		-		(28)
Net change in accounts with affiliates		8,331		(343)		(7,988)		-		-
Repayments of equipment debt		(25)		-		-		-		(25)
Excess income tax benefit from share-based compensation		-		-		15		-		15
Borrowings under revolving loans		-		-		79,500		-		79,500
Repayments of revolving loans		-		-		(58,000)		-		(58,000)

Net cash flows provided by (used in) financing activities		8,306		(343)		2,952		-		10,915

Effect of foreign currency exchange rates on cash and cash equivalents		-		(24)		-		-		(24)

Net decrease in cash and cash equivalents		(17,936)		139		-		-		(17,797)

Cash and cash equivalents at beginning of period		24,272		168		-		-		24,440

Cash and cash equivalents at end of period	$	6,336	$	307	$	-	$	-	$	6,643


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE THREE MONTHS ENDED MARCH 31, 2012
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	$	(5,200)	$	801	$	(13,845)	$	-	$	(18,244)

INVESTING ACTIVITIES:
Purchases of property and equipment		(8,101)		-		-		-		(8,101)
Proceeds from dispositions of property and equipment		68		-		-		-		68

Net cash flows used in investing activities		(8,033)		-		-		-		(8,033)

FINANCING ACTIVITIES:
Dividends paid		-		-		(1,240)		-		(1,240)
Dividend equivalents paid on restricted stock units		-		-		(12)		-		(12)
Taxes paid on vested share awards		-		-		(2)				(2)
Net change in accounts with affiliates		(10,089)		(4,978)		15,067		-		-
Capital contributions		-		35		(35)		-		-
Repayments of equipment debt		(238)		-		-		-		(238)
Exercise of stock options		-		-		40		-		40
Excess income tax benefit from share-based compensation		-		-		27		-		27

Net cash flows provided by financing activities		(10,327)		(4,943)		13,845		-		(1,425)

Effect of foreign currency exchange rates on cash and cash equivalents		-		32		-		-		32

Net increase in cash and cash equivalents		(23,560)		(4,110)		-		-		(27,670)

Cash and cash equivalents at beginning of period		108,985		4,303		-		-		113,288

Cash and cash equivalents at end of period	$	85,425	$	193	$	-	$	-	$	85,618

- Definition

The entire disclosure for condensed financial information, including the financial position, cash flows, and the results of operations of the registrant (parent company) as of the same dates or for the same periods for which audited consolidated financial statements are being presented. Alternatively, the details of this disclosure can be reported by the specific parent company taxonomy elements, indicating the appropriate date and period contexts in an instance document.

+ References + Details

Subsidiary Guarantors (Tables)

3 Months Ended

9 Months Ended

12 Months Ended

Mar. 31, 2013

Sep. 30, 2011

Dec. 31, 2012

Subsidiary Guarantors [Abstract]

Condensed Consolidating of Balance Sheet


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING BALANCE SHEET
AS OF MARCH 31, 2013
(In thousands)

ASSETS	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals
CURRENT ASSETS:
Cash and cash equivalents	$	6,336	$	307	$	-	$	-	$	6,643
Accounts receivable — net		137,857		3,393		-		-		141,250
Receivables from affiliates		87,422		5,982		3,514		(96,918)		-
Contract revenues in excess of billings		73,450		534		-		(68)		73,916
Inventories		26,629		-		-		-		26,629
Prepaid expenses and other current assets		29,326		20		11,133		-		40,479
Total current assets		361,020		10,236		14,647		(96,986)		288,917

PROPERTY AND EQUIPMENT—Net		347,706		34		-		-		347,740
GOODWILL AND OTHER INTANGIBLE ASSETS—Net		103,633		334		-		-		103,967
INVENTORIES — Noncurrent		36,423		-		-		-		36,423
INVESTMENTS IN JOINT VENTURES		6,457		-		-		-		6,457
INVESTMENTS IN SUBSIDIARIES		2,081		-		650,100		(652,181)		-
OTHER		11,444		3		6,062		-		17,509
TOTAL	$	868,764	$	10,607	$	670,809	$	(749,167)	$	801,013

LIABILITIES AND EQUITY
CURRENT LIABILITIES:
Accounts payable	$	86,909	$	1,310	$	405	$	-	$	88,624
Payables to affiliates		75,529		4,720		16,525		(96,774)		-
Accrued expenses		35,980		726		3,855		-		40,561
Billings in excess of contract revenues		9,474		267		-		(212)		9,529
Current portion of long term debt		2,526		-		-		-		2,526
Total current liabilities		210,418		7,023		20,785		(96,986)		141,240

7 3/8% SENIOR NOTES		-		-		250,000		-		250,000
REVOLVING CREDIT FACILITY		-		-		21,500		-		21,500
DEFERRED INCOME TAXES		45		-		103,391		-		103,436
OTHER		9,704		-		548		-		10,252
Total liabilities		220,167		7,023		396,224		(96,986)		526,428

Total Great Lakes Dredge & Dock Corporation Equity		648,597		3,584		274,817		(652,181)		274,817
NONCONTROLLING INTERESTS		-		-		(232)		-		(232)
TOTAL EQUITY		648,597		3,584		274,585		(652,181)		274,585
TOTAL	$	868,764	$	10,607	$	670,809	$	(749,167)	$	801,013


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING BALANCE SHEET
AS OF DECEMBER 31, 2012
(In thousands)

ASSETS	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals
CURRENT ASSETS:
Cash and cash equivalents	$	24,272	$	168	$	-	$	-	$	24,440
Accounts receivable — net		147,610		1,532		-		-		149,142
Receivables from affiliates		102,968		7,680		38,115		(148,763)		-
Contract revenues in excess of billings		69,649		5		-		(80)		69,574
Inventories		28,726		-		-		-		28,726
Prepaid expenses and other current assets		27,147		28		14,633		-		41,808
Total current assets		400,372		9,413		52,748		(148,843)		313,690

PROPERTY AND EQUIPMENT—Net		346,503		37		-		-		346,540
GOODWILL AND OTHER INTANGIBLE ASSETS—Net		103,687		344		-		-		104,031
INVENTORIES — Noncurrent		37,392		-		-		-		37,392
INVESTMENTS IN JOINT VENTURES		7,047		-		-		-		7,047
INVESTMENTS IN SUBSIDIARIES		2,127		-		618,070		(620,197)		-
OTHER		11,350		2		6,343		-		17,695
TOTAL	$	908,478	$	9,796	$	677,161	$	(769,040)	$	826,395

LIABILITIES AND EQUITY
CURRENT LIABILITIES:
Accounts payable	$	122,191	$	891	$	-	$	-	$	123,082
Payables to affiliates		105,303		4,843		38,647		(148,793)		-
Accrued expenses		29,417		677		8,396		-		38,490
Billings in excess of contract revenues		11,207		123		-		(50)		11,280
Current portion of long term debt		13,098		-		-		-		13,098
Total current liabilities		281,216		6,534		47,043		(148,843)		185,950

7 3/4% SENIOR SUBORDINATED NOTES		-		-		250,000		-		250,000
DEFERRED INCOME TAXES		623		-		106,144		-		106,767
OTHER		9,704		-		549		-		10,253
Total liabilities		291,543		6,534		403,736		(148,843)		552,970

Total Great Lakes Dredge & Dock Corporation Equity		616,935		3,262		273,635		(620,197)		273,635
NONCONTROLLING INTERESTS		-		-		(210)		-		(210)
TOTAL EQUITY		616,935		3,262		273,425		(620,197)		273,425
TOTAL	$	908,478	$	9,796	$	677,161	$	(769,040)	$	826,395

Condensed Consolidating of Operations and Comprehensive Income


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
FOR THE THREE MONTHS ENDED MARCH 31, 2013
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

Contract revenues	$	185,419	$	3,759	$	-	$	(331)	$	188,847
Costs of contract revenues		(159,932)		(3,463)		-		331		(163,064)
Gross profit		25,487		296		-		-		25,783

OPERATING EXPENSES:
General and administrative expenses		18,996		191		-		-		19,187
(Gain) loss on sale of assets—net		2		-		-		-		2
Operating income (loss)		6,489		105		-		-		6,594

Interest expense—net		(19)		(42)		(5,672)		-		(5,733)
Equity in earnings (loss) of subsidiaries		(47)		-		9,556		(9,509)		-
Equity in earnings of joint ventures		(590)		-		-		-		(590)
Gain on foreign currency transactions—net		36		-		-		-		36

Income (loss) before income taxes		5,869		63		3,884		(9,509)		307

Income tax (provision) benefit		3,577		-		(3,473)		-		104

Net income (loss)		9,446		63		411		(9,509)		411
Net loss attributable to noncontrolling interests		-		-		22		-		22
Net income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	9,446	$	63	$	433	$	(9,509)	$	433


Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	9,463	$	57	$	444	$	(9,520)	$	444


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
FOR THE THREE MONTHS ENDED MARCH 31, 2012
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

Contract revenues	$	155,444	$	1,799	$	-	$	(2,336)	$	154,907
Costs of contract revenues		(135,167)		(2,054)		-		2,336		(134,885)
Gross profit		20,277		(255)		-		-		20,022

OPERATING EXPENSES:
General and administrative expenses		12,569		186		512		-		13,267
(Gain) loss on sale of assets—net		(42)		-		11		-		(31)
Operating income (loss)		7,750		(441)		(512)		-		6,786

Interest expense—net		(281)		(28)		(4,950)		-		(5,259)
Equity in earnings (loss) of subsidiaries		(379)		-		6,347		(5,968)		-
Equity in earnings of joint ventures		(16)		-		-		-		(16)
Loss on foreign currency transactions, net		6		-		-		-		6

Income (loss) before income taxes		7,080		(469)		885		(5,968)		1,517

Income tax (provision) benefit		(643)		-		79		-		(564)

Net income (loss)		6,437		(469)		964		(5,968)		953
Net income attributable to noncontrolling interests		-		-		115		-		115
Net income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	6,437	$	(469)	$	1,079	$	(5,968)	$	1,068

Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	$	6,911	$	(465)	$	1,546	$	(6,446)	$	1,546

Condensed Consolidating of Cash Flows


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE THREE MONTHS ENDED MARCH 31, 2012
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	$	(5,200)	$	801	$	(13,845)	$	-	$	(18,244)

INVESTING ACTIVITIES:
Purchases of property and equipment		(8,101)		-		-		-		(8,101)
Proceeds from dispositions of property and equipment		68		-		-		-		68

Net cash flows used in investing activities		(8,033)		-		-		-		(8,033)

FINANCING ACTIVITIES:
Dividends paid		-		-		(1,240)		-		(1,240)
Dividend equivalents paid on restricted stock units		-		-		(12)		-		(12)
Taxes paid on vested share awards		-		-		(2)				(2)
Net change in accounts with affiliates		(10,089)		(4,978)		15,067		-		-
Capital contributions		-		35		(35)		-		-
Repayments of equipment debt		(238)		-		-		-		(238)
Exercise of stock options		-		-		40		-		40
Excess income tax benefit from share-based compensation		-		-		27		-		27

Net cash flows provided by financing activities		(10,327)		(4,943)		13,845		-		(1,425)

Effect of foreign currency exchange rates on cash and cash equivalents		-		32		-		-		32

Net increase in cash and cash equivalents		(23,560)		(4,110)		-		-		(27,670)

Cash and cash equivalents at beginning of period		108,985		4,303		-		-		113,288

Cash and cash equivalents at end of period	$	85,425	$	193	$	-	$	-	$	85,618


GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE THREE MONTHS ENDED MARCH 31, 2013
(In thousands)

	Subsidiary Guarantors		Non-Guarantor Subsidiaries		GLDD Corporation		Eliminations		Consolidated Totals

OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	$	(10,786)	$	506	$	(2,952)	$	-	$	(13,232)

INVESTING ACTIVITIES:
Purchases of property and equipment		(15,514)		-		-		-		(15,514)
Proceeds from dispositions of property and equipment		58		-		-		-		58

Net cash flows used in investing activities		(15,456)		-		-		-		(15,456)

FINANCING ACTIVITIES:
Repayments of long term note payable		-		-		(10,547)		-		(10,547)
Taxes paid on settlement of vested share awards		-		-		(28)		-		(28)
Net change in accounts with affiliates		8,331		(343)		(7,988)		-		-
Repayments of equipment debt		(25)		-		-		-		(25)
Excess income tax benefit from share-based compensation		-		-		15		-		15
Borrowings under revolving loans		-		-		79,500		-		79,500
Repayments of revolving loans		-		-		(58,000)		-		(58,000)

Net cash flows provided by (used in) financing activities		8,306		(343)		2,952		-		10,915

Effect of foreign currency exchange rates on cash and cash equivalents		-		(24)		-		-		(24)

Net decrease in cash and cash equivalents		(17,936)		139		-		-		(17,797)

Cash and cash equivalents at beginning of period		24,272		168		-		-		24,440

Cash and cash equivalents at end of period	$	6,336	$	307	$	-	$	-	$	6,643

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Consolidated Statements Of Operations [Abstract]
CONTRACT REVENUES	$ 188,847	$ 154,907	$ 154,907
COSTS OF CONTRACT REVENUES	163,064	134,885	134,885
GROSS PROFIT	25,783	20,022	20,022
OPERATING EXPENSES:
GENERAL AND ADMINISTRATIVE EXPENSES	19,187	13,267	13,267
GAIN ON SALE OF ASSETS-Net	2	(31)	(31)
Total operating income	6,594	6,786	6,786
OTHER EXPENSE:
Interest expense-net	(5,733)	(5,259)	(5,259)
Equity in earnings (loss) of joint ventures	(590)	(16)	(16)
Loss on foreign currency transactions-net	36	6	6
INCOME BEFORE INCOME TAXES	307	1,517	1,517
INCOME TAX PROVISION	104	(564)	(564)
NET INCOME	411	953	953
Net (income) loss attributable to noncontrolling interests	22	115	115
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OF GREAT LAKES DREDGE & DOCK CORPORATION	$ 433	$ 1,068	$ 1,068
Basic earnings per share attributable to Great Lakes Dredge & Dock Corporation	$ 0.01	$ 0.02
Basic weighted average shares	59,369	59,038
Diluted earnings per share attributable to Great Lakes Dredge & Dock Corporation	$ 0.01	$ 0.02
Diluted weighted average shares	60,017	59,434

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Measurements [Abstract]

Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value


				Fair Value Measurements at Reporting Date Using
Description	At March 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)

Fuel hedge contracts	$	150	$	-	$	150	$	-

				Fair Value Measurements at Reporting Date Using
Description	At December 31, 2012		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)

Fuel hedge contracts	$	178	$	-	$	178	$	-

Schedule Fair Value Measurements Balance Sheet Location


		Fair Value at
		March 31,		December 31,
	Balance Sheet Location	2013		2012

Liability derivatives:
Derivatives designated as hedges
Fuel hedge contracts	Accrued expenses	$	150	$	178

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13467-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 19
-Subparagraph a, b, c(1), d(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 14
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15
-Subparagraph b-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph c(2), d, e, f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a, c(1), c(2), c(3), d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Fair Value Measurements (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2013 USD ($) $ / gal	Dec. 31, 2012 USD ($)	Jan. 31, 2011 USD ($)
Derivative underlying hedge percent	80.00%
Derivative, nonmonetary notional amount \| $ / gal	2.0
Senior Notes	$ 250,000	$ 250,000	$ 250,000
Reclassification of derivative losses to earnings-net of tax	(137)
Fair value hedge liabilities	$ 150	178
Senior notes interest rate	7.375%		7.375%
Maximum [Member]
Fixed price range \| $ / gal	3.26
Minimum [Member]
Fixed price range \| $ / gal	3.01
Parent Company [Member]
Senior Notes	$ 250,000	$ 250,000
Senior Notes [Member] \| Fair Value, Inputs, Level 1 [Member]
Senior Notes	$ 263,750

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
OPERATING ACTIVITIES:
Net income	$ 411	$ 953
Adjustments to reconcile net income to net cash flows used in operating activities:
Depreciation and amortization	12,075	7,764
Equity in (earnings) loss of joint ventures	590	16
Deferred income taxes	(2,585)	107
Gain on dispositions of property and equipment	2	(31)
Amortization of deferred financing fees	288	334
Unrealized foreign currency loss	41	(133)
Share-based compensation expense	751	1,015
Excess income tax benefit from share based compensation	(15)	(27)
Changes in assets and liabilities:
Accounts receivable	8,408	(1,842)
Contract revenues in excess of billings	(4,351)	(5,819)
Inventories	3,066	(1,869)
Prepaid expenses and other current assets	1,343	(7,399)
Accounts payable and accrued expenses	(30,695)	(21,263)
Billings in excess of contract revenues	(1,751)	10,126
Other noncurrent assets and liabilities	(810)	(176)
Net cash flows provided by (used in) by operating activities	(13,232)	(18,244)
INVESTING ACTIVITIES:
Purchases of property and equipment	(15,514)	(8,101)
Proceeds from dispositions of property and equipment	58	68
Net cash flows used in investing activities	(15,456)	(8,033)
FINANCING ACTIVITIES:
Repayment of long term note payable	(10,547)
Dividends paid		(1,240)
Dividend equivalents paid on restricted stock units		(12)
Taxes paid on settlement of vested share awards	(28)	(2)
Repayments of equipment debt	(25)	(238)
Exercise of stock options		40
Excess income tax benefit from share-based compensation	15	27
Borrowings under revolving loans	79,500
Repayments of revolving loans	(58,000)
Net cash flows provided by (used in) financing activities	10,915	(1,425)
Effect of foreign currency exchange rates on cash and cash equivalents	(24)	32
Net increase (decrease) in cash and cash equivalents	(17,797)	(27,670)
Cash and cash equivalents at beginning of period	24,440	24,440
Cash and cash equivalents at end of period	6,643	85,618
Supplemental Cash Flow Information
Cash paid for interest	9,881	9,582
Cash paid (refunded) for income taxes	241	(2,926)
Non-cash Investing and Financing Activities
Property and equipment purchased but not yet paid	$ 6,253	$ 4,957

Earnings Per Share

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Earnings Per Share

2. Earnings per share

Basic earnings per share is computed by dividing net income attributable to common stockholders by the weighted-average number of common shares outstanding during the reporting period. Diluted earnings per share is computed similar to basic earnings per share except that it reflects the potential dilution that could occur if dilutive securities or other obligations to issue common stock were exercised or converted into common stock. For the three months ended March 31, 2013 and 2012, zero options to purchase shares of common stock were excluded from the calculation of diluted earnings per share based on the application of the treasury stock method. The computations for basic and diluted earnings per share from continuing operations are as follows:


	Three Months Ended
	March 31,
	2013		2012
Net income attributable to common shareholders of Great Lakes Dredge & Dock Corporation	$	433	$	1,068

Weighted-average common shares outstanding — basic		59,369		59,038
Effect of stock options and restricted stock units		648		396

Weighted-average common shares outstanding — diluted		60,017		59,434

Earnings per share — basic	$	0.01	$	0.02
Earnings per share — diluted	$	0.01	$	0.02

Fair Value Measurements (Fair Value Measurements at Reporting Date Using) (Details) - Fuel Hedge Contracts [Member] - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012
Liabilities, fair value disclosure	$ 150	$ 178
Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure	$ 150	$ 178

Accounts Receivable And Contracts In Progress (Components Of Contracts In Progress) (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Costs and earnings in excess of billings on contracts in progress	$ 66,514	$ 65,890
Costs and earnings in excess of billings for completed contracts	7,402	3,684
Total contract revenues in excess of billings	73,916	69,574
Current portion of contract revenues in excess of billings	73,916	69,574
Total billings in excess of contract revenues	(9,529)	(11,280)
Costs And Earnings In Excess Of Billings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Costs and earnings for contracts in progress	346,231	458,750
Amounts billed	(279,717)	(392,860)
Billings In Excess Of Costs And Earnings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Costs and earnings for contracts in progress	367,272	327,461
Amounts billed	$ (376,801)	$ (338,741)

Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Statements Of Comprehensive Income [Abstract]
Currency translation adjustment, tax	$ (4)	$ 0	$ 3	$ 0	$ (3)	$ 0
Net unrealized gain on derivatives-net of tax	$ 11	(56)	$ 315	(295)	(231)	(830)
Change in fair value of derivatives, tax		$ 549		$ (246)	$ (132)	$ (313)

- Definition

Amount of tax effect, net of reclassification adjustments, on the result from the process of expressing in the reporting currency of the reporting entity those amounts that are denominated or measured in a different currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 20
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6915805&loc=d3e32211-110900

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e640-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 25
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 52
-Paragraph 31
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 23, 24, 25, 26
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Tax effect of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

+ References + Details

Subsidiary Guarantors (Condensed Consolidated of Cash Flow) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2011
OPERATING ACTIVITIES:
Net cash flows provided by (used in) by operating activities	$ (13,232)	$ (18,244)	$ (18,244)
INVESTING ACTIVITIES:
Purchases of property and equipment	(15,514)	(8,101)	(8,101)
Proceeds from dispositions of property and equipment	58	68	68
Net cash flows used in investing activities	(15,456)	(8,033)	(8,033)
FINANCING ACTIVITIES:
Repayment of long term note payable	(10,547)
Dividends paid		(1,240)	(1,240)
Dividend equivalents paid on restricted stock units		(12)	(12)
Taxes paid on settlement of vested share awards	(28)	(2)	(2)
Repayments of equipment debt	(25)	(238)	(238)
Exercise of stock options		40	40
Borrowings under revolving loans	79,500
Repayments of revolving loans	(58,000)
Excess income tax benefit from share-based compensation	15	27	27
Net cash flows provided by (used in) financing activities	10,915	(1,425)	(1,425)
Effect of foreign currency exchange rates on cash and cash equivalents	(24)	32	32
Net increase (decrease) in cash and cash equivalents	(17,797)	(27,670)	(27,670)
Cash and cash equivalents at beginning of period	24,440	24,440	113,288
Cash and cash equivalents at end of period	6,643	85,618	85,618
Parent Company [Member]
OPERATING ACTIVITIES:
Net cash flows provided by (used in) by operating activities	(2,952)		(13,845)
FINANCING ACTIVITIES:
Dividends paid			(1,240)
Dividend equivalents paid on restricted stock units			(12)
Taxes paid on settlement of vested share awards	(28)		(2)
Net change in accounts with affiliates	(7,988)		15,067
Capital contributions			(35)
Exercise of stock options			40
Excess income tax benefit from share-based compensation	15		27
Net cash flows provided by (used in) financing activities	2,952		13,845
Subsidiary Guarantors [Member]
OPERATING ACTIVITIES:
Net cash flows provided by (used in) by operating activities	(10,786)		(5,200)
INVESTING ACTIVITIES:
Purchases of property and equipment	(15,514)		(8,101)
Proceeds from dispositions of property and equipment	58		68
Net cash flows used in investing activities	(15,456)		(8,033)
FINANCING ACTIVITIES:
Net change in accounts with affiliates	8,331		(10,089)
Repayments of equipment debt	(25)		(238)
Net cash flows provided by (used in) financing activities	8,306		(10,327)
Net increase (decrease) in cash and cash equivalents	(17,936)		(23,560)
Cash and cash equivalents at beginning of period	24,272	24,272	108,985
Cash and cash equivalents at end of period	6,336		85,425
Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash flows provided by (used in) by operating activities	506		801
FINANCING ACTIVITIES:
Net change in accounts with affiliates	(343)		(4,978)
Capital contributions			35
Net cash flows provided by (used in) financing activities	(343)		(4,943)
Effect of foreign currency exchange rates on cash and cash equivalents	(24)		32
Net increase (decrease) in cash and cash equivalents	139		(4,110)
Cash and cash equivalents at beginning of period	168	$ 168	4,303
Cash and cash equivalents at end of period	$ 307		$ 193

Fair Value Measurement ( Other Comprehensive Income to Earnings) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Costs of contract revenues	$ 163,064	$ 134,885	$ 134,885
Income tax provision	(104)	564	564
Net income	411	953	953
Parent Company [Member]
Income tax provision	3,473		(79)
Net income	411		$ 964
Fuel Hedge Contracts [Member]
Costs of contract revenues	228	(675)
Income tax provision	(91)	269
Net income	$ 137	$ (406)

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

+ Details

Commitments And Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Jan. 31, 2011
Letters of credit outstanding	$ 33,420
Letter of credit remaining borrowing capacity	$ 120,080
Senior notes interest rate	7.375%			7.375%
Outstanding performance bonds	$ 612,677
Revenue value remaining from outstanding performance bonds	186,754
Senior Notes	250,000	$ 250,000		$ 250,000
Maximum [Member]
Bids bond range	10,000
Judgement			$ 13,272
Minimum [Member]
Bids bond range	1,000
Judgement			$ 11,736
Parent Company [Member]
Senior Notes	$ 250,000	$ 250,000

Nature Of Business And Summary Of Signicant Accounting Policies	3 Months Ended
	Mar. 31, 2013
Nature Of Business And Summary Of Significant Accounting Policies [Abstract]
Basis Of Presentation	1. Basis of presentation The unaudited condensed consolidated financial statements and notes herein should be read in conjunction with the audited consolidated financial statements of Great Lakes Dredge & Dock Corporation and its subsidiaries (the “Company” or “Great Lakes”) and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. The condensed consolidated financial statements included herein have been prepared by the Company without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to the SEC’s rules and regulations, although management believes that the disclosures are adequate and make the information presented not misleading. In the opinion of management, all adjustments, which are of a normal and recurring nature (except as otherwise noted), that are necessary to present fairly the Company’s financial position as of March 31, 2013, and its results of operations for the three months ended March 31, 2013 and 2012 and cash flows for the three months ended March 31, 2013 and 2012 have been included. The components of costs of contract revenues include labor, equipment (including depreciation, maintenance, insurance and long-term rentals), subcontracts, fuel and project overhead. Hourly labor is generally hired on a project-by-project basis. Costs of contract revenues vary significantly depending on the type and location of work performed and assets utilized. Generally, capital projects have the highest margins due to the complexity of the projects, while coastal protection projects have the most volatile margins because they are most often exposed to variability in weather conditions. The Company’s cost structure includes significant annual equipment-related costs, including depreciation, maintenance, insurance and long-term rentals. These costs have averaged approximately 20% to 23% of total costs of contract revenues over the prior three years. During the year, both equipment utilization and the timing of fixed cost expenditures fluctuate significantly. Accordingly, the Company allocates these fixed equipment costs to interim periods in proportion to revenues recognized over the year, to better match revenues and expenses. Specifically, at each interim reporting date the Company compares actual revenues earned to date on its dredging contracts to expected annual revenues and recognizes equipment costs on the same proportionate basis. In the fourth quarter, any over or under allocated equipment costs are recognized such that the expense for the year equals actual equipment costs incurred during the year. The Company operates in four operating segments that, through aggregation, comprise two reportable segments: dredging and demolition. Four operating segments were aggregated into two reportable segments as the segments have similarity in economic margins, services, production processes, customer types, distribution methods and regulatory environment. The Company has determined that the operating segments are the Company’s four reporting units. The condensed consolidated results of operations and comprehensive income for the interim periods presented herein are not necessarily indicative of the results to be expected for the full year.

- Definition

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

+ References + Details

Subsidiary Guarantors (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012	Jan. 31, 2011
Subsidiary Guarantors [Abstract]
Senior Notes	$ 250,000	$ 250,000	$ 250,000
Senior notes interest rate	7.375%		7.375%

Fair Value Measurements (Balance Sheet Location) (Details) - USD ($) $ in Thousands	Mar. 31, 2013	Dec. 31, 2012
Fuel Hedge Contracts [Member] \| Designated as Hedging Instrument [Member] \| Accrued Liabilities [Member]
Derivative asset, fair value, gross liability	$ 150	$ 178

Accounts Receivable And Contracts In Progress

3 Months Ended

Mar. 31, 2013

Accounts Receivable And Contracts In Progress [Abstract]

Accounts Receivables And Contracts In Progress

3. Accounts receivable and contracts in progress

Accounts receivable at March 31, 2013 and December 31, 2012 are as follows:


	March 31,		December 31,
	2013		2012
Completed contracts	$	56,984	$	43,898
Contracts in progress		74,653		91,459
Retainage		20,119		24,419
		151,756		159,776
Allowance for doubtful accounts		(2,469)		(2,050)

Total accounts receivable—net	$	149,287	$	157,726

Current portion of accounts receivable—net	$	141,250	$	149,142
Long-term accounts receivable and retainage		8,037		8,584
Total accounts receivable—net	$	149,287	$	157,726

The components of contracts in progress at March 31, 2013 and December 31, 2012 are as follows:


	March 31,		December 31,
	2013		2012
Costs and earnings in excess of billings:
Costs and earnings for contracts in progress	$	346,231	$	458,750
Amounts billed		(279,717)		(392,860)
Costs and earnings in excess of billings for contracts in progress		66,514		65,890

Costs and earnings in excess of billings for completed contracts		7,402		3,684

Total contract revenues in excess of billings	$	73,916	$	69,574

Billings in excess of costs and earnings:
Amounts billed	$	(376,801)	$	(338,741)
Costs and earnings for contracts in progress		367,272		327,461

Total billings in excess of contract revenues	$	(9,529)	$	(11,280)

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5066-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3,4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5162-111524

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5074-111524

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 01-6
-Paragraph 13
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 3, 4
-Article 5

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 7
-Article 9

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph k
-Article 4

+ Details