Great Lakes Dredge & Dock (GLDD) 10-K 1 Mar 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	GLDD
Entity Registrant Name	Great Lakes Dredge & Dock CORP
Entity Central Index Key	1,372,020
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		61,619,680
Entity Public Float			$ 257,204,723
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 15,852	$ 11,167
Accounts receivable—net	75,533	88,091
Contract revenues in excess of billings	90,788	95,012
Inventories	34,600	37,137
Prepaid expenses	5,183	12,407
Other current assets	40,228	63,412
Total current assets	262,184	307,226
PROPERTY AND EQUIPMENT—Net	407,294	413,008
GOODWILL	83,576	83,576
OTHER INTANGIBLE ASSETS — Net	908	1,499
INVENTORIES—Noncurrent	54,023	52,602
INVESTMENTS IN JOINT VENTURES	2,714	4,734
ASSETS HELD FOR SALE— Noncurrent	8,530	9,299
OTHER	13,128	21,644
TOTAL	832,357	893,588
LIABILITIES AND EQUITY
Accounts payable	87,659	103,185
Accrued expenses	56,218	69,043
Billings in excess of contract revenues	3,615	5,141
Current portion of long-term debt	2,758	2,465
Total current liabilities	150,250	179,834
LONG-TERM DEBT	333,141	286,291
REVOLVING CREDIT FACILITY	95,000	104,111
DEFERRED INCOME TAXES	25,561	68,449
OTHER	7,109	7,013
Total liabilities	611,061	645,698
COMMITMENTS AND CONTINGENCIES (Note 14)
EQUITY:
Common stock—$.0001 par value; 90,000 authorized, 61,897 and 61,240 shares issued; 61,619 and 60,962 outstanding at December 31, 2017 and December 31, 2016, respectively.	6	6
Treasury stock, at cost	(1,433)	(1,433)
Additional paid-in capital	289,821	286,303
Accumulated deficit	(67,101)	(35,841)
Accumulated other comprehensive income (loss)	3	(1,145)
Total equity	221,296	247,890
TOTAL	$ 832,357	$ 893,588

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	61,897,000	61,240,000
Common stock, shares outstanding	61,619,000	60,962,000

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
CONTRACT REVENUES	$ 702,503	$ 767,585	$ 856,878
COSTS OF CONTRACT REVENUES	652,620	681,197	760,955
GROSS PROFIT	49,883	86,388	95,923
OPERATING EXPENSES:
GENERAL AND ADMINISTRATIVE EXPENSES	68,331	65,533	71,069
IMPAIRMENT OF GOODWILL	0		2,750
(GAIN) LOSS ON SALE OF ASSETS—Net	5,077	6,175	(855)
Total operating income (loss)	(23,525)	14,680	22,959
OTHER EXPENSE:
Interest expense—net	(26,046)	(22,907)	(24,365)
Equity in loss of joint ventures	(1,484)	(2,365)	(6,051)
Loss on extinguishment of debt	(2,330)
Other expense	(788)	(3,377)	(1,229)
Total other expense	(30,648)	(28,649)	(31,645)
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(54,173)	(13,969)	(8,686)
INCOME TAX BENEFIT	35,610	5,792	2,497
LOSS FROM CONTINUING OPERATIONS	(18,563)	(8,177)	(6,189)
Loss from discontinued operations, net of income taxes	(12,697)
NET LOSS	$ (31,260)	$ (8,177)	$ (6,189)
Basic loss per share attributable to loss from continuing operations	$ (0.30)	$ (0.13)	$ (0.10)
Basic loss per share attributable to loss on discontinued operations, net of income taxes	(0.21)
Basic loss per share	$ (0.51)	$ (0.13)	$ (0.10)
Basic weighted average shares	61,365	60,744	60,410
Diluted loss per share attributable to loss from continuing operations	$ (0.30)	$ (0.13)	$ (0.10)
Diluted loss per share attributable to loss on discontinued operations, net of income taxes	(0.21)
Diluted loss per share	$ (0.51)	$ (0.13)	$ (0.10)
Diluted weighted average shares	61,365	60,744	60,410

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (31,260)	$ (8,177)	$ (6,189)
Currency translation adjustment—net of tax	[1]	(41)	508	(1,249)
Net unrealized loss on derivatives—net of tax	[2]	1,189	330
Other comprehensive income (loss)—net of tax		1,148	838	(1,249)
Comprehensive loss		$ (30,112)	$ (7,339)	$ (7,438)
[1]	Net of income tax (provision) benefit of $44, $(338) and $827 for the years ended December 31, 2017, 2016 and 2015, respectively.
[2]	Net of income tax benefit of $1,048 and $216 for the years ended December 31, 2017 and 2016, respectively.

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Currency translation adjustment, tax	$ 44	$ (338)	$ 827
Net unrealized loss on derivatives, tax	$ 1,048	$ 216

Consolidated Statements Of Equi

Consolidated Statements Of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
BALANCE - value at Dec. 31, 2014	$ 255,963	$ 6		$ 278,166	$ (21,475)	$ (734)
BALANCE - shares at Dec. 31, 2014		60,170
Share-based compensation, Value	4,040			4,040
Share-based compensation, Shares		154
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(267)			(267)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		115
Exercise of stock options and purchases from employee stock plan, Value	1,365			1,365
Exercise of stock options and purchases from employee stock plan, Shares		270
Excess income tax benefit from share-based compensation	(57)			(57)
Purchase of treasury stock, value	(1,433)		$ (1,433)
Purchase of treasury stock, shares			(278)
Net loss	(6,189)				(6,189)
Other comprehensive income (loss)—net of tax	(1,249)					(1,249)
BALANCE - value at Dec. 31, 2015	252,173	$ 6	$ (1,433)	283,247	(27,664)	(1,983)
BALANCE - shares at Dec. 31, 2015		60,709	(278)
Share-based compensation, Value	2,455			2,455
Share-based compensation, Shares		148
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(171)			(171)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		74
Exercise of stock options and purchases from employee stock plan, Value	905			905
Exercise of stock options and purchases from employee stock plan, Shares		309
Excess income tax benefit from share-based compensation	(133)			(133)
Net loss	(8,177)				(8,177)
Other comprehensive income (loss)—net of tax	838					838
BALANCE - value at Dec. 31, 2016	247,890	$ 6	$ (1,433)	286,303	(35,841)	(1,145)
BALANCE - shares at Dec. 31, 2016		61,240	(278)
Share-based compensation, Value	2,963			2,963
Share-based compensation, Shares		248
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(328)			(328)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		147
Exercise of stock options and purchases from employee stock plan, Value	$ 883			883
Exercise of stock options and purchases from employee stock plan, Shares	4	262
Net loss	$ (31,260)				(31,260)
Other comprehensive income (loss)—net of tax	1,148					1,148
BALANCE - value at Dec. 31, 2017	$ 221,296	$ 6	$ (1,433)	$ 289,821	$ (67,101)	$ 3
BALANCE - shares at Dec. 31, 2017		61,897	(278)

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES:
Net loss	$ (31,260)	$ (8,177)	$ (6,189)
Loss from discontinued operations, net of income taxes	(12,697)
Loss from continuing operations	(18,563)	(8,177)	(6,189)
Adjustments to reconcile net loss to net cash flows provided by operating activities:
Depreciation and amortization	60,520	63,023	64,585
Equity in (earnings) loss of joint ventures	(5,008)	(4,494)	771
Loss on extinguishment of 7 3/8% senior subordinated notes	2,330
Cash distributions from joint ventures	8,486	5,129	8,384
Deferred income taxes	(34,684)	(6,109)	(2,689)
(Gain) loss on dispositions of property and equipment	5,077	6,175	(855)
Impairment of goodwill	0		2,750
Gain on adjustment of contingent consideration		(8,940)	(8,444)
Other non-cash restructuring items	15,678
Amortization of deferred financing fees	3,280	2,922	2,766
Unrealized foreign currency (gain) loss	(206)	477	(1,054)
Unrealized net (gain) loss from mark-to-market valuations of derivatives	1,747	(6,135)	1,359
Share-based compensation expense	2,963	2,455	4,040
Excess income tax benefit from share-based compensation		133	57
Changes in assets and liabilities:
Accounts receivable	12,544	41,274	(20,190)
Contract revenues in excess of billings	4,254	(13,554)	48
Inventories	(2,237)	(6,239)	(6,612)
Prepaid expenses and other current assets	(1,170)	(5,310)	(9,730)
Accounts payable and accrued expenses	(9,579)	(17,762)	306
Billings in excess of contract revenues	(1,347)	(2,002)	2,325
Other noncurrent assets and liabilities	(1,667)	(4,196)	(2,506)
Net cash flows provided by operating activities of continuing operations	42,418	38,670	29,122
Net cash flows used in operating activities of discontinued operations	(20,900)
Cash provided by operating activities	21,518	38,670	29,122
INVESTING ACTIVITIES:
Purchases of property and equipment	(68,229)	(83,798)	(74,455)
Proceeds from dispositions of property and equipment	10,077	18,257	1,322
Changes in restricted cash	7,035	(7,035)
Cash used in investing activities	(51,117)	(72,576)	(73,133)
FINANCING ACTIVITIES:
Proceeds from issuance of debt	326,241		3,050
Repayments of debt	(277,750)	(47,085)	(6,644)
7 3/8% senior notes tender premium	(744)
Deferred financing fees	(5,022)	(6,817)	(111)
Taxes paid on settlement of vested share awards	(328)	(171)	(267)
Exercise of stock options and purchases from employee stock plans	883	905	1,365
Excess income tax benefit from share-based compensation		(133)	(57)
Purchase of treasury stock			(1,433)
Borrowings under revolving loans	124,925	288,611	179,500
Repayments of revolving loans	(134,036)	(204,500)	(159,500)
Cash provided by financing activities	34,169	30,810	15,903
Effect of foreign currency exchange rates on cash and cash equivalents	115	79	(97)
Net increase (decrease) in cash and cash equivalents	4,685	(3,017)	(28,205)
Cash and cash equivalents at beginning of period	11,167	14,184	42,389
Cash and cash equivalents at end of period	15,852	11,167	14,184
Supplemental Cash Flow Information
Cash paid for interest	34,789	26,563	25,391
Cash paid for income taxes	365	200	586
Non-cash Investing and Financing Activities
Property and equipment purchased but not yet paid	$ 4,255	$ 8,795	7,380
Property and equipment purchased on capital leases and equipment notes			2,190
Property & equipment purchased on notes payable			$ 15,569

Consolidated Statements Of Cas9

Consolidated Statements Of Cash Flows (Parenthetical)	Dec. 31, 2017	Dec. 31, 2016
7 3/8% SENIOR NOTES [Member]
Debt instrument, interest rate, stated percentage	7.375%	7.375%

Nature Of Business And Summary

Nature Of Business And Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature Of Business And Summary Of Significant Accounting Policies	1. NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization —Great Lakes Dredge & Dock Corporation and its subsidiaries (the “Company” or “Great Lakes”) are in the business of marine construction, primarily dredging, and soil, water and sediment environmental and remediation services. The Company’s primary dredging customers are domestic and foreign government agencies, as well as private entities, and its environmental and remediation customers are general contractors, corporations, environmental engineering and construction firms that commission projects and local government and municipal agencies. Principles of Consolidation and Basis of Presentation —The consolidated financial statements include the accounts of Great Lakes Dredge & Dock Corporation and its majority-owned subsidiaries. All intercompany accounts and transactions are eliminated in consolidation. The equity method of accounting is used for investments in unconsolidated investees in which the Company has significant influence, but not control. Other investments, if any, are carried at cost. Use of Estimates —The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect certain reported amounts and disclosures. Accordingly, actual results could differ from those estimates. Revenue and Cost Recognition on Contracts —Substantially all of the Company’s contracts for dredging services are fixed-price contracts, which provide for remeasurement based on actual quantities dredged. The majority of the Company’s environmental & infrastructure contracts, previously referred to as environmental & remediation, are also fixed-price contracts, with others performed on a time-and-materials basis. Contract revenues are recognized under the percentage-of-completion method based on the Company’s engineering estimates of the physical percentage completed for dredging projects and based on costs incurred to date compared to total estimated costs for fixed-price environmental & infrastructure projects. For dredging projects, costs of contract revenues are adjusted to reflect the gross profit percentage expected to be achieved upon ultimate completion. For environmental & infrastructure contracts, contract revenues are adjusted to reflect the estimated gross profit percentage. Revisions in estimated gross profit percentages are recorded in the period during which the change in circumstances is experienced or becomes known. As the duration of most of the Company’s contracts is one year or less, the cumulative net impact of these revisions in estimates, individually and in the aggregate across our projects, does not significantly affect our results across annual reporting periods. Provisions for estimated losses on contracts in progress are made in the period in which such losses are determined. Change orders are not recognized in revenue until the recovery is probable and collectability is reasonably assured. Claims for additional compensation due to the Company are not recognized in contract revenues until such claims are settled. Billings on contracts are generally submitted after verification with the customers of physical progress and may not match the timing of revenue recognition. The difference between amounts billed and recognized as revenue is reflected in the balance sheet as either contract revenues in excess of billings or billings in excess of contract revenues. Modifications may be negotiated when a change from the original contract specification is encountered, and a change in project scope, performance methodology and/or material disposal is necessary. Thus, the resulting modification is considered a change in the scope of the original project to which it relates. Significant expenditures incurred incidental to major contracts are deferred and recognized as contract costs based on contract performance over the duration of the related project. These expenditures are reported as prepaid expenses. The components of costs of contract revenues include labor, equipment (including depreciation, maintenance, insurance and long-term rentals), subcontracts, fuel, supplies, short-term rentals and project overhead. Project costs, excluding labor, have averaged approximately 23% of total costs of contract revenues over the prior three years. Hourly labor generally is hired on a project-by-project basis. Much of our domestic dredging hourly labor force is represented by labor unions with collective bargaining agreements that expire at various dates during 2018 through 2023, which historically have been extended without disruption. The environmental & infrastructure segment’s hourly labor force is made up of union and non-union employees. During the year, both dredging 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 dredging revenues recognized over the year, to better match revenues and expenses. Specifically, at each interim reporting date the Company compares actual dredging revenues earned to date on the Company’s dredging contracts to expected annual revenues and recognizes dredging 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. As a result of this methodology, the recorded expense in any interim period may be higher or lower than the actual equipment costs incurred in that interim period. For some environmental & infrastructure contracts, the Company has entered into unincorporated construction joint ventures under which certain portions of a larger project are performed. These investments are accounted for under the proportionate consolidation method for income statement reporting and under the equity method for balance sheet reporting. The Company’s interests in any profits and assets and proportionate share in any losses and liabilities are recognized based on the Company’s stated percentage partnership interest in the project. For projects related to proportionately consolidated joint ventures, we include only the Company’s percentage ownership of each joint venture's backlog. Classification of Current Assets and Liabilities —The Company includes in current assets and liabilities amounts realizable and payable in the normal course of contract completion, unless completion of such contracts extends significantly beyond one year. Cash Equivalents —The Company considers all highly liquid investments with a maturity at purchase of three months or less to be cash equivalents. Accounts Receivable —Accounts receivable represent amounts due or billable under the terms of contracts with customers, including amounts related to retainage. The Company anticipates collection of retainage generally within one year, and accordingly presents retainage as a current asset. The Company provides an allowance for estimated uncollectible accounts receivable when events or conditions indicate that amounts outstanding are not recoverable. Inventories —Inventories consist of pipe and spare parts used in the Company’s dredging operations. Pipe and spare parts are purchased in large quantities; therefore, a certain amount of pipe and spare part inventories is not anticipated to be used within the current year and is classified as long-term. Spare part inventories are stated at weighted average historical cost, and are charged to expense when used in operations. Pipe inventory is recorded at cost and amortized to expense over the period of its use. Property and Equipment —Capital additions, improvements, and major renewals are classified as property and equipment and are carried at depreciated cost. Maintenance and repairs that do not significantly extend the useful lives of the assets or enhance the capabilities of such assets are charged to expenses as incurred. Depreciation is recorded over the estimated useful lives of property and equipment using the straight-line method and the mid-year depreciation convention. The estimated useful lives by class of assets are: Class Useful Life (years) Buildings and improvements 10 Furniture and fixtures 5-10 Vehicles, dozers, and other light operating equipment and systems 3-5 Heavy operating equipment (dredges and barges) 10-30 Leasehold improvements are amortized over the shorter of their remaining useful lives or the remaining terms of the leases. Goodwill and Other Intangible Assets —Goodwill represents the excess of acquisition cost over fair value of the net assets acquired. Other identifiable intangible assets mainly represent developed technology and databases, customer relationships, and customer contracts acquired in business combinations and are being amortized over a one to five-year period. Goodwill is tested annually for impairment in the third quarter of each year, or more frequently should circumstances dictate. GAAP requires that goodwill of a reporting unit be tested for impairment between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The Company assesses the fair values of its reporting units using both a market-based approach and an income-based approach. Under the income approach, the fair value of the reporting unit is based on the present value of estimated future cash flows. The income approach is dependent on a number of factors, including estimates of future market growth trends, forecasted revenues and expenses, appropriate discount rates and other variables. The estimates are based on assumptions that the Company believes to be reasonable, but such assumptions are subject to unpredictability and uncertainty. Changes in these estimates and assumptions could materially affect the determination of fair value, and may result in the impairment of goodwill in the event that actual results differ from those estimates. The market approach measures the value of a reporting unit through comparison to comparable companies. Under the market approach, the Company uses the guideline public company method by applying estimated market-based enterprise value multiples to the reporting unit’s estimated revenue and Adjusted EBITDA. The Company analyzes companies that performed similar services or are considered peers. Due to the fact that there are no public companies that are direct competitors, the Company weighs the results of this approach less than the income approach. The Company has two operating segments: dredging and environmental & infrastructure, which are also the Company’s two reportable segments and reporting units. Long-Lived Assets —Long-lived assets are comprised of property and equipment and intangible assets subject to amortization. Long-lived assets to be held and used are reviewed for possible impairment whenever events indicate that the carrying amount of such assets may not be recoverable by comparing the undiscounted cash flows associated with the assets to their carrying amounts. If such a review indicates an impairment, the carrying amount would be reduced to fair value. No triggering events were identified in 2017 or 2016. If long-lived assets are to be disposed, depreciation is discontinued, if applicable, and the assets are reclassified as held for sale at the lower of their carrying amounts or fair values less estimated costs to sell. Self-insurance Reserves —The Company self-insures costs associated with its seagoing employees covered by the provisions of Jones Act, workers’ compensation claims, hull and equipment liability, and general business liabilities up to certain limits. Insurance reserves are established for estimates of the loss that the Company may ultimately incur on reported claims, as well as estimates of claims that have been incurred but not yet reported. In determining its estimates, the Company considers historical loss experience and judgments about the present and expected levels of cost per claim. Trends in actual experience are a significant factor in the determination of such reserves. Income Taxes —The provision for income taxes includes federal, foreign, and state income taxes currently payable and those deferred because of temporary differences between the financial statement and tax basis of assets and liabilities. Recorded deferred income tax assets and liabilities are based on the estimated future tax effects of differences between the financial and tax basis of assets and liabilities, given the effect of currently enacted tax laws. The Company’s current policy is to repatriate all earnings from foreign subsidiaries’ operations as generated and at this time no amounts are considered to be permanently reinvested in those operations. On December 22, 2017, the U.S. government enacted comprehensive tax legislation referred to as the Tax Cuts and Jobs Act. See Note 10. Hedging Instruments —At times, the Company designates certain derivative contracts as a cash flow hedge as defined by GAAP. Accordingly, the Company formally documents, at the inception of each hedge, all relationships between hedging instruments and hedged items, as well as our risk-management objective and strategy for undertaking hedge transactions. This process includes linking all derivatives to highly-probable forecasted transactions. The Company formally assesses, at inception and on an ongoing basis, the effectiveness of hedges in offsetting changes in the cash flows of hedged items. Hedge accounting treatment may be discontinued when (1) it is determined that the derivative is no longer highly effective in offsetting changes in the cash flows of a hedged item (including hedged items for forecasted future transactions), (2) the derivative expires or is sold, terminated or exercised, (3) it is no longer probable that the forecasted transaction will occur or (4) management determines that designating the derivative as a hedging instrument is no longer appropriate. If management elects to stop hedge accounting, it would be on a prospective basis and any hedges in place would be recognized in accumulated other comprehensive income (loss) until all the related forecasted transactions are completed or are probable of not occurring. Foreign Currency Translation —The financial statements of the Company’s foreign subsidiaries where the operations are primarily denominated in the foreign currency are translated into U.S. dollars for reporting. Balance sheet accounts are translated at the current foreign exchange rate at the end of each period and income statement accounts are translated at the average foreign exchange rate for each period. Gains and losses on foreign currency translations are reflected as a currency translation adjustment, net of tax, in accumulated other comprehensive income (loss). Foreign currency transaction gains and losses are included in other income (expense). Recent Accounting Pronouncements —In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update No. 2017-04 (“ASU 2017-04”), Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . The amendment removes the requirement to compare the implied fair value of goodwill with its carrying amount as part of step 2 of the goodwill impairment test. The guidance is effective for fiscal years beginning after December 15, 2019. The Company does not anticipate that the adoption of ASU 2017-04 will have a material effect on the Company’s consolidated financial statements. In November 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update No. 2016-18 (“ASU 2016-18”), Statement of Cashflows (Topic 230): Restricted Cash. The Company does not anticipate that the adoption of ASU 2016-18 will have a material effect on the Company’s consolidated financial statements. In August 2016, the FASB issued Accounting Standard Update No. 2016-15 (“ASU 2016-15”), Classification of Certain Cash Receipts and Cash Payments The Company does not anticipate that the adoption of ASU 2016-15 will have a material effect on the Company’s consolidated financial statements. In February 2016, the FASB issued Accounting Standard Update No. 2016-02 (“ASU 2016-02”), Leases (Topic 842) In May 2014, the FASB issued Accounting Standard Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) Accounting Standard Updates related to Accounting Standards Codification Topic 606 (collectively, “ASC 606”)

Earnings Per share

Earnings Per share	12 Months Ended
	Dec. 31, 2017
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 years ended December 31, 2017, 2016 and 2015 the dilutive effect of 716 thousand, 623 thousand and 431 thousand stock options (“NQSO”) and restricted stock units (“RSU”), respectively, were excluded from the diluted weighted-average common shares outstanding as the Company incurred a loss during these periods. For the years ended December 31, 2017, 2016 and 2015 2,476 thousand, 1,594 thousand and 1,179 thousand NQSOs and RSUs, respectively, were excluded from the calculation of diluted earnings per share based on the application of the treasury stock method, as such NQSOs and RSUs were determined to be anti-dilutive. The computations for basic and diluted loss per share for the years ended December 31, 2017, 2016 and 2015 are as follows: (shares in thousands) 2017 2016 2015 Loss from continuing operations $ (18,563 ) $ (8,177 ) $ (6,189 ) Loss on discontinued operations, net of income taxes, attributable to Great Lakes Dredge & Dock Corporation (12,697 ) — — Net loss attributable to common stockholders of Great Lakes Dredge & Dock Corporation $ (31,260 ) $ (8,177 ) $ (6,189 ) Weighted-average common shares outstanding — basic 61,365 60,744 60,410 Effect of stock options and restricted stock units — — — Weighted-average common shares outstanding — diluted 61,365 60,744 60,410 Loss per share from continuing operations — basic $ (0.30 ) $ (0.13 ) $ (0.10 ) Loss per share from continuing operations — diluted $ (0.30 ) $ (0.13 ) $ (0.10 )

Restricted And Escrowed Cash

Restricted And Escrowed Cash	12 Months Ended
	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Restricted And Escrowed Cash	3. RESTRICTED AND ESCROWED CASH At December 31, 2017, the Company had restricted cash of $3,742, of which $1,500 was included in other noncurrent assets and $2,242 was included in other current assets. Restricted cash included in other noncurrent assets relates to cash held in escrow as security for the Company’s lease rental obligation under a long-term equipment operating lease. Restricted cash included in other current assets relates to cash held in escrow related to an outstanding lawsuit at our historical demolition business. At December 31, 2016, the Company had restricted cash of $10,777 of which $8,535 was included in other noncurrent assets and $2,242 was included in other current assets. Restricted cash included in other noncurrent assets relates to $7,035 of cash collateral issued for two letters of credit in connection with the termination of the Company’s former revolving credit agreement and $1,500 relates to cash held in escrow as security for the Company’s lease rental obligation under a long-term equipment operating lease. Restricted cash included in other current assets relates to cash held in escrow related to an outstanding lawsuit at our historical demolition business.

Accounts Receivable And Contrac

Accounts Receivable And Contracts In Progress	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Accounts receivable and contracts in progress	4. ACCOUNTS RECEIVABLE AND CONTRACTS IN PROGRESS Accounts receivable at December 31, 2017 and 2016 are as follows: 2017 2016 Completed contracts $ 15,974 $ 18,727 Contracts in progress 42,759 53,137 Retainage 21,866 21,399 80,599 93,263 Allowance for doubtful accounts (591 ) (747 ) Total accounts receivable—net $ 80,008 $ 92,516 Current portion of accounts receivable—net $ 75,533 $ 88,091 Long-term accounts receivable and retainage 4,475 4,425 Total accounts receivable—net $ 80,008 $ 92,516 The components of contracts in progress at December 31, 2017 and 2016 are as follows: 2017 2016 Costs and earnings in excess of billings: Costs and earnings for contracts in progress $ 558,557 $ 587,371 Amounts billed (490,732 ) (511,548 ) Costs and earnings in excess of billings for contracts in progress 67,825 75,823 Costs and earnings in excess of billings for completed contracts 22,963 19,189 Total contract revenues in excess of billings $ 90,788 $ 95,012 Billings in excess of costs and earnings: Amounts billed $ (325,350 ) $ (268,754 ) Costs and earnings for contracts in progress 321,735 263,613 Total billings in excess of contract revenues $ (3,615 ) $ (5,141 ) The Company has $17,860 included in costs in excess of billings that are dependent upon the sale of environmental credits earned for a wetland mitigation project. The sale of these credits is subject to market factors that could cause the amount of expected revenue to be higher or lower than currently estimated. If the amount of proceeds received from the sale of the environmental credits is lower than our expectations, we could sustain a loss of part or all of costs incurred related to this project. Additionally, the timing of realization may be impacted by the timing of a delay in the sale of these environmental credits, requiring a longer period required to recover our investment.

Property And Equipment

Property And Equipment	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Property And Equipment	5. PROPERTY AND EQUIPMENT Property and equipment at December 31, 2017 and 2016 are as follows: 2017 2016 Land $ 9,992 $ 9,992 Buildings and improvements 5,092 5,133 Furniture and fixtures 12,990 11,998 Operating equipment 805,748 788,989 Total property and equipment 833,822 816,112 Accumulated depreciation (426,528 ) (403,104 ) Property and equipment — net $ 407,294 $ 413,008 Operating equipment of $8,530 and $9,299 was classified as held for sale, excluded from property and equipment, as of December 31, 2017 and 2016, respectively. A $2,330 and $2,744 loss was recorded to (gain) loss on sale of assets—net for held for sale assets reclassified from property and equipment representing the fair value less cost to sell for the years ended December 31, 2017 and 2016, respectively. Depreciation expense was $59,927, $61,694 and $58,050, for the years ended December 31, 2017, 2016 and 2015, respectively. For more information about changes in assets held for sale and depreciation expense related to the Company’s restructuring refer to Note 13, Restructuring Charges.

Goodwill And Other Intangible A

Goodwill And Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill And Other Intangible Assets	6. The Company’s annual goodwill impairment test is conducted in the third quarter of each year and interim evaluations are performed when the Company determines that a triggering event has occurred that would more likely than not reduce the fair value of goodwill below its carrying value. The Company performed its annual goodwill impairment test as of July 1, 2017 with no indication of impairment. As of the test date, the fair value of the remaining reporting units was in excess of their carrying values. The Company will perform its next scheduled annual test of goodwill in the third quarter of 2018 should no triggering events occur which would require a test prior to the next annual test. During 2015, due to a decline in the overall financial performance and declining cash flows in the Terra reporting unit, the Company concluded there was a triggering event that required an interim goodwill impairment test for the reporting unit. The Company performed step one of the goodwill impairment test as of June 30, 2015, which compared the fair value of the Terra reporting unit against its carrying amount, including goodwill. In deriving the fair value of the Terra reporting unit, the Company used both a market-based approach and an income-based approach. Under the income approach, the fair value of the reporting unit is based on the present value of estimated future cash flows. Under the market approach, the Company uses the guideline public company method by applying estimated market-based enterprise value multiples to the reporting unit’s estimated revenue and Adjusted EBITDA from continuing operations. Based on the first step analysis, management concluded that the fair value of the Terra reporting unit was less than its carrying value; therefore, the Company performed step two of the goodwill impairment analysis. Step two of the goodwill impairment analysis measures the impairment charge by allocating the reporting unit’s fair value to all of the assets and liabilities of the reporting unit in a hypothetical analysis that calculates implied fair value of goodwill in the same manner as if the reporting unit was being acquired in a business combination. Any excess of the carrying value of the reporting unit’s goodwill over the implied fair value of the reporting unit’s goodwill is recorded as a loss on impairment of goodwill. Management determined that the Terra reporting unit’s implied fair value of goodwill was below the carrying value as of June 30, 2015. As a result, the Company recorded an impairment charge of $2,750 in the second quarter of 2015. The change in the carrying amount of goodwill during the years ended December 31, 2017 and 2016 is as follows: Dredgin g Environmental & Infrastructur e Total Balance - January 1, 2015 $ 76,576 $ 9,750 $ 86,326 Impairment of goodwill — (2,750 ) (2,750 ) Balance - December 31, 2016 76,576 7,000 83,576 Balance - December 31, 2017 $ 76,576 $ 7,000 $ 83,576 At December 31, 2017 and 2016, the net book value of identifiable intangible assets was as follows: As of December 31, 2017 Cost Accumulated Amortization Net Non-compete agreements $ 2,377 $ 1,753 $ 624 Other 781 497 284 $ 3,158 $ 2,250 $ 908 As of December 31, 2016 Non-compete agreements $ 2,377 $ 1,317 $ 1,060 Other 781 342 439 $ 3,158 $ 1,659 $ 1,499 Amortization expense was $591, $1,329 and $6,535, for the years ended December 31, 2017, 2016 and 2015, respectively, and is included as a component of general and administrative expenses. Amortization expense related to intangible assets is estimated to be $534 in 2018, $214 in 2019, $80 in 2020 and $80 in 2021.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued Expenses	7. ACCRUED EXPENSES Accrued expenses at December 31, 2017 and 2016 are as follows: 2017 2016 Insurance $ 22,941 $ 18,114 Payroll and employee benefits 8,747 10,028 Accrued rent 6,519 738 Interest 4,210 8,660 Percentage of completion adjustment 3,591 3,322 Income and other taxes 2,794 3,208 Accumulated deficit in joint venture — 17,016 Other 7,416 7,957 Total accrued expenses $ 56,218 $ 69,043

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt	8. LONG-TERM DEBT Long-term debt at December 31, 2017 and 2016 is as follows: 2017 2016 Revolving credit facility $ 95,000 $ 104,111 Equipment notes payable 2,318 2,680 Notes payable 13,296 14,438 8% senior notes 321,057 — 7.375% senior notes — 272,998 Subtotal 431,671 394,227 Current portion of equipment note payable (1,546 ) (1,320 ) Current portion of note payable (1,212 ) (1,145 ) Capital leases (included in other long term liabilities) (772 ) (1,360 ) Total $ 428,141 $ 390,402 Credit agreement On December 30, 2016, the Company, Great Lakes Dredge & Dock Company, LLC, NASDI Holdings, LLC, Great Lakes Dredge & Dock Environmental, Inc., Great Lakes Environmental & Infrastructure Solutions, LLC and Great Lakes Environmental & Infrastructure, LLC (collectively, the “Credit Parties”) entered into a revolving credit and security agreement, as subsequently amended, (the “Credit Agreement”) with certain financial institutions from time to time party thereto as lenders, PNC Bank, National Association, as Agent, PNC Capital Markets, The PrivateBank and Trust Company, Suntrust Robinson Humphrey, Inc., Capital One, National Association and Bank of America, N.A., as Joint Lead Arrangers and Joint Bookrunners, Texas Capital Bank, National Association, as Syndication Agent and Woodforest National Bank, as Documentation Agent. The Credit Agreement, which replaced the Company’s former revolving credit agreement, provides for a senior secured revolving credit facility in an aggregate principal amount of up to $250,000, subfacilities for the issuance of standby letters of credit up to a $250,000 sublimit and swingline loans up to a $25,000 sublimit. The maximum borrowing capacity under the Credit Agreement is determined by a formula and may fluctuate depending on the value of the collateral included in such formula at the time of determination. The Credit Agreement also includes an increase option that will allow the Company to increase the senior secured revolving credit facility by an aggregate principal amount of up to $100,000. This increase is subject to lenders providing incremental commitments for such increase, the Credit Parties having adequate borrowing capacity and provided that no default or event of default exists both before and after giving effect to such incremental commitment increase. On December 6, 2017, the Company and the Credit Parties entered into a Consent and Amendment No. 3 (the “Credit Amendment”) to the Credit Agreement with the Agent, and the other required lenders thereunder. The Credit Amendment was entered into to, among other things, obtain consent from the required lenders under the Credit Agreement to permit the Company to consummate certain asset sales, retirements and other restructuring activities described therein, as part of the Company’s plan to reduce overhead, retire certain underperforming and underutilized assets and close out the Company’s Brazilian operations (see Note 13, Restructuring Charges). This consent is subject to a number of important conditions, qualifications, limitations and exceptions that are described in the Credit Amendment. The Credit Amendment also amends the Credit Agreement to provide that (i) with respect to the Company’s 2017 and 2018 fiscal years, upon written election from the Company to Agent, including supporting documentation in form and substance satisfactory to Agent, up to an aggregate of $20,000 of expenses related to the buy-out of operating leases shall not constitute capital expenditures under the Credit Agreement; and (ii) if the amount of capital expenditures incurred by all Credit Parties in fiscal year 2017 does not exceed $75,000 then any amount remaining may be carried forward to be incurred in fiscal year 2018; provided further that, the aggregate amount of all capital expenditures incurred by all Credit Parties in fiscal years 2017 and 2018 does not exceed $135,000. Additionally, the Credit Amendment contains acknowledgments and agreements from the Agent and the required lenders with respect to certain EBITDA add-backs for fiscal years 2017 and 2018 described therein. The Credit Agreement contains customary representations and affirmative and negative covenants, including a springing financial covenant that requires the Credit Parties to maintain a fixed charge coverage ratio (ratio of earnings before income taxes, depreciation and amortization, net interest expenses, non-cash charges and losses and certain other non-recurring charges, minus capital expenditures, income and franchise taxes, to net cash interest expense plus scheduled cash principal payments with respect to debt plus restricted payments paid in cash) of not more than 1.10 to 1.00. The Company is required to maintain this ratio if its availability under the Credit Agreement falls below $31,250 for five consecutive days or $25,000 for one day. The Credit Parties are also restricted in the amount of capital expenditures they may make in each of the next three fiscal years. The Credit Agreement also contains customary events of default (including non-payment of principal or interest on any material debt and breaches of covenants) as well as events of default relating to certain actions by the Company’s surety bonding providers. The obligations of the Credit Parties under the Credit Agreement will be unconditionally guaranteed, on a joint and several basis, by each existing and subsequently acquired or formed material direct and indirect domestic subsidiary of the Company. Borrowings under the Credit Agreement have been or will be used to refinance existing indebtedness under the Company’s former revolving credit agreement, refinance existing indebtedness under the Company’s former term loan agreement, pay fees and expenses related to the Credit Agreement, finance acquisitions permitted under the Credit Agreement, finance ongoing working capital and for other general corporate purposes. The Credit Agreement matures on December 30, 2019. The obligations under the Credit Agreement are secured by substantially all of the assets of the Credit Parties. The outstanding obligations thereunder shall be secured by a valid first priority perfected lien on substantially all of the vessels of the Credit Parties and a valid perfected lien on all domestic accounts receivable and substantially all other assets of the Credit Parties, subject to the permitted liens and interests of other parties (including the Company’s surety bonding provider). Interest on the senior secured revolving credit facility of the Credit Agreement is equal to either a Base Rate option or LIBOR option, at the Company’s election. The Base Rate option is (1) the base commercial lending rate of PNC Bank, National Association, as publically announced plus (2)(a) an interest margin of 2.0% or (b) after the date on which a borrowing base certificate is required to be delivered under Section 9.2 of the Credit Agreement (commencing with the fiscal quarter ending December 31, 2017, the “Adjustment Date”), an interest margin ranging between 1.5% and 2.0% depending on the quarterly average undrawn availability on the senior secured revolving credit facility. The LIBOR option is the sum of (1) LIBOR and (2) (a) an interest margin of 3.0% or (b) after the Adjustment Date, an interest rate margin ranging between 2.5% to 3.0% per annum depending on the quarterly average undrawn availability on the senior secured revolving credit facility. The Credit Agreement is subject to an unused fee ranging from 0.25% to 0.375% per annum depending on the amount of average daily outstandings under the senior secured revolving credit facility. As of December 31, 2017, the Company had $95,000 of borrowings on the revolver and $34,290 of letters of credit outstanding, resulting in $76,819 of availability under the Credit Agreement. Prior revolving credit agreement and term loan facility In conjunction with the Credit Agreement entered into on December 30, 2016, the senior revolving credit agreement with an aggregate principal amount of up to $199,000 and the senior secured term loan facility consisting of a term loan in an aggregate principal amount of $50,000 was paid in full. Depending on the Company’s consolidated leverage ratio, previous borrowings under the revolving credit facility bore 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. The previous borrowings under the Term Loan Facility bore interest at a fixed rate of 4.655% per annum. Senior notes The Company has outstanding $325,000 of 8.000% senior notes (“8% Senior Notes”) due May 15, 2022. The 8% Senior Notes were issued at 100% of face value resulting in net proceeds of $321,653, net of underwriting fees. In connection with the issuance of the 8% Senior Notes, the Company retired all of its $275,000 of 7.375% senior notes due February 2019 for $282,638, which included a tender premium and accrued and unpaid interest. The Company used the remaining net proceeds from the debt offering to reduce the Company’s indebtedness under its Credit Agreement. Other The Company enters into note arrangements to finance certain vessels and ancillary equipment. During the first quarter of 2015, the Company financed the $15,569 acquisition of a vessel previously under an operating lease with a note bearing interest at 5.75% to maturity in 2023. The scheduled principal payments through the maturity date of the Company’s long-term debt, excluding equipment notes and capital leases, at December 31, 2017, are as follows: Years Ending December 31, 2018 $ 1,212 2019 96,502 2020 1,816 2021 1,922 2022 327,035 Thereafter 4,843 Total $ 433,330 The Company incurred amortization of deferred financing fees for its long term debt of $3,280, $2,438 and $1,729 for each of the years ended December 31, 2017, 2016 and 2015. Such amortization is recorded as a component of interest expense.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	9. 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 times, the Company holds certain derivative contracts that it uses to manage foreign currency risk or 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 December 31, 2017 Quoted Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable (Level 3) Fuel hedge contracts $ 2,501 $ — $ 2,501 $ — Fair Value Measurements at Reporting Date Using Description At December 31, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fuel hedge contracts $ 2,293 $ — $ 2,293 $ — Foreign exchange contracts The Company has various exposures to foreign currencies that fluctuate in relation to the U.S. dollar. The Company periodically enters into foreign exchange forward contracts to hedge this risk. At December 31, 2017 and 2016 there were no outstanding contracts. 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 eligible fuel requirements for work in domestic backlog. As of December 31, 2017, 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 December 2018. As of December 31, 2017, there were 9.8 million gallons remaining on these contracts which represent approximately 80% of the Company’s forecasted domestic fuel purchases through December 2018. Under these swap agreements, the Company will pay fixed prices ranging from $1.53 to $2.02 per gallon. At December 31, 2017 and December 31, 2016, the fair value asset of the fuel hedge contracts was estimated to be $2,501 and $2,293, respectively, and is recorded in other current assets. For fuel hedge contracts considered to be highly effective, the losses reclassified to earnings from changes in fair value of derivatives, net of cash settlements and taxes, for the year ended December 31, 2017 were $218. The remaining gains and losses included in the accumulated other comprehensive income (loss) at December 31, 2017 will be reclassified into earnings over the next twelve months, corresponding to the period during which the hedged fuel is expected to be utilized. Changes in the fair value of fuel hedge contracts not considered highly effective are recorded as cost of contract revenues in the Statement of Operations. The fair value of fuel hedges are corroborated using inputs that are readily observable in public markets; therefore, the Company determines fair values of these fuel hedges using Level 2 inputs. The Company is exposed to counterparty credit risk associated with non-performance of its various derivative instruments. The Company’s risk would be limited to any unrealized gains on current positions. To help mitigate this risk, the Company transacts only with counterparties that are rated as investment grade or higher. In addition, all counterparties are monitored on a continuous basis. The fair value of the fuel hedge contracts outstanding as of December 31, 2017 and 2016 is as follows: Balance Sheet Location Fair Value at December 31, 2017 2016 Asset derivatives: Derivatives designated as hedging instruments Fuel hedge contracts Other current assets 2,501 546 Derivatives not designated as hedging instruments Fuel hedge contracts Other current assets 1,747 Total asset derivatives $ 2,501 $ 2,293 Assets and liabilities measured at fair value on a nonrecurring basis All other nonfinancial assets and liabilities measured at fair value in the financial statements on a nonrecurring basis are subject to fair value measurements and disclosures. Nonfinancial assets and liabilities included in our consolidated balance sheets and measured on a nonrecurring basis consist of goodwill and long-lived assets, including other acquired intangibles. Assets included within assets held for sale are reclassified from property and equipment at fair value less cost to sell. Goodwill and long-lived assets are measured at fair value to test for and measure impairment, if any, at least annually for goodwill or when necessary for both goodwill and long-lived assets. In 2015, the Company estimated the fair value of our Terra Contracting Services, LLC, which was one of the Company’s reporting units at the time, for our goodwill impairment test by using both a market-based approach and an income-based approach. The income approach is dependent on a number of factors, including estimates of future market growth trends, forecasted revenues and expenses based upon historical operating data, appropriate discount rates and other variables. The market approach measures the value of a reporting unit through comparison to comparable companies. Under the market approach, the Company uses the guideline public company method by applying estimated market-based enterprise value multiples to the reporting unit’s estimated revenue and Adjusted EBITDA from continuing operations. The Company analyzed companies that performed similar services or are considered peers. An impairment of goodwill was recorded in the amount of $2,750 in the second quarter of 2015. The fair value of goodwill was determined using quantitative models that contained significant unobservable inputs and accordingly is a Level 3 fair value measurement. See Note 6. Fair Goodwill Balance at January 1, $ 86,326 Impairment of goodwill (2,750 ) Balance at December 31, 2015 $ 83,576 Accumulated other comprehensive income (loss) Changes in the components of the accumulated balances of other comprehensive income (loss) are as follows: 2017 2016 2015 Cumulative translation adjustments—net of tax $ (41 ) $ 508 $ (1,249 ) Derivatives: Reclassification of derivative (gains) losses to earnings—net of tax (218 ) 30 — Change in fair value of derivatives—net of tax 1,407 300 — Net unrealized (gain) loss on derivatives—net of tax 1,189 330 — Total other comprehensive income (loss) $ 1,148 $ 838 $ (1,249 ) Adjustments reclassified from accumulated balances of other comprehensive income (loss) to earnings are as follows: Statement of Operations Location 2017 2016 Derivatives: Fuel hedge contracts Costs of contract revenues $ (358 ) $ 50 Income tax benefit 140 20 $ (218 ) $ 30 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. Based on timing of the cash flows and comparison to current market interest rates, the carrying value of our senior revolving credit agreement approximates fair value. In May 2017, the Company issued a total of $325,000 of 8.000% senior notes due May 15, 2022, which were outstanding at December 31, 2017 (See Note 8, Long-Term Debt). 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 $340,048 at December 31, 2017, which is a Level 1 fair value measurement as the senior notes value was obtained using quoted prices in active markets. It is impracticable to determine the fair value of outstanding letters of credit or performance, bid and payment bonds due to uncertainties as to the amount and timing of future obligations, if any.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	10. The Company’s income tax benefit from continuing and discontinued operations for the year ended December 31, 2017 is as follows: 2017 Income tax benefit from continuing operations $ 35,610 Income tax benefit from discontinued operations 8,203 Income tax benefit $ 43,813 The Company’s loss from continuing operations before income tax from domestic and foreign continuing operations for the years ended December 31, 2017, 2016 and 2015 is as follows: 2017 2016 2015 Domestic operations $ (17,307 ) $ (2,295 ) $ (35,996 ) Foreign operations (36,866 ) (11,674 ) 27,310 Total loss from continuing operations before income tax $ (54,173 ) $ (13,969 ) $ (8,686 ) The benefit for income taxes from continuing operations as of December 31, 2017, 2016 and 2015 is as follows: 2017 2016 2015 Federal: Current $ (248 ) 260 $ — Deferred (33,592 ) (5,098 ) (2,355 ) State: Current 29 54 115 Deferred (1,812 ) (1,153 ) (673 ) Foreign: Current 13 146 416 Deferred — — — Total $ (35,610 ) $ (5,791 ) $ (2,497 ) The Company’s income tax benefit from continuing operations reconciles to the provision at the statutory U.S. federal income tax rate of 35% for the years ended December 31, 2017, 2016 and 2015 as follows: 2017 2016 2015 Tax benefit at statutory U.S. federal income tax rate $ (18,958 ) $ (4,889 ) $ (3,040 ) State income tax — net of federal income tax benefit (2,488 ) (1,118 ) (676 ) Impact of Tax Cuts and Job Act (15,720 ) — — Charitable contributions — — (469 ) Adjustment to deferred tax depreciation — — 1,135 Change in deferred state tax rate — (1,082 ) — Research and development tax credits (170 ) (253 ) (286 ) Purchase price adjustment — — 393 Changes in unrecognized tax benefits 10 10 (186 ) Changes in valuation allowance 1,152 1,031 270 Other 564 510 362 Income tax benefit $ (35,610 ) $ (5,791 ) $ (2,497 ) On December 22, 2017, the U.S. government enacted comprehensive tax legislation referred to as the Tax Act. The Tax Act makes broad and complex changes to the U.S. tax code, including but not limited to (1) reducing the U.S. federal corporate tax rate from 35% to 21%; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) requiring a current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations; (5) eliminating the corporate alternative minimum tax (AMT); (6) creating the base erosion anti-abuse tax (BEAT), a new minimum tax; (7) creating a new limitation on deductible interest expense; and (8) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017. The Company completed its calculation of the income tax effect of the Tax Act for the year ended December 31, 2017. As the Company is in a net deferred tax liability position as of the date of enactment of the Tax Act, the impact to the Company is a deferred income tax benefit of $15,720, primarily as a result of the reduction in the U.S. federal income tax rate. The other changes in tax law do not materially impact the Company for the year. At December 31, 2017 and 2016, the Company had loss carryforwards for federal income tax purposes of $207,875 and $51,158 respectively, which expire between 2034 and 2037. At December 31, 2017 and 2016, the Company had gross net operating loss carryforwards for state income tax purposes totaling $209,877 and $128,066, respectively, which expire between 2023 and 2037. Due to changes in state tax law enacted during the year in a certain state, a valuation allowance in the amount of $767 was established in 2016 for state net operating loss carryforwards. In 2017, the valuation allowance was increased by $1,152. The Company also has foreign gross net operating loss carryforwards of approximately $7,637 and $12,165 as of December 31, 2017 and 2016, of which $2,898 expires between 2018 and 2028. The remaining amount of $4,739 may be carried forward indefinitely. At December 31, 2017 and 2016, a full valuation allowance has been established for the deferred tax asset of $1,962 and $3,795 related to foreign net operating loss carryforwards, respectively, as the Company believes it is more likely than not that the net operating loss carryforwards will not be realized. As of December 31, 2017 and 2016, the Company had $157 in unrecognized tax benefits, the recognition of which would have an impact of $124 on the effective tax rate. The Company does not expect that total unrecognized tax benefits will significantly increase or decrease within the next 12 months. Below is a tabular reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of each period. 2017 2016 2015 Unrecognized tax benefits — January 1 $ 157 $ 157 $ 442 Gross increases — tax positions in prior period — — — Gross increases — current period tax positions — — — Gross decreases — expirations — — — Gross decreases — tax positions in prior period — — (285 ) Unrecognized tax benefits — December 31, $ 157 $ 157 $ 157 The Company’s policy is to recognize interest and penalties related to income tax matters in income tax expense. As of December 31, 2017 and 2016, the Company had approximately $53 and $37, respectively, of interest and penalties recorded. The Company files income tax returns at the U.S. federal level and in various state and foreign jurisdictions. U.S. federal income tax years prior to 2014 are closed and no longer subject to examination. In 2016, the Internal Revenue Service completed an examination of the Company’s 2011 and 2012 U.S. federal income tax returns. The examinations did not result in any material adjustments. With few exceptions, the statute of limitations in state taxing jurisdictions in which the Company operates has expired for all years prior to 2013. In foreign jurisdictions in which the Company operates, years prior to 2012 are closed and are no longer subject to examination. The Company’s deferred tax assets (liabilities) at December 31, 2017 and 2016 are as follows: 2017 2016 Deferred tax assets: Accrued liabilities $ 8,119 $ 16,194 Federal NOLs 43,654 17,905 Foreign NOLs 1,962 3,795 State NOLs 12,382 5,989 Tax credit carryforwards 1,941 5,970 Charitable contribution 1,340 1,883 Valuation allowance (4,294 ) (7,133 ) Total deferred tax assets 65,104 44,603 Deferred tax liabilities: Depreciation and amortization (89,966 ) (111,793 ) Other liabilities (699 ) (1,259 ) Total deferred tax liabilities (90,665 ) (113,052 ) Net noncurrent deferred tax liabilities $ (25,561 ) $ (68,449 ) Deferred tax assets relate primarily to reserves and other liabilities for costs and expenses not currently deductible for tax purposes as well as net operating loss and other carryforwards. Deferred tax liabilities relate primarily to the cumulative difference between book depreciation and amounts deducted for tax purposes. The Company evaluates its ability to realize deferred tax assets by considering all available positive and negative evidence. This evidence includes the Company’s cumulative earnings or losses in recent years. The Company further considers the impact on these cumulative earnings or losses of discontinued operations and other divested operations and joint ventures, restructuring charges and other nonrecurring adjustments that are not indicative of the Company’s ability to generate taxable income in future periods. The Company also considers sources of taxable income, such as the amount and timing of realization of its deferred tax liabilities relative to the timing of expiration of loss carryforwards. When it is estimated to be more likely than not that all or some portion of deferred tax assets will not be realized, the Company establishes a valuation allowance for the amount of such deferred tax assets considered to be unrealizable. After evaluating the positive and negative evidence for future realization of deferred tax assets, the Company recorded valuation allowances for foreign net operating loss carryforwards, foreign tax credits and certain state net operating loss carryforwards to reduce the balance of these deferred tax assets at December 31, 2017 and 2016 as it was more likely than not that the balance of these tax items would not be realized. By contrast, after evaluating the positive and negative evidence, the Company concluded that it was more likely than not that the deferred federal income tax asset recorded at December 31, 2017 and 2016 would ultimately be realized and determined that no valuation allowance was required.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	11. SHARE-BASED COMPENSATION The Company’s 2017 Long-Term Incentive Plan (“Incentive Plan”) permits the granting of stock options, stock appreciation rights, restricted stock and restricted stock units to its employees and directors for up to 3.3 million shares of common stock, plus an additional 1.7 million shares underlying equity awards issued under the 2007 Long-Term Incentive Plan. The Company may also issue share-based compensation as inducement awards to new employees upon approval of the Board of Directors. Compensation cost charged to expense related to share-based compensation arrangements was $2,963, $2,455 and $4,040, for the years ended December 31, 2017, 2016 and 2015, respectively. Non-qualified stock options The NQSO awards were granted with an exercise price equal to the market price of the Company’s common stock at the date of grant. The option awards generally vest in three equal annual installments commencing on the first anniversary of the grant date, and have ten year exercise periods. The fair value of the NQSOs was determined at the grant date using a Black-Scholes option pricing model, which requires the Company to make several assumptions. The risk-free interest rate is based on the U.S. Treasury yield curve in effect for the expected term of the option at the time of grant. The annual dividend yield on the Company’s common stock is based on estimates of future dividends during the expected term of the NQSOs. The expected life of the NQSOs was determined from historical exercise data providing a reasonable basis upon which to estimate the expected life. The volatility assumptions were based on historical volatility of Great Lakes. There is not an active market for options on the Company’s common stock and, as such, implied volatility for the Company’s stock was not considered. Additionally, the Company’s general policy is to issue new shares of registered common stock to satisfy stock option exercises or grants of restricted stock. No NQSO awards were granted in 2017, 2016 and 2015. A summary of stock option activity under the Incentive Plan as of December 31, 2017, and changes during the year ended December 31, 2017, is presented below: Options Shares Weighted Exercise Price Weighted-Average Remaining Contract Term (yrs) Aggregate Intrinsic Value ($000's) Outstanding as of January 1, 2017 1,699 $ 6.32 Granted — — Exercised (4 ) 3.82 Forfeited or Expired (318 ) 6.26 Outstanding as of December 31, 2017 1,377 $ 6.34 3.4 $ 195 Vested at December 31, 2017 1,377 $ 6.34 3.4 $ 195 Restricted stock units RSUs can either vest in equal portions over the three year vesting period or vest in one installment on the third anniversary of the grant date. The fair value of RSUs was based upon the Company’s stock price on the date of grant. A summary of the status of the Company’s non-vested RSUs as of December 31, 2017, and changes during the year ended December 31, 2017, is presented below: Nonvested Restricted Stock Units Shares Weighted-Average Grant-Date Fair Value Outstanding as of January 1, 2017 2,532 $ 5.23 Granted 1,018 4.42 Vested (222 ) 5.66 Forfeited (1,132 ) 5.72 Outstanding as of December 31, 2017 2,196 $ 5.06 Expected to vest at December 31, 2017 1,430 $ 4.60 As of December 31, 2017, there was $3,171 of total unrecognized compensation cost related to non-vested RSUs granted under the Plan. That cost for non-vested RSUs is expected to be recognized over a weighted-average period of 1.9 years. The Incentive Plan permits the employee to use vested shares from RSUs to satisfy the grantee’s U.S. federal income tax liability resulting from the issuance of the shares through the Company’s retention of that number of common shares having a market value as of the vesting date equal to such tax obligation up to the minimum statutory withholding requirements. The amount related to shares used for such tax withholding obligations was approximately $328 and $171 for the years ended December 31, 2017 and 2016, respectively. Director compensation The Company uses a combination of cash and share-based compensation to attract and retain qualified candidates to serve on our Board of Directors. Compensation is paid to non-employee directors. Directors who are employees receive no additional compensation for services as members of the Board or any of its committees. Share-based compensation is paid pursuant to the Incentive Plan. Each non-employee director of the Company receives an annual retainer of $155, payable quarterly in arrears, and is generally paid 50% in cash and 50% in common stock of the Company. Directors may elect to receive some or all of the cash retainer in common stock. In 2017, the Chairman of the Board received an additional $150 of annual compensation, paid 100% in common stock. In the years ended December 31, 2017, 2016 and 2015, 207 thousand, 86 thousand and 112 thousand shares, respectively, of the Company’s common stock were issued to non-employee directors under the Incentive Plan.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Retirement Plans	12. RETIREMENT PLANS The Company sponsors four 401(k) savings plans, one covering substantially all non-union salaried employees (“Salaried Plan”), a second covering its hourly employees (“Hourly Plan”), a third plan specifically for its employees that are members of a tugboat union and a fourth for the salary and non-union employees of certain subsidiaries (“Affiliated Plan”). Under the Salaried Plan, the Hourly Plan and the Affiliated Plan, individual employees may contribute a percentage of compensation and the Company will match a portion of the employees’ contributions. The Salaried Plan and Affiliated Plan also include a discretionary profit-sharing component, permitting the Company to make discretionary employer contributions to all eligible employees of these plans. Additionally, the Company sponsors a Supplemental Savings Plan in which the Company makes contributions for certain key executives. The Company’s expense for matching, discretionary and Supplemental Savings Plan contributions for 2017, 2016 and 2015, was $6,236, $3,705 and $6,772, respectively. The Company also contributes to various multiemployer pension plans pursuant to collective bargaining agreements. In 2017, 2016 and 2015, the Company contributed $5,639, $6,298 and $4,990 respectively to all of the multiemployer plans that provide pension benefits in our continuing operations. The information available to the Company about the multiemployer plans in which it participates, whether via request to the plan or publicly available, is generally dated due to the nature of the reporting cycle of multiemployer plans and legal requirements under the Employee Retirement Income Security Act (“ERISA”) as amended by the Multiemployer Pension Plan Amendments Act (“MPPAA”). Based upon these plans’ most recently available annual reports, the Company’s contributions to these plans were less than 5% of each plan’s total contributions for all but one plan. Information on significant multiemployer pension plans in which the Company participates is included in the table below: Pension Protection Act of 2006 Certified Zone Status at December 31, Company's Contributions Pension Plan Legal Name Federal Identification Number 2017 2016 Expiration of Collective Bargaining Arrangement with the Company 2017 2016 2015 Seafarers Pension Trust 13-6100329 001 Green Green February 28, 2018 $ 1,182 $ 1,102 $ 1,005 The Company does not expect any future increased contributions to have a material negative impact on its financial position, results of operations or cash flows for future years. The risks of participating in multiemployer plans are different from single employer plans as assets contributed are available to provide benefits to employees of other employers and unfunded obligations from an employer that discontinues contributions are the responsibility of all remaining employers. In addition, in the event of a plan’s termination or the Company’s withdrawal from a plan, the Company may be liable for a portion of the plan’s unfunded vested benefits. However, information from the plans’ administrators is not available to permit the Company to determine its share, if any, of unfunded vested benefits.

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Restructuring Charges	13. RESTRUCTURING CHARGES In 2017, a strategic review was begun to improve the Company's financial results in both domestic and international operations enabling debt reduction, improvements in return on capital and the continued renewal of our extensive fleet with new and efficient dredges to best serve our domestic and international clients. As a result of this review, management began execution of a plan to reduce general and administrative and overhead expenses, retire certain underperforming and underutilized assets, write-off pre-contract costs on a project that was never formally awarded and that the Company no longer intends to pursue and closeout the Company’s Brazil operations. These changes will result in a restructuring charge of approximately $42,000-$47,000, including severance of approximately $3,000, asset retirements of approximately $30,000-$34,000, pre-contract costs of approximately $6,500 and closeout costs of approximately $2,500-$3,500. Approximately $38,000-$43,000 of this charge will be non-cash and includes depreciation, loss on sale of assets and other items, approximating totals of $12,500-$14,500, $3,000-$5,000 and $21,500-$23,500, respectively. The majority of the charge was recorded in the second half of 2017 with the remainder to be recognized in the dredging segment in the following year. Restructuring charges currently recognized for the above actions are summarized as follows: Twelve Months Ended December 31, 2017 Costs of contract revenues - depreciation $ 6,859 Costs of contract revenues - other 16,102 General and administrative expenses 1,189 Loss on sale of assets—net 4,691 Total Dredging 28,841 Costs of contract revenues - depreciation — Costs of contract revenues - other 7 General and administrative expenses 637 Total Environmental & Infrastructure 644 Costs of contract revenues - depreciation 6,859 Costs of contract revenues - other 16,109 General and administrative expenses 1,826 Loss on sale of assets—net 4,691 Total Consolidated 29,485 The Company accrued rent expense of $5,930 and severance expense of $1,567 at December 31, 2017. Both of these items are included in accrued expenses at December 31, 2017 and are expected to be settled in 2018.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments And Contingencies	14. COMMITMENTS AND CONTINGENCIES Commercial commitments Performance and bid bonds are customarily required for dredging and marine construction projects, as well as some environmental & infrastructure projects. The Company has bonding agreements with Argonaut Insurance Company, Berkley Insurance Company, Chubb Surety and Liberty Mutual Insurance Company In connection with the sale of our historical demolition business, the Company was obligated to keep in place the surety bonds on pending demolition projects for the period required under the respective contract for a project and issued Zurich a letter of credit related to this exposure. In February 2017, the Company was notified by Zurich of an alleged default triggered on a historical demolition surety performance bond in the aggregate of approximately $20,000 for failure of the contractor to perform in accordance with the terms of a project. In May 2017, Zurich drew upon the letter of credit in the amount of $20,881. In order to fund the draw on the letter of credit, the Company had to increase the borrowings on its revolving credit facility. As the outstanding letters of credit previously reduced the Company’s availability under the revolving credit facility, the draw down on the Company’s letter of credit does not impact its liquidity or capital availability. Pursuant to the terms of sale of our historical demolition business, the Company received an indemnification from the buyer for losses resulting from the bonding arrangement. The Company intends to aggressively pursue enforcement of the indemnification provisions if the buyer of the historical demolition business is found to be in default of its obligations. The Company cannot estimate the amount or range of recoveries related to the indemnification or resolution of the Company’s responsibilities under the surety bond. The surety bond claim impact has been included in discontinued operations and is discussed in Note 17, Business Combinations and Dispositions. 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 results of operations, cash flows or financial condition. On April 23, 2014, the Company completed the sale of NASDI, LLC (“NASDI”) and Yankee Environmental Services, LLC (“Yankee”), which together comprised the Company’s historical demolition business, to a privately owned demolition company. Under the terms of the divestiture, the Company retained certain pre-closing liabilities relating to the disposed business. Certain of these liabilities and a legal action brought by the Company to enforce the buyer’s obligations under the sale agreement are described below. On January 14, 2015, the Company and our subsidiary, NASDI Holdings, LLC, brought an action in the Delaware Court of Chancery to enforce the terms of the Company's agreement to sell NASDI and Yankee. Under the terms of the agreement, the Company received cash of $5,309 and retained the right to receive additional proceeds based upon future collections of outstanding accounts receivable and work in process existing at the date of close. The Company seeks specific performance of buyer’s obligation to collect and to remit the additional proceeds, and other related relief. Defendants have filed counterclaims alleging that the Company misrepresented the quality of its contracts and receivables prior to the sale. The Company denies defendants’ allegations and intends to vigorously defend against the counterclaims. 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. Lease obligations The Company leases certain operating equipment and office facilities under long-term operating leases expiring at various dates through 2024. The equipment leases contain renewal or purchase options that specify prices at the then fair value upon the expiration of the lease terms. The leases also contain default provisions that are triggered by an acceleration of debt maturity under the terms of the Company’s Credit Agreement, or, in certain instances, cross default to other equipment leases and certain lease arrangements require that the Company maintain certain financial ratios comparable to those required by its Credit Agreement. Additionally, the leases typically contain provisions whereby the Company indemnifies the lessors for the tax treatment attributable to such leases based on the tax rules in place at lease inception. The tax indemnifications do not have a contractual dollar limit. To date, no lessors have asserted any claims against the Company under these tax indemnification provisions. Future minimum operating lease payments at December 31, 2017, are as follows: 2018 $ 21,310 2019 17,119 2020 14,365 2021 12,500 2022 8,773 Thereafter 8,408 Total minimum operating lease payments $ 82,475 Total rent expense under long-term operating lease arrangements for the years ended December 31, 2017, 2016 and 2015 was $27,218, $21,061 and $21,697, respectively. This excludes expenses for equipment and facilities rented on a short-term, as-needed basis. For more information about charges to rent expense during 2017 related to the Company’s restructuring refer to Note 13, Restructuring Charges.

Investments

Investments	12 Months Ended
	Dec. 31, 2017
Equity Method Investments And Joint Ventures [Abstract]
Investments	15. INVESTMENTS Amboy Aggregates The Company and a New Jersey aggregates company each owned 50% of Amboy Aggregates (“Amboy”). Amboy was formed in December 1984 to mine sand from the entrance channel to New York Harbor to provide sand and aggregate for use in road and building construction and for clean land fill. Amboy sold its interest in a stone import business and its holdings in land during 2014. Amboy was dissolved in 2017. The Company accounts for this investment under the equity method. The following is summarized financial information for this dissolved entity: 2017 2016 2015 Revenue $ — $ — $ 139 Gross profit (loss) — 758 (1,363 ) Income (loss) from continuing operations 34 758 (3,152 ) Net income (loss) 34 758 (3,152 ) TerraSea Environmental Solutions The Company owned 50% of TerraSea Environmental Solutions (“TerraSea”) as a joint venture. TerraSea was engaged in the environmental services business through its ability to remediate contaminated soil and dredged sediment treatment. At December 31, 2016, the Company had net advances to TerraSea of $24,696, which are recorded in other current assets. The Company had an accumulated deficit in joint ventures, which represents losses recognized to date in excess of our investment in TerraSea, of $17,016 at December 31, 2016, which is presented in accrued expenses. During the second quarter of 2017, the Company and the joint venture partner agreed to a final resolution of the net advances through additional funding of the joint venture. The Company recorded additional losses of $1,458 related to this joint venture during the year ended December 31, 2017. TerraSea was dissolved in 2017. The Company accounts for this investment under the equity method. The following is summarized financial information for this dissolved entity: 2016 2015 Revenue $ — $ 6,960 Gross loss (183 ) (3,800 ) Net loss (183 ) (3,800 )

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	16. RELATED-PARTY TRANSACTIONS The Company’s Environmental & Infrastructure Segment operated out of two facilities owned by the former owner of Terra Contracting, LLC until November 11, 2016, when the lease was terminated. The Company paid $195 and $243 on rent on these properties in 2016 and 2015, respectively. Further, the Company’s Environmental & Infrastructure Segment operated out of two facilities owned by Magnus Real Estate Group, LLC, which was owned by the former owners of Magnus Pacific Corporation (“Magnus”). In 2017, 2016 and 2015, the Company paid rent of $263, $506 and $402, respectively, for these two properties. In March 2017, one of the properties was sold to a non-related party.

Business Combinations And Dispo

Business Combinations And Dispositions	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combinations And Dispositions	17. BUSINESS COMBINATIONS AND DISPOSITIONS Discontinued operations On April 23, 2014, the Company entered into an agreement and completed the sale of NASDI, LLC and Yankee Environmental Services, LLC, its two former subsidiaries that comprised the historical demolition business. Under the terms of the agreement, the Company received cash of $5,309 and retained the right to receive additional proceeds based upon future collections of outstanding accounts receivable and work in process existing at the date of close, including recovery of outstanding claims for additional compensation from customers, and net of future payments of accounts payable existing at the date of close, including any future payments of obligations associated with outstanding claims. The amount and timing of the working capital settlement and the amount and timing of the realization of additional net proceeds may be impacted by the litigation with the buyer of the historical demolition business (see Note 14, Commitment and Contingencies). However, management believes that the ultimate resolution of these matters will not be material to the Company’s consolidated financial position or results of operations. As discussed in Note 14, the Company was notified by Zurich of an alleged default triggered on a historical demolition surety performance bond in the aggregate of approximately $20,000 for failure of the contractor to perform in accordance with the terms of a project. Zurich could be obligated to reimburse the loss, damage and expense that may arise from the alleged default. The Company estimated its exposure to a surety bond claim, including associated expense to be $20,900 and has recorded this amount in discontinued operations for the year ended December 31, 2017 as follow: 2017 Revenue $ — Loss before income taxes from discontinued operations $ (20,900 ) Income tax benefit 8,203 Loss from discontinued operations, net of income taxes $ (12,697 ) Magnus Pacific acquisition On November 4, 2014, the Company acquired Magnus, a California corporation, for an aggregate purchase price of approximately $40 million. Under the terms of the acquisition, the aggregate purchase price is satisfied by payment of $25,000 paid at closing, the issuance of a promissory note and an earnout payment. Magnus did not reach the minimum EBITDA threshold for 2015 designated in the secured promissory note; therefore, during 2015, the Company reduced the remaining fair value to zero. Under the terms of the acquisition, as amended, the maximum potential aggregate earnout (the “Earnout Payment”) is $11,400 and will be determined based on the attainment of an average Adjusted EBITDA target of Magnus, now referred to as Great Lakes E&I, for the years ending December 31, 2017, December 31, 2018 and December 31, 2019. The Earnout Payment may be paid in cash or shares of the Company’s common stock, at the Company’s option. The Company remeasures the fair value of the contingent Earnout Payment based on projections of the earnings target for the business. Based on the Company’s current projections, Great Lakes E&I is not expected to reach the minimum Adjusted EBITDA threshold designated in the amended share purchase agreement. Accordingly, during the third quarter of 2016, the Company reduced the remaining fair value of $8,940 to zero and the corresponding change was reflected in general and administrative expenses and interest expense. Other During the fourth quarter of 2016, the Company sold assets associated with certain service lines of the environmental & infrastructure segment’s business, excluding assets supporting the remediation service line. In connection with the sale, the Company recorded a $2,758 loss to (gain) loss on sale of assets—net for the year ended December 31, 2016.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	18. SEGMENT INFORMATION The Company and its subsidiaries currently operate in two reportable segments: dredging and environmental & infrastructure. 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 2017, 2016 and 2015, is provided as follows: 2017 2016 2015 Dredging: Contract revenues $ 592,159 $ 637,468 $ 681,255 Operating income (loss) (13,353 ) 34,108 64,073 Depreciation and amortization 55,962 54,826 50,556 Total assets 878,458 912,880 872,297 Property and equipment—net 396,925 399,479 397,468 Goodwill 76,576 76,576 76,576 Investment in joint ventures — 381 1 Capital expenditures 63,912 84,263 82,000 Environmental & infrastructure: Contract revenues 112,607 133,637 181,710 Operating loss (10,172 ) (19,428 ) (41,114 ) Depreciation and amortization 4,558 8,197 14,029 Total assets 78,806 81,166 127,907 Property and equipment—net 10,369 13,529 32,742 Goodwill 7,000 7,000 7,000 Investment in joint ventures 2,714 4,353 3,760 Capital expenditures 2,156 949 7,279 Intersegment: Contract revenues (2,263 ) (3,520 ) (6,087 ) Total assets (124,907 ) (100,458 ) (102,080 ) Total: Contract revenues 702,503 767,585 856,878 Operating income (loss) (23,525 ) 14,680 22,959 Depreciation and amortization 60,520 63,023 64,585 Total assets 832,357 893,588 898,124 Property and equipment—net 407,294 413,008 430,210 Goodwill 83,576 83,576 83,576 Investment in joint ventures 2,714 4,734 3,761 Capital expenditures 66,068 85,212 89,279 The Company classifies the revenue related to its dredging projects into the following types of work: 2017 2016 2015 Capital dredging — U.S. $ 185,113 $ 219,914 $ 207,058 Capital dredging — foreign 42,306 59,413 139,945 Coastal protection dredging 191,070 215,041 184,060 Maintenance dredging 134,923 92,274 120,055 Rivers & lakes 38,747 50,826 30,137 Total dredging $ 592,159 $ 637,468 $ 681,255 The Company derived revenues and gross profit from foreign project operations for the years ended December 31, 2017, 2016, and 2015, as follows: 2017 2016 2015 Contract revenues $ 42,306 $ 59,413 $ 139,945 Costs of contract revenues (73,958 ) (66,729 ) (105,951 ) Gross profit $ (31,652 ) $ (7,316 ) $ 33,994 In 2017, 2016 and 2015, foreign revenues were primarily from work done in the Middle East. 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. As of December 31, 2017 and 2016, long-lived assets with a net book value of $47,563 and $63,729, respectively, were located outside of the U.S. The Company’s primary customer is the U.S. Army Corps of Engineers (the “Corps”), which has responsibility for federally funded projects related to waterway navigation and flood control. In 2017, 2016 and 2015, 53.6%, 53.4% and 51.0%, respectively, of contract revenues were earned from contracts with federal government agencies, including the Corps, as well as other federal entities such as the U.S. Coast Guard and U.S. Navy. At December 31, 2017 and 2016, approximately 34.7% and 39.9%, respectively, of accounts receivable, including contract revenues in excess of billings and retainage, were due on contracts with federal government agencies. The Company depends on its ability to continue to obtain federal government contracts, and indirectly, on the amount of federal funding for new and current government dredging projects. Therefore, the Company’s operations can be influenced by the level and timing of federal funding. The Company recognized an overall loss on a remediation project of $5,934 which if applied to the initial year of the contract would have decreased gross profit by nearly the entire amount of the loss in the year ended December 31, 2016. The Company recognized an overall loss on a remediation project of $7,260 which if applied to the initial year of the contract would have decreased gross profit by nearly the entire amount of the loss in the year ended December 31, 2015. The Company recognized a loss on a landfill project of $7,446 on which the change in estimate to the gross profit percentage in the year resulted in a cumulative net impact on the project margin, which decreased gross profit by extensively the entire amount of the loss in the year ended December 31, 2015. The project was completed in 2016. Revenue from foreign projects has been concentrated in the Middle East which comprised less than 10% in 2017 and 2016 and 14.7% of total revenue in 2015. At December 31, 2017 and 2016, less than 10% and approximately 13.0%, respectively, of total accounts receivable, including retainage and contract revenues in excess of billings, were due on contracts in the Middle East. There is a dependence on future projects in the Middle East, as vessels are currently located there. However, some of the vessels located in Middle East can be moved back to the U.S. or all can be moved to other international markets as opportunities arise.

Subsidiary Guarantors

Subsidiary Guarantors	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Subsidiary Guarantors	19. SUBSIDIARY GUARANTORS The Company’s long-term debt at December 31, 2017 includes $325,000 of 8.000% senior notes due May 15, 2022. The Company’s obligations under these senior unsecured notes are guaranteed by certain of the Company’s 100% owned domestic subsidiaries. Such guarantees are full, unconditional and joint and several. In connection with the 8% Senior Notes issued in May 2017, certain of the Company’s 100% owned domestic subsidiaries were released as subsidiary guarantors of the debt. Accordingly, the 2016 and 2015 financial information included below has been recast to reflect the release of these entities as subsidiary guarantors. 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 December 31, 2017 and 2016; (ii) statements of operations and comprehensive income (loss) for the years ended December 31, 2017, 2016 and 2015; and (iii) statements of cash flows for the years ended December 31, 2017, 2016 and 2015. GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2017 (In thousands) ASSETS Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated CURRENT ASSETS: Cash and cash equivalents $ 15,794 $ 38 $ 20 $ — $ 15,852 Accounts receivable — net 75,431 102 — — 75,533 Contract revenues in excess of billings 90,788 — — — 90,788 Inventories 34,600 — — — 34,600 Prepaid expenses 5,183 — — — 5,183 Other current assets 38,731 1,497 — — 40,228 Total current assets 260,527 1,637 20 — 262,184 PROPERTY AND EQUIPMENT—Net 407,293 1 — — 407,294 GOODWILL 83,576 — — — 83,576 OTHER INTANGIBLE ASSETS—Net 571 337 — — 908 INVENTORIES — Noncurrent 54,023 — — — 54,023 INVESTMENTS IN JOINT VENTURES 2,555 159 — — 2,714 ASSETS HELD FOR SALE— Noncurrent 8,530 — — — 8,530 RECEIVABLES FROM AFFILIATES 45,375 6,754 170,323 (222,452 ) — INVESTMENTS IN SUBSIDIARIES — — 511,435 (511,435 ) — OTHER 7,971 1 5,156 — 13,128 TOTAL $ 870,421 $ 8,889 $ 686,934 $ (733,887 ) $ 832,357 LIABILITIES AND EQUITY CURRENT LIABILITIES: Accounts payable $ 87,379 $ 280 $ — $ — $ 87,659 Accrued expenses 50,382 1,312 4,524 — 56,218 Billings in excess of contract revenues 3,615 — — — 3,615 Current portion of long-term debt 1,546 — 1,212 — 2,758 Total current liabilities 142,922 1,592 5,736 — 150,250 LONG-TERM DEBT — — 333,141 — 333,141 REVOLVING CREDIT FACILITY — — 95,000 — 95,000 DEFERRED INCOME TAXES — — 25,561 — 25,561 PAYABLES TO AFFILIATES 161,979 54,442 6,031 (222,452 ) — INVESTMENTS IN SUBSIDIARIES 41,358 — — (41,358 ) — OTHER 6,940 — 169 — 7,109 Total liabilities 353,199 56,034 465,638 (263,810 ) 611,061 TOTAL EQUITY 517,222 (47,145 ) 221,296 (470,077 ) 221,296 TOTAL $ 870,421 $ 8,889 $ 686,934 $ (733,887 ) $ 832,357 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2016 (In thousands) ASSETS Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated CURRENT ASSETS: Cash and cash equivalents $ 10,414 $ 751 $ 2 $ — $ 11,167 Accounts receivable — net 75,412 14,242 — (1,563 ) 88,091 Contract revenues in excess of billings 91,478 3,534 — — 95,012 Inventories 37,137 — — — 37,137 Prepaid expenses 12,287 120 — — 12,407 Other current assets 60,844 2,568 — — 63,412 Total current assets 287,572 21,215 2 (1,563 ) 307,226 PROPERTY AND EQUIPMENT—Net 407,516 5,492 — — 413,008 GOODWILL 83,576 — — — 83,576 OTHER INTANGIBLE ASSETS—Net 1,067 432 — — 1,499 INVENTORIES — Noncurrent 52,602 — — — 52,602 INVESTMENTS IN JOINT VENTURES 4,685 49 — — 4,734 ASSETS HELD FOR SALE— Noncurrent 8,390 909 — — 9,299 RECEIVABLES FROM AFFILIATES 58,284 16,807 82,340 (157,431 ) — INVESTMENTS IN SUBSIDIARIES — — 636,216 (636,216 ) — OTHER 14,692 1 6,951 — 21,644 TOTAL $ 918,384 $ 44,905 $ 725,509 $ (795,210 ) $ 893,588 LIABILITIES AND EQUITY CURRENT LIABILITIES: Accounts payable $ 101,795 $ 2,879 $ 17 $ (1,506 ) $ 103,185 Accrued expenses 55,940 3,222 9,881 — 69,043 Billings in excess of contract revenues 4,699 499 — (57 ) 5,141 Current portion of long term-debt 305 1,015 1,145 — 2,465 Total current liabilities 162,739 7,615 11,043 (1,563 ) 179,834 LONG-TERM DEBT — — 286,291 — 286,291 REVOLVING CREDIT FACILITY — — 104,111 — 104,111 DEFERRED INCOME TAXES (1,833 ) — 70,282 — 68,449 PAYABLES TO AFFILIATES 80,769 70,921 5,741 (157,431 ) — INVESTMENTS IN SUBSIDIARIES 32,000 — — (32,000 ) — OTHER 5,925 937 151 — 7,013 Total liabilities 279,600 79,473 477,619 (190,994 ) 645,698 TOTAL EQUITY 638,784 (34,568 ) 247,890 (604,216 ) 247,890 TOTAL $ 918,384 $ 44,905 $ 725,509 $ (795,210 ) $ 893,588 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE LOSS FOR THE YEAR ENDED DECEMBER 31, 2017 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals Contract revenues $ 699,607 $ 5,163 $ — $ (2,267 ) $ 702,503 Costs of contract revenues (647,467 ) (7,420 ) — 2,267 (652,620 ) Gross profit 52,140 (2,257 ) — — 49,883 OPERATING EXPENSES: General and administrative expenses 67,175 1,156 — — 68,331 Loss on sale of assets—net 4,801 276 — — 5,077 Operating loss (19,836 ) (3,689 ) — — (23,525 ) Interest income (expense)—net 1,054 (966 ) (26,134 ) — (26,046 ) Equity in earnings (loss) of subsidiaries 38 — (26,973 ) 26,935 — Equity in loss of joint ventures (1,484 ) — — — (1,484 ) Loss on extinguishment of debt — — (2,330 ) — (2,330 ) Other income (expense) (1,240 ) 452 — — (788 ) Loss from continuing operations before income taxes (21,468 ) (4,203 ) (55,437 ) 26,935 (54,173 ) Income tax (provision) benefit (1,250 ) (14 ) 36,874 — 35,610 Loss from continuing operations (22,718 ) (4,217 ) (18,563 ) 26,935 (18,563 ) Loss from discontinued operations, net of income taxes (20,900 ) — (12,697 ) 20,900 (12,697 ) Net loss $ (43,618 ) $ (4,217 ) $ (31,260 ) $ 47,835 $ (31,260 ) Comprehensive loss $ (42,429 ) $ (4,258 ) $ (30,112 ) $ 46,687 $ (30,112 ) GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE YEAR ENDED DECEMBER 31, 2016 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals Contract revenues $ 726,239 $ 44,086 $ — $ (2,740 ) $ 767,585 Costs of contract revenues (622,158 ) (61,779 ) — 2,740 (681,197 ) Gross profit 104,081 (17,693 ) — — 86,388 OPERATING EXPENSES: General and administrative expenses 51,678 13,904 (49 ) — 65,533 Loss on sale of assets—net 3,040 3,135 — — 6,175 Operating income (loss) 49,363 (34,732 ) 49 — 14,680 Interest income (expense)—net 1,985 (1,497 ) (23,395 ) — (22,907 ) Equity in earnings (loss) of subsidiaries (31,488 ) — 10,313 21,175 — Equity in loss of joint ventures (2,365 ) — — — (2,365 ) Other expense (2,626 ) (751 ) — — (3,377 ) Income (loss) before income taxes 14,869 (36,980 ) (13,033 ) 21,175 (13,969 ) Income tax (provision) benefit 1,080 (144 ) 4,856 — 5,792 Net income (loss) $ 15,949 $ (37,124 ) $ (8,177 ) $ 21,175 $ (8,177 ) Comprehensive income (loss) $ 16,279 $ (36,616 ) $ (7,339 ) $ 20,337 $ (7,339 ) GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE YEAR ENDED DECEMBER 31, 2015 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Corporation Eliminations Consolidated Totals Contract revenues $ 778,337 $ 86,666 $ — $ (8,125 ) $ 856,878 Costs of contract revenues (670,973 ) (98,107 ) — 8,125 (760,955 ) Gross profit 107,364 (11,441 ) — — 95,923 OPERATING EXPENSES: General and administrative expenses 58,682 12,387 — — 71,069 Impairment of goodwill — 2,750 — — 2,750 (Gain) loss on sale of assets—net (885 ) 30 — — (855 ) Operating income 49,567 (26,608 ) — — 22,959 Interest income (expense)—net 872 (1,398 ) (23,839 ) — (24,365 ) Equity in earnings of subsidiaries 34 — 16,282 (16,316 ) — Equity in earnings (loss) of joint ventures (6,221 ) 170 — — (6,051 ) Other income (loss) (3,180 ) 1,951 — — (1,229 ) Income (loss) before income taxes 41,072 (25,885 ) (7,557 ) (16,316 ) (8,686 ) Income tax (provision) benefit 1,641 (512 ) 1,368 — 2,497 Net income (loss) $ 42,713 $ (26,397 ) $ (6,189 ) $ (16,316 ) $ (6,189 ) Comprehensive income (loss) $ 42,713 $ (27,646 ) $ (7,438 ) $ (15,067 ) $ (7,438 ) GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2017 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals OPERATING ACTIVITIES: Net cash flows provided by operating activities of continuing operations $ 64,610 $ 4,910 $ (27,102 ) $ — $ 42,418 Net cash flows used in operating activities of discontinued operations (20,900 ) — — — (20,900 ) Cash provided by (used in) operating activities 43,710 4,910 (27,102 ) — 21,518 INVESTING ACTIVITIES: Purchases of property and equipment (75,940 ) 7,711 — — (68,229 ) Proceeds from dispositions of property and equipment 8,620 1,457 — — 10,077 Changes in restricted cash 7,035 — — — 7,035 Net change in accounts with affiliates 3,732 — (88,594 ) 84,862 — Transfer to parent — (9,615 ) 81,184 (71,569 ) — Cash used in investing activities (56,553 ) (447 ) (7,410 ) 13,293 (51,117 ) FINANCING ACTIVITIES: Proceeds from issuance of debt 1,241 — 325,000 326,241 Repayments of debt (1,602 ) — (276,148 ) — (277,750 ) 7 3/8% senior notes tender premium — — (744 ) — (744 ) Deferred financing fees — — (5,022 ) — (5,022 ) Taxes paid on settlement of vested share awards — — (328 ) — (328 ) Net change in accounts with affiliates 90,153 (5,291 ) — (84,862 ) — Transfer to parent (71,569 ) — — 71,569 — Exercise of stock options and purchases from employee stock plans — — 883 — 883 Borrowings under revolving loans — — 124,925 — 124,925 Repayments of revolving loans — — (134,036 ) — (134,036 ) Cash provided by (used in) financing activities 18,223 (5,291 ) 34,530 (13,293 ) 34,169 Effect of foreign currency exchange rates on cash and cash equivalents — 115 — — 115 Net increase (decrease) in cash and cash equivalents 5,380 (713 ) 18 — 4,685 Cash and cash equivalents at beginning of period 10,414 751 2 — 11,167 Cash and cash equivalents at end of period $ 15,794 $ 38 $ 20 $ — $ 15,852 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2016 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals OPERATING ACTIVITIES: Cash provided by (used in) operating activities $ 74,409 $ (16,677 ) $ (19,062 ) $ — $ 38,670 INVESTING ACTIVITIES: Purchases of property and equipment (83,777 ) (21 ) — — (83,798 ) Proceeds from dispositions of property and equipment 10,582 7,675 — — 18,257 Changes in restricted cash (7,035 ) — — — (7,035 ) Net change in accounts with affiliates (5,100 ) — (36,172 ) 41,272 — Transfer to parent — — 23,000 (23,000 ) — Cash provided by (used in) investing activities (85,330 ) 7,654 (13,172 ) 18,272 (72,576 ) FINANCING ACTIVITIES: Repayments of debt (296 ) (1,128 ) (45,661 ) — (47,085 ) Deferred financing fees — — (6,817 ) — (6,817 ) Taxes paid on settlement of vested share awards — — (171 ) — (171 ) Net change in accounts with affiliates 32,933 8,339 — (41,272 ) — Transfer to parent (23,000 ) — — 23,000 — Exercise of stock options and purchases from employee stock plans — — 905 — 905 Excess income tax benefit from share-based compensation — — (133 ) — (133 ) Borrowings under revolving loans — — 288,611 — 288,611 Repayments of revolving loans — — (204,500 ) — (204,500 ) Cash provided by financing activities 9,637 7,211 32,234 (18,272 ) 30,810 Effect of foreign currency exchange rates on cash and cash equivalents — 79 — — 79 Net decrease in cash and cash equivalents (1,284 ) (1,733 ) — — (3,017 ) Cash and cash equivalents at beginning of period 11,698 2,484 2 — 14,184 Cash and cash equivalents at end of period $ 10,414 $ 751 $ 2 $ — $ 11,167 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2015 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Corporation Eliminations Consolidated Totals OPERATING ACTIVITIES: Cash provided by (used in) operating activities 75,489 (22,679 ) (23,688 ) — 29,122 INVESTING ACTIVITIES: Purchases of property and equipment (70,759 ) (3,696 ) — — (74,455 ) Proceeds from dispositions of property and equipment 1,102 220 — — 1,322 Net change in accounts with affiliates (32,342 ) — (12,222 ) 44,564 — Cash used in investing activities (101,999 ) (3,476 ) (12,222 ) 44,564 (73,133 ) FINANCING ACTIVITIES: Proceeds from issuance of debt — — 3,050 — 3,050 Repayments of debt (195 ) (1,006 ) (5,443 ) — (6,644 ) Deferred financing fees — — (111 ) — (111 ) Taxes paid on settlement of vested share awards — — (267 ) — (267 ) Net change in accounts with affiliates (23,491 ) 31,991 36,064 (44,564 ) — Transfer to parent 17,258 — (17,258 ) — — Exercise of stock options and purchases from employee stock plans — — 1,365 — 1,365 Excess income tax benefit from share-based compensation — — (57 ) — (57 ) Purchase of treasury stock — — (1,433 ) — (1,433 ) Borrowings under revolving loans — — 179,500 — 179,500 Repayments of revolving loans — — (159,500 ) — (159,500 ) Cash provided by (used in) financing activities (6,428 ) 30,985 35,910 (44,564 ) 15,903 Effect of foreign currency exchange rates on cash and cash equivalents — (97 ) — — (97 ) Net increase (decrease) in cash and cash equivalents (32,938 ) 4,733 — — (28,205 ) Cash and cash equivalents at beginning of period 44,636 (2,249 ) 2 — 42,389 Cash and cash equivalents at end of period $ 11,698 $ 2,484 $ 2 $ — $ 14,184

Schedule II-Valuation And Quali

Schedule II-Valuation And Qualify Accounts	12 Months Ended
	Dec. 31, 2017
Valuation And Qualifying Accounts [Abstract]
Schedule II-Valuation And Qualifying Accounts	Great Lakes Dredge & Dock Corporation Schedule II—Valuation and Qualifying Accounts For the Years Ended December 31, 2017, 2016 and 2015 (In thousands) Additions Beginning Balance Charged to costs and expenses Charged to other accounts Deductions Ending balance Description Year ended December 31, 2015 Allowances deducted from assets to which they apply: Allowances for doubtful accounts $ 578 $ 176 $ — $ — $ 754 Valuation allowance for deferred tax assets 6,579 270 (748 ) 6,101 Total $ 7,157 $ 446 $ — $ (748 ) $ 6,855 Year ended December 31, 2016 Allowances deducted from assets to which they apply: Allowances for doubtful accounts $ 754 $ 389 $ — $ (396 ) $ 747 Valuation allowance for deferred tax assets 6,101 1,032 7,133 Total $ 6,855 $ 1,421 $ — $ (396 ) $ 7,880 Year ended December 31, 2017 Allowances deducted from assets to which they apply: Allowances for doubtful accounts $ 747 $ 415 $ — $ (621 ) $ 541 Valuation allowance for deferred tax assets 7,133 1,152 (3,991 ) 4,294 Total $ 7,880 $ 1,567 $ — $ (4,612 ) $ 4,835

Nature Of Business And Summar30

Nature Of Business And Summary Of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation —The consolidated financial statements include the accounts of Great Lakes Dredge & Dock Corporation and its majority-owned subsidiaries. All intercompany accounts and transactions are eliminated in consolidation. The equity method of accounting is used for investments in unconsolidated investees in which the Company has significant influence, but not control. Other investments, if any, are carried at cost.
Use of Estimates	Use of Estimates —The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect certain reported amounts and disclosures. Accordingly, actual results could differ from those estimates.
Revenue and Cost Recognition on Contracts	Revenue and Cost Recognition on Contracts —Substantially all of the Company’s contracts for dredging services are fixed-price contracts, which provide for remeasurement based on actual quantities dredged. The majority of the Company’s environmental & infrastructure contracts, previously referred to as environmental & remediation, are also fixed-price contracts, with others performed on a time-and-materials basis. Contract revenues are recognized under the percentage-of-completion method based on the Company’s engineering estimates of the physical percentage completed for dredging projects and based on costs incurred to date compared to total estimated costs for fixed-price environmental & infrastructure projects. For dredging projects, costs of contract revenues are adjusted to reflect the gross profit percentage expected to be achieved upon ultimate completion. For environmental & infrastructure contracts, contract revenues are adjusted to reflect the estimated gross profit percentage. Revisions in estimated gross profit percentages are recorded in the period during which the change in circumstances is experienced or becomes known. As the duration of most of the Company’s contracts is one year or less, the cumulative net impact of these revisions in estimates, individually and in the aggregate across our projects, does not significantly affect our results across annual reporting periods. Provisions for estimated losses on contracts in progress are made in the period in which such losses are determined. Change orders are not recognized in revenue until the recovery is probable and collectability is reasonably assured. Claims for additional compensation due to the Company are not recognized in contract revenues until such claims are settled. Billings on contracts are generally submitted after verification with the customers of physical progress and may not match the timing of revenue recognition. The difference between amounts billed and recognized as revenue is reflected in the balance sheet as either contract revenues in excess of billings or billings in excess of contract revenues. Modifications may be negotiated when a change from the original contract specification is encountered, and a change in project scope, performance methodology and/or material disposal is necessary. Thus, the resulting modification is considered a change in the scope of the original project to which it relates. Significant expenditures incurred incidental to major contracts are deferred and recognized as contract costs based on contract performance over the duration of the related project. These expenditures are reported as prepaid expenses. The components of costs of contract revenues include labor, equipment (including depreciation, maintenance, insurance and long-term rentals), subcontracts, fuel, supplies, short-term rentals and project overhead. Project costs, excluding labor, have averaged approximately 23% of total costs of contract revenues over the prior three years. Hourly labor generally is hired on a project-by-project basis. Much of our domestic dredging hourly labor force is represented by labor unions with collective bargaining agreements that expire at various dates during 2018 through 2023, which historically have been extended without disruption. The environmental & infrastructure segment’s hourly labor force is made up of union and non-union employees. During the year, both dredging 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 dredging revenues recognized over the year, to better match revenues and expenses. Specifically, at each interim reporting date the Company compares actual dredging revenues earned to date on the Company’s dredging contracts to expected annual revenues and recognizes dredging 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. As a result of this methodology, the recorded expense in any interim period may be higher or lower than the actual equipment costs incurred in that interim period. For some environmental & infrastructure contracts, the Company has entered into unincorporated construction joint ventures under which certain portions of a larger project are performed. These investments are accounted for under the proportionate consolidation method for income statement reporting and under the equity method for balance sheet reporting. The Company’s interests in any profits and assets and proportionate share in any losses and liabilities are recognized based on the Company’s stated percentage partnership interest in the project. For projects related to proportionately consolidated joint ventures, we include only the Company’s percentage ownership of each joint venture's backlog.
Classification of Current Assets and Liabilities	Classification of Current Assets and Liabilities —The Company includes in current assets and liabilities amounts realizable and payable in the normal course of contract completion, unless completion of such contracts extends significantly beyond one year.
Cash Equivalents	Cash Equivalents —The Company considers all highly liquid investments with a maturity at purchase of three months or less to be cash equivalents.
Accounts Receivable	Accounts Receivable —Accounts receivable represent amounts due or billable under the terms of contracts with customers, including amounts related to retainage. The Company anticipates collection of retainage generally within one year, and accordingly presents retainage as a current asset. The Company provides an allowance for estimated uncollectible accounts receivable when events or conditions indicate that amounts outstanding are not recoverable.
Inventories	Inventories —Inventories consist of pipe and spare parts used in the Company’s dredging operations. Pipe and spare parts are purchased in large quantities; therefore, a certain amount of pipe and spare part inventories is not anticipated to be used within the current year and is classified as long-term. Spare part inventories are stated at weighted average historical cost, and are charged to expense when used in operations. Pipe inventory is recorded at cost and amortized to expense over the period of its use.
Property, Plant and Equipment	Property and Equipment —Capital additions, improvements, and major renewals are classified as property and equipment and are carried at depreciated cost. Maintenance and repairs that do not significantly extend the useful lives of the assets or enhance the capabilities of such assets are charged to expenses as incurred. Depreciation is recorded over the estimated useful lives of property and equipment using the straight-line method and the mid-year depreciation convention. The estimated useful lives by class of assets are: Class Useful Life (years) Buildings and improvements 10 Furniture and fixtures 5-10 Vehicles, dozers, and other light operating equipment and systems 3-5 Heavy operating equipment (dredges and barges) 10-30 Leasehold improvements are amortized over the shorter of their remaining useful lives or the remaining terms of the leases.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets —Goodwill represents the excess of acquisition cost over fair value of the net assets acquired. Other identifiable intangible assets mainly represent developed technology and databases, customer relationships, and customer contracts acquired in business combinations and are being amortized over a one to five-year period. Goodwill is tested annually for impairment in the third quarter of each year, or more frequently should circumstances dictate. GAAP requires that goodwill of a reporting unit be tested for impairment between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The Company assesses the fair values of its reporting units using both a market-based approach and an income-based approach. Under the income approach, the fair value of the reporting unit is based on the present value of estimated future cash flows. The income approach is dependent on a number of factors, including estimates of future market growth trends, forecasted revenues and expenses, appropriate discount rates and other variables. The estimates are based on assumptions that the Company believes to be reasonable, but such assumptions are subject to unpredictability and uncertainty. Changes in these estimates and assumptions could materially affect the determination of fair value, and may result in the impairment of goodwill in the event that actual results differ from those estimates. The market approach measures the value of a reporting unit through comparison to comparable companies. Under the market approach, the Company uses the guideline public company method by applying estimated market-based enterprise value multiples to the reporting unit’s estimated revenue and Adjusted EBITDA. The Company analyzes companies that performed similar services or are considered peers. Due to the fact that there are no public companies that are direct competitors, the Company weighs the results of this approach less than the income approach. The Company has two operating segments: dredging and environmental & infrastructure, which are also the Company’s two reportable segments and reporting units.
Long-Lived Assets	Long-Lived Assets —Long-lived assets are comprised of property and equipment and intangible assets subject to amortization. Long-lived assets to be held and used are reviewed for possible impairment whenever events indicate that the carrying amount of such assets may not be recoverable by comparing the undiscounted cash flows associated with the assets to their carrying amounts. If such a review indicates an impairment, the carrying amount would be reduced to fair value. No triggering events were identified in 2017 or 2016. If long-lived assets are to be disposed, depreciation is discontinued, if applicable, and the assets are reclassified as held for sale at the lower of their carrying amounts or fair values less estimated costs to sell.
Self-insurance Reserves	Self-insurance Reserves —The Company self-insures costs associated with its seagoing employees covered by the provisions of Jones Act, workers’ compensation claims, hull and equipment liability, and general business liabilities up to certain limits. Insurance reserves are established for estimates of the loss that the Company may ultimately incur on reported claims, as well as estimates of claims that have been incurred but not yet reported. In determining its estimates, the Company considers historical loss experience and judgments about the present and expected levels of cost per claim. Trends in actual experience are a significant factor in the determination of such reserves.
Income Taxes	Income Taxes —The provision for income taxes includes federal, foreign, and state income taxes currently payable and those deferred because of temporary differences between the financial statement and tax basis of assets and liabilities. Recorded deferred income tax assets and liabilities are based on the estimated future tax effects of differences between the financial and tax basis of assets and liabilities, given the effect of currently enacted tax laws. The Company’s current policy is to repatriate all earnings from foreign subsidiaries’ operations as generated and at this time no amounts are considered to be permanently reinvested in those operations. On December 22, 2017, the U.S. government enacted comprehensive tax legislation referred to as the Tax Cuts and Jobs Act. See Note 10.
Hedging Instruments	Hedging Instruments —At times, the Company designates certain derivative contracts as a cash flow hedge as defined by GAAP. Accordingly, the Company formally documents, at the inception of each hedge, all relationships between hedging instruments and hedged items, as well as our risk-management objective and strategy for undertaking hedge transactions. This process includes linking all derivatives to highly-probable forecasted transactions. The Company formally assesses, at inception and on an ongoing basis, the effectiveness of hedges in offsetting changes in the cash flows of hedged items. Hedge accounting treatment may be discontinued when (1) it is determined that the derivative is no longer highly effective in offsetting changes in the cash flows of a hedged item (including hedged items for forecasted future transactions), (2) the derivative expires or is sold, terminated or exercised, (3) it is no longer probable that the forecasted transaction will occur or (4) management determines that designating the derivative as a hedging instrument is no longer appropriate. If management elects to stop hedge accounting, it would be on a prospective basis and any hedges in place would be recognized in accumulated other comprehensive income (loss) until all the related forecasted transactions are completed or are probable of not occurring.
Foreign Currency Translation	Foreign Currency Translation —The financial statements of the Company’s foreign subsidiaries where the operations are primarily denominated in the foreign currency are translated into U.S. dollars for reporting. Balance sheet accounts are translated at the current foreign exchange rate at the end of each period and income statement accounts are translated at the average foreign exchange rate for each period. Gains and losses on foreign currency translations are reflected as a currency translation adjustment, net of tax, in accumulated other comprehensive income (loss). Foreign currency transaction gains and losses are included in other income (expense).
Recent Accounting Pronouncements	Recent Accounting Pronouncements — In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update No. 2017-04 (“ASU 2017-04”), Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . The amendment removes the requirement to compare the implied fair value of goodwill with its carrying amount as part of step 2 of the goodwill impairment test. The guidance is effective for fiscal years beginning after December 15, 2019. The Company does not anticipate that the adoption of ASU 2017-04 will have a material effect on the Company’s consolidated financial statements. In November 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update No. 2016-18 (“ASU 2016-18”), Statement of Cashflows (Topic 230): Restricted Cash. The Company does not anticipate that the adoption of ASU 2016-18 will have a material effect on the Company’s consolidated financial statements. In August 2016, the FASB issued Accounting Standard Update No. 2016-15 (“ASU 2016-15”), Classification of Certain Cash Receipts and Cash Payments The Company does not anticipate that the adoption of ASU 2016-15 will have a material effect on the Company’s consolidated financial statements. In February 2016, the FASB issued Accounting Standard Update No. 2016-02 (“ASU 2016-02”), Leases (Topic 842) In May 2014, the FASB issued Accounting Standard Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) Accounting Standard Updates related to Accounting Standards Codification Topic 606 (collectively, “ASC 606”)

Nature Of Business And Summar31

Nature Of Business And Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Estimated Useful Lives By Class Of Assets	The estimated useful lives by class of assets are: Class Useful Life (years) Buildings and improvements 10 Furniture and fixtures 5-10 Vehicles, dozers, and other light operating equipment and systems 3-5 Heavy operating equipment (dredges and barges) 10-30

Earnings Per share (Tables)

Earnings Per share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Computations For Basic And Diluted Loss Per Share	The computations for basic and diluted loss per share for the years ended December 31, 2017, 2016 and 2015 are as follows: (shares in thousands) 2017 2016 2015 Loss from continuing operations $ (18,563 ) $ (8,177 ) $ (6,189 ) Loss on discontinued operations, net of income taxes, attributable to Great Lakes Dredge & Dock Corporation (12,697 ) — — Net loss attributable to common stockholders of Great Lakes Dredge & Dock Corporation $ (31,260 ) $ (8,177 ) $ (6,189 ) Weighted-average common shares outstanding — basic 61,365 60,744 60,410 Effect of stock options and restricted stock units — — — Weighted-average common shares outstanding — diluted 61,365 60,744 60,410 Loss per share from continuing operations — basic $ (0.30 ) $ (0.13 ) $ (0.10 ) Loss per share from continuing operations — diluted $ (0.30 ) $ (0.13 ) $ (0.10 )

Accounts Receivable And Contr33

Accounts Receivable And Contracts In Progress (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Schedule Of Accounts Receivable	Accounts receivable at December 31, 2017 and 2016 are as follows: 2017 2016 Completed contracts $ 15,974 $ 18,727 Contracts in progress 42,759 53,137 Retainage 21,866 21,399 80,599 93,263 Allowance for doubtful accounts (591 ) (747 ) Total accounts receivable—net $ 80,008 $ 92,516 Current portion of accounts receivable—net $ 75,533 $ 88,091 Long-term accounts receivable and retainage 4,475 4,425 Total accounts receivable—net $ 80,008 $ 92,516
Components Of Contracts In Progress	The components of contracts in progress at December 31, 2017 and 2016 are as follows: 2017 2016 Costs and earnings in excess of billings: Costs and earnings for contracts in progress $ 558,557 $ 587,371 Amounts billed (490,732 ) (511,548 ) Costs and earnings in excess of billings for contracts in progress 67,825 75,823 Costs and earnings in excess of billings for completed contracts 22,963 19,189 Total contract revenues in excess of billings $ 90,788 $ 95,012 Billings in excess of costs and earnings: Amounts billed $ (325,350 ) $ (268,754 ) Costs and earnings for contracts in progress 321,735 263,613 Total billings in excess of contract revenues $ (3,615 ) $ (5,141 )

Property And Equipment (Tables)

Property And Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Schedule Of Property Plant And Equipment	2017 2016 Land $ 9,992 $ 9,992 Buildings and improvements 5,092 5,133 Furniture and fixtures 12,990 11,998 Operating equipment 805,748 788,989 Total property and equipment 833,822 816,112 Accumulated depreciation (426,528 ) (403,104 ) Property and equipment — net $ 407,294 $ 413,008

Goodwill And Other Intangible35

Goodwill And Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule Of Goodwill	The change in the carrying amount of goodwill during the years ended December 31, 2017 and 2016 is as follows: Dredgin g Environmental & Infrastructur e Total Balance - January 1, 2015 $ 76,576 $ 9,750 $ 86,326 Impairment of goodwill — (2,750 ) (2,750 ) Balance - December 31, 2016 76,576 7,000 83,576 Balance - December 31, 2017 $ 76,576 $ 7,000 $ 83,576
Net Book Value Of Identifiable Intangible Assets	At December 31, 2017 and 2016, the net book value of identifiable intangible assets was as follows: As of December 31, 2017 Cost Accumulated Amortization Net Non-compete agreements $ 2,377 $ 1,753 $ 624 Other 781 497 284 $ 3,158 $ 2,250 $ 908 As of December 31, 2016 Non-compete agreements $ 2,377 $ 1,317 $ 1,060 Other 781 342 439 $ 3,158 $ 1,659 $ 1,499

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued Expenses	Accrued expenses at December 31, 2017 and 2016 are as follows: 2017 2016 Insurance $ 22,941 $ 18,114 Payroll and employee benefits 8,747 10,028 Accrued rent 6,519 738 Interest 4,210 8,660 Percentage of completion adjustment 3,591 3,322 Income and other taxes 2,794 3,208 Accumulated deficit in joint venture — 17,016 Other 7,416 7,957 Total accrued expenses $ 56,218 $ 69,043

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	Long-term debt at December 31, 2017 and 2016 is as follows: 2017 2016 Revolving credit facility $ 95,000 $ 104,111 Equipment notes payable 2,318 2,680 Notes payable 13,296 14,438 8% senior notes 321,057 — 7.375% senior notes — 272,998 Subtotal 431,671 394,227 Current portion of equipment note payable (1,546 ) (1,320 ) Current portion of note payable (1,212 ) (1,145 ) Capital leases (included in other long term liabilities) (772 ) (1,360 ) Total $ 428,141 $ 390,402
Maturities Of Long-Term Debt	The scheduled principal payments through the maturity date of the Company’s long-term debt, excluding equipment notes and capital leases, at December 31, 2017, are as follows: Years Ending December 31, 2018 $ 1,212 2019 96,502 2020 1,816 2021 1,922 2022 327,035 Thereafter 4,843 Total $ 433,330

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule Of Fair Values Of Financial Instruments And Nonfinancial Assets And Liabilities Measured At The Reporting Date	The fair values of these financial instruments are summarized as follows: Fair Value Measurements at Reporting Date Using Description At December 31, 2017 Quoted Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable (Level 3) Fuel hedge contracts $ 2,501 $ — $ 2,501 $ — Fair Value Measurements at Reporting Date Using Description At December 31, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fuel hedge contracts $ 2,293 $ — $ 2,293 $ —
Schedule Of Fair Value Of Fuel Hedge Contracts Balance Sheet Location	The fair value of the fuel hedge contracts outstanding as of December 31, 2017 and 2016 is as follows: Balance Sheet Location Fair Value at December 31, 2017 2016 Asset derivatives: Derivatives designated as hedging instruments Fuel hedge contracts Other current assets 2,501 546 Derivatives not designated as hedging instruments Fuel hedge contracts Other current assets 1,747 Total asset derivatives $ 2,501 $ 2,293
Schedule Of Fair Value Measurements Of Goodwill Using Significant Unobservable Inputs	The fair value of goodwill was determined using quantitative models that contained significant unobservable inputs and accordingly is a Level 3 fair value measurement. See Note 6. Fair Goodwill Balance at January 1, $ 86,326 Impairment of goodwill (2,750 ) Balance at December 31, 2015 $ 83,576
Changes In Components Of Accumulated Other Comprehensive Income (Loss)	Changes in the components of the accumulated balances of other comprehensive income (loss) are as follows: 2017 2016 2015 Cumulative translation adjustments—net of tax $ (41 ) $ 508 $ (1,249 ) Derivatives: Reclassification of derivative (gains) losses to earnings—net of tax (218 ) 30 — Change in fair value of derivatives—net of tax 1,407 300 — Net unrealized (gain) loss on derivatives—net of tax 1,189 330 — Total other comprehensive income (loss) $ 1,148 $ 838 $ (1,249 )
Adjustments Reclassified From Accumulated Balances Other Comprehensive Income (Loss) To Earnings	Adjustments reclassified from accumulated balances of other comprehensive income (loss) to earnings are as follows: Statement of Operations Location 2017 2016 Derivatives: Fuel hedge contracts Costs of contract revenues $ (358 ) $ 50 Income tax benefit 140 20 $ (218 ) $ 30

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income tax Benefit from Continuing and Discontinuing Operations	2017 Income tax benefit from continuing operations $ 35,610 Income tax benefit from discontinued operations 8,203 Income tax benefit $ 43,813
Loss From Continuing Operations Before Income Tax From Domestic And Foreign Operations	2017 2016 2015 Domestic operations $ (17,307 ) $ (2,295 ) $ (35,996 ) Foreign operations (36,866 ) (11,674 ) 27,310 Total loss from continuing operations before income tax $ (54,173 ) $ (13,969 ) $ (8,686 )
Benefit For Income Taxes	2017 2016 2015 Federal: Current $ (248 ) 260 $ — Deferred (33,592 ) (5,098 ) (2,355 ) State: Current 29 54 115 Deferred (1,812 ) (1,153 ) (673 ) Foreign: Current 13 146 416 Deferred — — — Total $ (35,610 ) $ (5,791 ) $ (2,497 )
Income Tax Benefit Reconciliation	2017 2016 2015 Tax benefit at statutory U.S. federal income tax rate $ (18,958 ) $ (4,889 ) $ (3,040 ) State income tax — net of federal income tax benefit (2,488 ) (1,118 ) (676 ) Impact of Tax Cuts and Job Act (15,720 ) — — Charitable contributions — — (469 ) Adjustment to deferred tax depreciation — — 1,135 Change in deferred state tax rate — (1,082 ) — Research and development tax credits (170 ) (253 ) (286 ) Purchase price adjustment — — 393 Changes in unrecognized tax benefits 10 10 (186 ) Changes in valuation allowance 1,152 1,031 270 Other 564 510 362 Income tax benefit $ (35,610 ) $ (5,791 ) $ (2,497 )
Reconciliation Of Unrecognized Tax Benefits	2017 2016 2015 Unrecognized tax benefits — January 1 $ 157 $ 157 $ 442 Gross increases — tax positions in prior period — — — Gross increases — current period tax positions — — — Gross decreases — expirations — — — Gross decreases — tax positions in prior period — — (285 ) Unrecognized tax benefits — December 31, $ 157 $ 157 $ 157
Deferred Tax Assets (Liabilities)	2017 2016 Deferred tax assets: Accrued liabilities $ 8,119 $ 16,194 Federal NOLs 43,654 17,905 Foreign NOLs 1,962 3,795 State NOLs 12,382 5,989 Tax credit carryforwards 1,941 5,970 Charitable contribution 1,340 1,883 Valuation allowance (4,294 ) (7,133 ) Total deferred tax assets 65,104 44,603 Deferred tax liabilities: Depreciation and amortization (89,966 ) (111,793 ) Other liabilities (699 ) (1,259 ) Total deferred tax liabilities (90,665 ) (113,052 ) Net noncurrent deferred tax liabilities $ (25,561 ) $ (68,449 )

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary Of Stock Option Activity	A summary of stock option activity under the Incentive Plan as of December 31, 2017, and changes during the year ended December 31, 2017, is presented below: Options Shares Weighted Exercise Price Weighted-Average Remaining Contract Term (yrs) Aggregate Intrinsic Value ($000's) Outstanding as of January 1, 2017 1,699 $ 6.32 Granted — — Exercised (4 ) 3.82 Forfeited or Expired (318 ) 6.26 Outstanding as of December 31, 2017 1,377 $ 6.34 3.4 $ 195 Vested at December 31, 2017 1,377 $ 6.34 3.4 $ 195
Summary Of Non-Vested Restricted Stock Units	A summary of the status of the Company’s non-vested RSUs as of December 31, 2017, and changes during the year ended December 31, 2017, is presented below: Nonvested Restricted Stock Units Shares Weighted-Average Grant-Date Fair Value Outstanding as of January 1, 2017 2,532 $ 5.23 Granted 1,018 4.42 Vested (222 ) 5.66 Forfeited (1,132 ) 5.72 Outstanding as of December 31, 2017 2,196 $ 5.06 Expected to vest at December 31, 2017 1,430 $ 4.60

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Schedule of Significant Multiemployer Pension Plans	Information on significant multiemployer pension plans in which the Company participates is included in the table below: Pension Protection Act of 2006 Certified Zone Status at December 31, Company's Contributions Pension Plan Legal Name Federal Identification Number 2017 2016 Expiration of Collective Bargaining Arrangement with the Company 2017 2016 2015 Seafarers Pension Trust 13-6100329 001 Green Green February 28, 2018 $ 1,182 $ 1,102 $ 1,005

Restructuring charges (Tables)

Restructuring charges (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Schedule of Restructuring Charges	Restructuring charges currently recognized for the above actions are summarized as follows: Twelve Months Ended December 31, 2017 Costs of contract revenues - depreciation $ 6,859 Costs of contract revenues - other 16,102 General and administrative expenses 1,189 Loss on sale of assets—net 4,691 Total Dredging 28,841 Costs of contract revenues - depreciation — Costs of contract revenues - other 7 General and administrative expenses 637 Total Environmental & Infrastructure 644 Costs of contract revenues - depreciation 6,859 Costs of contract revenues - other 16,109 General and administrative expenses 1,826 Loss on sale of assets—net 4,691 Total Consolidated 29,485

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Operating Lease Payments	Future minimum operating lease payments at December 31, 2017, are as follows: 2018 $ 21,310 2019 17,119 2020 14,365 2021 12,500 2022 8,773 Thereafter 8,408 Total minimum operating lease payments $ 82,475

Investment (Tables)

Investment (Tables)	12 Months Ended
	Dec. 31, 2017
Amboy Aggregates [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investments	The Company accounts for this investment under the equity method. The following is summarized financial information for this dissolved entity: 2017 2016 2015 Revenue $ — $ — $ 139 Gross profit (loss) — 758 (1,363 ) Income (loss) from continuing operations 34 758 (3,152 ) Net income (loss) 34 758 (3,152 )
TerraSea Environmental Solutions [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investments	The Company accounts for this investment under the equity method. The following is summarized financial information for this dissolved entity: 2016 2015 Revenue $ — $ 6,960 Gross loss (183 ) (3,800 ) Net loss (183 ) (3,800 )

Business Combinations And Dis45

Business Combinations And Dispositions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Schedule Of Discontinued Operations	The Company estimated its exposure to a surety bond claim, including associated expense to be $20,900 and has recorded this amount in discontinued operations for the year ended December 31, 2017 as follow: 2017 Revenue $ — Loss before income taxes from discontinued operations $ (20,900 ) Income tax benefit 8,203 Loss from discontinued operations, net of income taxes $ (12,697 )

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Reporting By Segment	2017 2016 2015 Dredging: Contract revenues $ 592,159 $ 637,468 $ 681,255 Operating income (loss) (13,353 ) 34,108 64,073 Depreciation and amortization 55,962 54,826 50,556 Total assets 878,458 912,880 872,297 Property and equipment—net 396,925 399,479 397,468 Goodwill 76,576 76,576 76,576 Investment in joint ventures — 381 1 Capital expenditures 63,912 84,263 82,000 Environmental & infrastructure: Contract revenues 112,607 133,637 181,710 Operating loss (10,172 ) (19,428 ) (41,114 ) Depreciation and amortization 4,558 8,197 14,029 Total assets 78,806 81,166 127,907 Property and equipment—net 10,369 13,529 32,742 Goodwill 7,000 7,000 7,000 Investment in joint ventures 2,714 4,353 3,760 Capital expenditures 2,156 949 7,279 Intersegment: Contract revenues (2,263 ) (3,520 ) (6,087 ) Total assets (124,907 ) (100,458 ) (102,080 ) Total: Contract revenues 702,503 767,585 856,878 Operating income (loss) (23,525 ) 14,680 22,959 Depreciation and amortization 60,520 63,023 64,585 Total assets 832,357 893,588 898,124 Property and equipment—net 407,294 413,008 430,210 Goodwill 83,576 83,576 83,576 Investment in joint ventures 2,714 4,734 3,761 Capital expenditures 66,068 85,212 89,279
Revenue Related to Dredging Projects By Type Of Work	2017 2016 2015 Capital dredging — U.S. $ 185,113 $ 219,914 $ 207,058 Capital dredging — foreign 42,306 59,413 139,945 Coastal protection dredging 191,070 215,041 184,060 Maintenance dredging 134,923 92,274 120,055 Rivers & lakes 38,747 50,826 30,137 Total dredging $ 592,159 $ 637,468 $ 681,255
Revenues And Gross Profit From Foreign Project Operations	2017 2016 2015 Contract revenues $ 42,306 $ 59,413 $ 139,945 Costs of contract revenues (73,958 ) (66,729 ) (105,951 ) Gross profit $ (31,652 ) $ (7,316 ) $ 33,994

Subsidiary Guarantors (Tables)

Subsidiary Guarantors (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Balance Sheet	GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2017 (In thousands) ASSETS Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated CURRENT ASSETS: Cash and cash equivalents $ 15,794 $ 38 $ 20 $ — $ 15,852 Accounts receivable — net 75,431 102 — — 75,533 Contract revenues in excess of billings 90,788 — — — 90,788 Inventories 34,600 — — — 34,600 Prepaid expenses 5,183 — — — 5,183 Other current assets 38,731 1,497 — — 40,228 Total current assets 260,527 1,637 20 — 262,184 PROPERTY AND EQUIPMENT—Net 407,293 1 — — 407,294 GOODWILL 83,576 — — — 83,576 OTHER INTANGIBLE ASSETS—Net 571 337 — — 908 INVENTORIES — Noncurrent 54,023 — — — 54,023 INVESTMENTS IN JOINT VENTURES 2,555 159 — — 2,714 ASSETS HELD FOR SALE— Noncurrent 8,530 — — — 8,530 RECEIVABLES FROM AFFILIATES 45,375 6,754 170,323 (222,452 ) — INVESTMENTS IN SUBSIDIARIES — — 511,435 (511,435 ) — OTHER 7,971 1 5,156 — 13,128 TOTAL $ 870,421 $ 8,889 $ 686,934 $ (733,887 ) $ 832,357 LIABILITIES AND EQUITY CURRENT LIABILITIES: Accounts payable $ 87,379 $ 280 $ — $ — $ 87,659 Accrued expenses 50,382 1,312 4,524 — 56,218 Billings in excess of contract revenues 3,615 — — — 3,615 Current portion of long-term debt 1,546 — 1,212 — 2,758 Total current liabilities 142,922 1,592 5,736 — 150,250 LONG-TERM DEBT — — 333,141 — 333,141 REVOLVING CREDIT FACILITY — — 95,000 — 95,000 DEFERRED INCOME TAXES — — 25,561 — 25,561 PAYABLES TO AFFILIATES 161,979 54,442 6,031 (222,452 ) — INVESTMENTS IN SUBSIDIARIES 41,358 — — (41,358 ) — OTHER 6,940 — 169 — 7,109 Total liabilities 353,199 56,034 465,638 (263,810 ) 611,061 TOTAL EQUITY 517,222 (47,145 ) 221,296 (470,077 ) 221,296 TOTAL $ 870,421 $ 8,889 $ 686,934 $ (733,887 ) $ 832,357 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2016 (In thousands) ASSETS Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated CURRENT ASSETS: Cash and cash equivalents $ 10,414 $ 751 $ 2 $ — $ 11,167 Accounts receivable — net 75,412 14,242 — (1,563 ) 88,091 Contract revenues in excess of billings 91,478 3,534 — — 95,012 Inventories 37,137 — — — 37,137 Prepaid expenses 12,287 120 — — 12,407 Other current assets 60,844 2,568 — — 63,412 Total current assets 287,572 21,215 2 (1,563 ) 307,226 PROPERTY AND EQUIPMENT—Net 407,516 5,492 — — 413,008 GOODWILL 83,576 — — — 83,576 OTHER INTANGIBLE ASSETS—Net 1,067 432 — — 1,499 INVENTORIES — Noncurrent 52,602 — — — 52,602 INVESTMENTS IN JOINT VENTURES 4,685 49 — — 4,734 ASSETS HELD FOR SALE— Noncurrent 8,390 909 — — 9,299 RECEIVABLES FROM AFFILIATES 58,284 16,807 82,340 (157,431 ) — INVESTMENTS IN SUBSIDIARIES — — 636,216 (636,216 ) — OTHER 14,692 1 6,951 — 21,644 TOTAL $ 918,384 $ 44,905 $ 725,509 $ (795,210 ) $ 893,588 LIABILITIES AND EQUITY CURRENT LIABILITIES: Accounts payable $ 101,795 $ 2,879 $ 17 $ (1,506 ) $ 103,185 Accrued expenses 55,940 3,222 9,881 — 69,043 Billings in excess of contract revenues 4,699 499 — (57 ) 5,141 Current portion of long term-debt 305 1,015 1,145 — 2,465 Total current liabilities 162,739 7,615 11,043 (1,563 ) 179,834 LONG-TERM DEBT — — 286,291 — 286,291 REVOLVING CREDIT FACILITY — — 104,111 — 104,111 DEFERRED INCOME TAXES (1,833 ) — 70,282 — 68,449 PAYABLES TO AFFILIATES 80,769 70,921 5,741 (157,431 ) — INVESTMENTS IN SUBSIDIARIES 32,000 — — (32,000 ) — OTHER 5,925 937 151 — 7,013 Total liabilities 279,600 79,473 477,619 (190,994 ) 645,698 TOTAL EQUITY 638,784 (34,568 ) 247,890 (604,216 ) 247,890 TOTAL $ 918,384 $ 44,905 $ 725,509 $ (795,210 ) $ 893,588
Condensed Consolidating Statement of Operations and Comprehensive Income (Loss)	GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE LOSS FOR THE YEAR ENDED DECEMBER 31, 2017 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals Contract revenues $ 699,607 $ 5,163 $ — $ (2,267 ) $ 702,503 Costs of contract revenues (647,467 ) (7,420 ) — 2,267 (652,620 ) Gross profit 52,140 (2,257 ) — — 49,883 OPERATING EXPENSES: General and administrative expenses 67,175 1,156 — — 68,331 Loss on sale of assets—net 4,801 276 — — 5,077 Operating loss (19,836 ) (3,689 ) — — (23,525 ) Interest income (expense)—net 1,054 (966 ) (26,134 ) — (26,046 ) Equity in earnings (loss) of subsidiaries 38 — (26,973 ) 26,935 — Equity in loss of joint ventures (1,484 ) — — — (1,484 ) Loss on extinguishment of debt — — (2,330 ) — (2,330 ) Other income (expense) (1,240 ) 452 — — (788 ) Loss from continuing operations before income taxes (21,468 ) (4,203 ) (55,437 ) 26,935 (54,173 ) Income tax (provision) benefit (1,250 ) (14 ) 36,874 — 35,610 Loss from continuing operations (22,718 ) (4,217 ) (18,563 ) 26,935 (18,563 ) Loss from discontinued operations, net of income taxes (20,900 ) — (12,697 ) 20,900 (12,697 ) Net loss $ (43,618 ) $ (4,217 ) $ (31,260 ) $ 47,835 $ (31,260 ) Comprehensive loss $ (42,429 ) $ (4,258 ) $ (30,112 ) $ 46,687 $ (30,112 ) GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE YEAR ENDED DECEMBER 31, 2016 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals Contract revenues $ 726,239 $ 44,086 $ — $ (2,740 ) $ 767,585 Costs of contract revenues (622,158 ) (61,779 ) — 2,740 (681,197 ) Gross profit 104,081 (17,693 ) — — 86,388 OPERATING EXPENSES: General and administrative expenses 51,678 13,904 (49 ) — 65,533 Loss on sale of assets—net 3,040 3,135 — — 6,175 Operating income (loss) 49,363 (34,732 ) 49 — 14,680 Interest income (expense)—net 1,985 (1,497 ) (23,395 ) — (22,907 ) Equity in earnings (loss) of subsidiaries (31,488 ) — 10,313 21,175 — Equity in loss of joint ventures (2,365 ) — — — (2,365 ) Other expense (2,626 ) (751 ) — — (3,377 ) Income (loss) before income taxes 14,869 (36,980 ) (13,033 ) 21,175 (13,969 ) Income tax (provision) benefit 1,080 (144 ) 4,856 — 5,792 Net income (loss) $ 15,949 $ (37,124 ) $ (8,177 ) $ 21,175 $ (8,177 ) Comprehensive income (loss) $ 16,279 $ (36,616 ) $ (7,339 ) $ 20,337 $ (7,339 ) GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE YEAR ENDED DECEMBER 31, 2015 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Corporation Eliminations Consolidated Totals Contract revenues $ 778,337 $ 86,666 $ — $ (8,125 ) $ 856,878 Costs of contract revenues (670,973 ) (98,107 ) — 8,125 (760,955 ) Gross profit 107,364 (11,441 ) — — 95,923 OPERATING EXPENSES: General and administrative expenses 58,682 12,387 — — 71,069 Impairment of goodwill — 2,750 — — 2,750 (Gain) loss on sale of assets—net (885 ) 30 — — (855 ) Operating income 49,567 (26,608 ) — — 22,959 Interest income (expense)—net 872 (1,398 ) (23,839 ) — (24,365 ) Equity in earnings of subsidiaries 34 — 16,282 (16,316 ) — Equity in earnings (loss) of joint ventures (6,221 ) 170 — — (6,051 ) Other income (loss) (3,180 ) 1,951 — — (1,229 ) Income (loss) before income taxes 41,072 (25,885 ) (7,557 ) (16,316 ) (8,686 ) Income tax (provision) benefit 1,641 (512 ) 1,368 — 2,497 Net income (loss) $ 42,713 $ (26,397 ) $ (6,189 ) $ (16,316 ) $ (6,189 ) Comprehensive income (loss) $ 42,713 $ (27,646 ) $ (7,438 ) $ (15,067 ) $ (7,438 )
Condensed Consolidating Statement of Cash Flows	GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2017 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals OPERATING ACTIVITIES: Net cash flows provided by operating activities of continuing operations $ 64,610 $ 4,910 $ (27,102 ) $ — $ 42,418 Net cash flows used in operating activities of discontinued operations (20,900 ) — — — (20,900 ) Cash provided by (used in) operating activities 43,710 4,910 (27,102 ) — 21,518 INVESTING ACTIVITIES: Purchases of property and equipment (75,940 ) 7,711 — — (68,229 ) Proceeds from dispositions of property and equipment 8,620 1,457 — — 10,077 Changes in restricted cash 7,035 — — — 7,035 Net change in accounts with affiliates 3,732 — (88,594 ) 84,862 — Transfer to parent — (9,615 ) 81,184 (71,569 ) — Cash used in investing activities (56,553 ) (447 ) (7,410 ) 13,293 (51,117 ) FINANCING ACTIVITIES: Proceeds from issuance of debt 1,241 — 325,000 326,241 Repayments of debt (1,602 ) — (276,148 ) — (277,750 ) 7 3/8% senior notes tender premium — — (744 ) — (744 ) Deferred financing fees — — (5,022 ) — (5,022 ) Taxes paid on settlement of vested share awards — — (328 ) — (328 ) Net change in accounts with affiliates 90,153 (5,291 ) — (84,862 ) — Transfer to parent (71,569 ) — — 71,569 — Exercise of stock options and purchases from employee stock plans — — 883 — 883 Borrowings under revolving loans — — 124,925 — 124,925 Repayments of revolving loans — — (134,036 ) — (134,036 ) Cash provided by (used in) financing activities 18,223 (5,291 ) 34,530 (13,293 ) 34,169 Effect of foreign currency exchange rates on cash and cash equivalents — 115 — — 115 Net increase (decrease) in cash and cash equivalents 5,380 (713 ) 18 — 4,685 Cash and cash equivalents at beginning of period 10,414 751 2 — 11,167 Cash and cash equivalents at end of period $ 15,794 $ 38 $ 20 $ — $ 15,852 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2016 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Eliminations Consolidated Totals OPERATING ACTIVITIES: Cash provided by (used in) operating activities $ 74,409 $ (16,677 ) $ (19,062 ) $ — $ 38,670 INVESTING ACTIVITIES: Purchases of property and equipment (83,777 ) (21 ) — — (83,798 ) Proceeds from dispositions of property and equipment 10,582 7,675 — — 18,257 Changes in restricted cash (7,035 ) — — — (7,035 ) Net change in accounts with affiliates (5,100 ) — (36,172 ) 41,272 — Transfer to parent — — 23,000 (23,000 ) — Cash provided by (used in) investing activities (85,330 ) 7,654 (13,172 ) 18,272 (72,576 ) FINANCING ACTIVITIES: Repayments of debt (296 ) (1,128 ) (45,661 ) — (47,085 ) Deferred financing fees — — (6,817 ) — (6,817 ) Taxes paid on settlement of vested share awards — — (171 ) — (171 ) Net change in accounts with affiliates 32,933 8,339 — (41,272 ) — Transfer to parent (23,000 ) — — 23,000 — Exercise of stock options and purchases from employee stock plans — — 905 — 905 Excess income tax benefit from share-based compensation — — (133 ) — (133 ) Borrowings under revolving loans — — 288,611 — 288,611 Repayments of revolving loans — — (204,500 ) — (204,500 ) Cash provided by financing activities 9,637 7,211 32,234 (18,272 ) 30,810 Effect of foreign currency exchange rates on cash and cash equivalents — 79 — — 79 Net decrease in cash and cash equivalents (1,284 ) (1,733 ) — — (3,017 ) Cash and cash equivalents at beginning of period 11,698 2,484 2 — 14,184 Cash and cash equivalents at end of period $ 10,414 $ 751 $ 2 $ — $ 11,167 GREAT LAKES DREDGE & DOCK CORPORATION AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2015 (In thousands) Subsidiary Guarantors Non-Guarantor Subsidiaries GLDD Corporation Eliminations Consolidated Totals OPERATING ACTIVITIES: Cash provided by (used in) operating activities 75,489 (22,679 ) (23,688 ) — 29,122 INVESTING ACTIVITIES: Purchases of property and equipment (70,759 ) (3,696 ) — — (74,455 ) Proceeds from dispositions of property and equipment 1,102 220 — — 1,322 Net change in accounts with affiliates (32,342 ) — (12,222 ) 44,564 — Cash used in investing activities (101,999 ) (3,476 ) (12,222 ) 44,564 (73,133 ) FINANCING ACTIVITIES: Proceeds from issuance of debt — — 3,050 — 3,050 Repayments of debt (195 ) (1,006 ) (5,443 ) — (6,644 ) Deferred financing fees — — (111 ) — (111 ) Taxes paid on settlement of vested share awards — — (267 ) — (267 ) Net change in accounts with affiliates (23,491 ) 31,991 36,064 (44,564 ) — Transfer to parent 17,258 — (17,258 ) — — Exercise of stock options and purchases from employee stock plans — — 1,365 — 1,365 Excess income tax benefit from share-based compensation — — (57 ) — (57 ) Purchase of treasury stock — — (1,433 ) — (1,433 ) Borrowings under revolving loans — — 179,500 — 179,500 Repayments of revolving loans — — (159,500 ) — (159,500 ) Cash provided by (used in) financing activities (6,428 ) 30,985 35,910 (44,564 ) 15,903 Effect of foreign currency exchange rates on cash and cash equivalents — (97 ) — — (97 ) Net increase (decrease) in cash and cash equivalents (32,938 ) 4,733 — — (28,205 ) Cash and cash equivalents at beginning of period 44,636 (2,249 ) 2 — 42,389 Cash and cash equivalents at end of period $ 11,698 $ 2,484 $ 2 $ — $ 14,184

Nature Of Business And Summar48

Nature Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)segment
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Average equipment-related costs of total costs of contract revenue	23.00%
Number of operating Segments	2
Number of reportable segments	2
Minimum [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Identifiable intangible asset useful life	1 year
Maximum [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Identifiable intangible asset useful life	5 years
Maximum [Member] | Accounting Standards Update 2014-09 [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Cumulative net adjustment to the beginning retained earnings balance | $	$ 5,000

Nature Of Business And Summar49

Nature Of Business And Summary Of Significant Accounting Policies (Estimated Useful Lives By Class Of Assets) (Details)	12 Months Ended
	Dec. 31, 2017
Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful life	10 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life	5 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life	10 years
Vehicles, Dozers, And Other Light Operating Equipment And Systems [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life	3 years
Vehicles, Dozers, And Other Light Operating Equipment And Systems [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life	5 years
Heavy Operating Equipment (Dredges And Barges) [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life	10 years
Heavy Operating Equipment (Dredges And Barges) [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life	30 years

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Shares excluded from computation of diluted earnings per share	2,476	1,594	1,179
Securities excluded from computation of earnings per share amount due to loss	716	623	431

Earnings Per Share - (Computati

Earnings Per Share - (Computations For Basic And Diluted Loss Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Loss from continuing operations	$ (18,563)	$ (8,177)	$ (6,189)
Loss from discontinued operations, net of income taxes	(12,697)
NET LOSS	$ (31,260)	$ (8,177)	$ (6,189)
Weighted-average common shares outstanding — basic	61,365	60,744	60,410
Weighted-average common shares outstanding — diluted	61,365	60,744	60,410
Loss per share from continuing operations — basic	$ (0.30)	$ (0.13)	$ (0.10)
Loss per share from continuing operations — diluted	$ (0.30)	$ (0.13)	$ (0.10)

Restricted And Escrowed Cash (N

Restricted And Escrowed Cash (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 30, 2016
Cash And Cash Equivalents [Line Items]
Restricted cash	$ 3,742	$ 10,777
Cash collateral		7,035
Long-term Equipment Operating Lease [Member]
Cash And Cash Equivalents [Line Items]
Restricted cash		1,500
Other Noncurrent Assets [Member]
Cash And Cash Equivalents [Line Items]
Restricted cash	1,500	8,535
Other Current Assets [Member]
Cash And Cash Equivalents [Line Items]
Restricted cash	$ 2,242	$ 2,242

Accounts Receivable And Contr53

Accounts Receivable And Contracts In Progress (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Completed contracts	$ 15,974	$ 18,727
Contracts in progress	42,759	53,137
Retainage	21,866	21,399
Accounts receivable, gross	80,599	93,263
Allowance for doubtful accounts	(591)	(747)
Total accounts receivable—net	80,008	92,516
Current portion of accounts receivable—net	75,533	88,091
Long-term accounts receivable and retainage	$ 4,475	$ 4,425

Accounts Receivable And Contr54

Accounts Receivable And Contracts In Progress (Components Of Contracts In Progress) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Costs and earnings in excess of billings for contracts in progress	$ 67,825	$ 75,823
Costs and earnings in excess of billings for completed contracts	22,963	19,189
Total contract revenues in excess of billings	90,788	95,012
Total billings in excess of contract revenues	(3,615)	(5,141)
Costs And Earnings In Excess Of Billings [Member]
Accounts Notes And Loans Receivable [Line Items]
Costs and earnings for contracts in progress	558,557	587,371
Amounts billed	(490,732)	(511,548)
Billings In Excess Of Costs And Earnings [Member]
Accounts Notes And Loans Receivable [Line Items]
Costs and earnings for contracts in progress	321,735	263,613
Amounts billed	$ (325,350)	$ (268,754)

Accounts Receivable And Contr55

Accounts Receivable And Contracts In Progress (Narrative) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Receivables [Abstract]
Costs in excess of billings	$ 17,860

Property And Equipment (Details

Property And Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 833,822	$ 816,112
Accumulated depreciation	(426,528)	(403,104)
Property and equipment — net	407,294	413,008	$ 430,210
Land [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	9,992	9,992
Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	5,092	5,133
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	12,990	11,998
Operating Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 805,748	$ 788,989

Property And Equipment (Narrati

Property And Equipment (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
(Gain) loss on dispositions of property and equipment	$ 5,077	$ 6,175	$ (855)
Depreciation	59,927	61,694	$ 58,050
Operating Equipment [Member]
Property, Plant and Equipment [Line Items]
Operating equipment excluded from property and equipment held for sale	8,530	9,299
(Gain) loss on dispositions of property and equipment	$ 2,330	$ 2,744

Goodwill And Other Intangible58

Goodwill And Other Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended			24 Months Ended
	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016
Impairment of goodwill		$ 0		$ 2,750	$ 2,750
Amortization expense		591	$ 1,329	$ 6,535
2,018		534
2,019		214
2,020		80
2,021		$ 80
Terra Contracting Services [Member]
Impairment of goodwill	$ 2,750

Goodwill And Other Intangible59

Goodwill And Other Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended		24 Months Ended
	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2016
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 83,576	$ 86,326	$ 86,326
Impairment of goodwill	0	(2,750)	(2,750)
Goodwill, Ending Balance	83,576	83,576	83,576
Dredging Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	76,576	76,576	76,576
Impairment of goodwill	0		0
Goodwill, Ending Balance	76,576	76,576	76,576
Environmental & Remediation Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	7,000	$ 9,750	9,750
Impairment of goodwill	0		(2,750)
Goodwill, Ending Balance	$ 7,000		$ 7,000

Goodwill And Other Intangible60

Goodwill And Other Intangible Assets (Net Book Value Of Identifiable Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Cost	$ 3,158	$ 3,158
Accumulated amortization	2,250	1,659
Net	908	1,499
Non-compete Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Cost	2,377	2,377
Accumulated amortization	1,753	1,317
Net	624	1,060
Other [Member]
Finite Lived Intangible Assets [Line Items]
Cost	781	781
Accumulated amortization	497	342
Net	$ 284	$ 439

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Insurance	$ 22,941	$ 18,114
Payroll and employee benefits	8,747	10,028
Accrued rent	6,519	738
Interest	4,210	8,660
Percentage of completion adjustment	3,591	3,322
Income and other taxes	2,794	3,208
Accumulated deficit in joint venture		17,016
Other	7,416	7,957
Total accrued expenses	$ 56,218	$ 69,043

Long-Term Debt (Schedule Of Lon

Long-Term Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Revolving credit facility	$ 95,000	$ 104,111
Equipment notes payable	2,318	2,680
Notes payable	13,296	14,438
Line of credit, senior note payable, equipment notes payable and senior note	431,671	394,227
Current portion of equipment note payable	(1,546)	(1,320)
Current portion of note payable	(1,212)	(1,145)
Capital leases (included in other long term liabilities)	(772)	(1,360)
Long term debt	428,141	390,402
8.000% Senior Notes Due in 2022 [Member]
Debt Instrument [Line Items]
Senior notes	$ 321,057
7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Senior notes		$ 272,998

Long-Term Debt (Schedule Of L63

Long-Term Debt (Schedule Of Long-Term Debt) (Parenthetical) (Details)	Dec. 31, 2017	Dec. 31, 2016
8.000% Senior Notes Due in 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.00%
7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	7.375%	7.375%

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($)	Dec. 30, 2016	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018
Debt Instrument [Line Items]
Maximum availability of earnings under credit agreement for five consecutive days			$ 31,250,000
Maximum availability of earnings under credit agreement for one day			25,000,000
Revolving credit facility			95,000,000
Letters of credit outstanding			34,290,000
Letter of credit remaining borrowing capacity			76,819,000
Net proceeds from issuance			326,241,000		$ 3,050,000
Purchases of property and equipment			68,229,000	$ 83,798,000	74,455,000
Amortization of deferred financing fees			$ 3,280,000	$ 2,438,000	$ 1,729,000
Senior Notes [Member]
Debt Instrument [Line Items]
Face value of senior notes issued, percentage			100.00%
Net proceeds from issuance			$ 321,653,000
Vessels and Ancillary Equipment [Member]
Debt Instrument [Line Items]
Purchases of property and equipment		$ 15,569,000
Operating leases expiration year			2,023
8.000% Senior Notes Due in 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 325,000,000
Debt instrument, interest rate, stated percentage			8.00%
Maturity date			May 15, 2022
7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 275,000,000
Debt instrument, interest rate, stated percentage			7.375%	7.375%
Maturity date			Feb. 28, 2019
Redemption of notes			$ 282,638,000
5.75% Senior Notes Due In 2023 [Member] | Vessels and Ancillary Equipment [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		5.75%
Maximum [Member]
Debt Instrument [Line Items]
Expenses related to buy-out operating leases			20,000,000
Capital expenditures by credit parties			$ 75,000,000
Fixed charge coverage ratio	1.10%
Maximum [Member] | Scenario Forecast [Member]
Debt Instrument [Line Items]
Capital expenditures by credit parties						$ 135,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000
Line of credit facility optional increase capacity	$ 100,000,000
Revolving credit facility, maturity date			Dec. 30, 2019
Revolving Credit Facility [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%
Revolving Credit Facility [Member] | LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	3.00%
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Unused fee percentage	0.375%
Revolving Credit Facility [Member] | Maximum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%
Revolving Credit Facility [Member] | Maximum [Member] | LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	3.00%
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Unused fee percentage	0.25%
Revolving Credit Facility [Member] | Minimum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.50%
Revolving Credit Facility [Member] | Minimum [Member] | LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.50%
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000
Swingline Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	25,000,000
Prior Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Repayments of lines of credit	$ 199,000,000
Prior Revolving Credit Agreement [Member] | Maximum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.50%
Prior Revolving Credit Agreement [Member] | Maximum [Member] | LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.50%
Prior Revolving Credit Agreement [Member] | Minimum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.50%
Prior Revolving Credit Agreement [Member] | Minimum [Member] | LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.50%
Prior Secured Term Loan Facility [Member]
Debt Instrument [Line Items]
Payment of secured term loan	$ 50,000,000
Term loan facility bore interest fixed rate	4.655%

Long-Term Debt (Maturities Of L

Long-Term Debt (Maturities Of Long-Term Debt) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Debt Disclosure [Abstract]
2,018	$ 1,212
2,019	96,502
2,020	1,816
2,021	1,922
2,022	327,035
Thereafter	4,843
Total	$ 433,330

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Fair Values Of Financial Instruments And Nonfinancial Assets And Liabilities Measured At The Reporting Date) (Details) - Fuel Hedge Contracts [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Net Asset (Liability)	$ 2,501	$ 2,293
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Net Asset (Liability)	$ 2,501	$ 2,293

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) gal in Millions	3 Months Ended	12 Months Ended			24 Months Ended
	Jun. 30, 2015USD ($)	Dec. 31, 2017USD ($)Contract$ / galgal	Dec. 31, 2016USD ($)Contract	Dec. 31, 2015USD ($)	Dec. 31, 2016USD ($)Contract
Derivatives Fair Value [Line Items]
Derivative underlying hedge percent		80.00%
Derivative, Nonmonetary Notional Amount, Volume | gal		9.8
Fair value hedge assets		$ 2,501,000	$ 2,293,000		$ 2,293,000
Reclassification of derivative losses to earnings-net of tax		218,000	$ (30,000)
Impairment of goodwill		0		$ 2,750,000	$ 2,750,000
8.000% Senior Notes Due in 2022 [Member]
Derivatives Fair Value [Line Items]
Debt instrument, face amount		$ 325,000,000
Stated interest rate		8.00%
Maturity date		May 15, 2022
8.000% Senior Notes Due in 2022 [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives Fair Value [Line Items]
Fair value of debt		$ 340,048,000
Terra Contracting Services [Member]
Derivatives Fair Value [Line Items]
Impairment of goodwill	$ 2,750,000
Minimum [Member]
Derivatives Fair Value [Line Items]
Fixed price range | $ / gal		1.53
Maximum [Member]
Derivatives Fair Value [Line Items]
Fixed price range | $ / gal		2.02
Foreign Exchange Contract [Member]
Derivatives Fair Value [Line Items]
Number of outstanding contracts | Contract		0	0		0

Fair Value Measurements (Sche68

Fair Value Measurements (Schedule Of Fair Value Of Fuel Hedge Contracts Balance Sheet Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Asset derivatives	$ 2,501	$ 2,293
Other Current Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Fuel Hedge Contracts [Member]
Derivatives Fair Value [Line Items]
Asset derivatives	$ 2,501	546
Other Current Assets [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Fuel Hedge Contracts [Member]
Derivatives Fair Value [Line Items]
Asset derivatives		$ 1,747

Fair Value Measurements (Sche69

Fair Value Measurements (Schedule Of Fair Value Measurements Of Goodwill Using Significant Unobservable Inputs) (Details) - USD ($) $ in Thousands	12 Months Ended		24 Months Ended
	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2016
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Impairment of goodwill	$ 0	$ (2,750)	$ (2,750)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at January 1,		86,326	$ 86,326
Impairment of goodwill		(2,750)
Balance at December 31, 2015		$ 83,576

Fair Value Measurements (Change

Fair Value Measurements (Changes In Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Cumulative translation adjustments—net of tax	[1]	$ (41)	$ 508	$ (1,249)
Reclassification of derivative (gains) losses to earnings—net of tax		(218)	30
Change in fair value of derivatives—net of tax		1,407	300
Net unrealized (gain) loss on derivatives—net of tax	[2]	1,189	330
Other comprehensive income (loss)—net of tax		$ 1,148	$ 838	$ (1,249)
[1]	Net of income tax (provision) benefit of $44, $(338) and $827 for the years ended December 31, 2017, 2016 and 2015, respectively.
[2]	Net of income tax benefit of $1,048 and $216 for the years ended December 31, 2017 and 2016, respectively.

Fair Value Measurements (Adjust

Fair Value Measurements (Adjustments Reclassified From Accumulated Balances Other Comprehensive Income (Loss) To Earnings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments Gain Loss [Line Items]
Costs of contract revenues	$ 652,620	$ 681,197	$ 760,955
Income tax benefit	35,610	5,792	2,497
Net income (loss)	31,260	8,177	$ 6,189
Fuel Hedge Contracts [Member] | Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges | Reclassification Out Of Accumulated Other Comprehensive Income
Derivative Instruments Gain Loss [Line Items]
Costs of contract revenues	(358)	50
Income tax benefit	140	20
Net income (loss)	$ (218)	$ 30

Income Taxes (Income tax Benefi

Income Taxes (Income tax Benefit from Continuing and Discontinuing Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAX BENEFIT	$ 35,610	$ 5,792	$ 2,497
Income tax benefit from discontinued operations	8,203
Income tax benefit	$ 43,813

Income Taxes (Loss From Continu

Income Taxes (Loss From Continuing Operations Before Income Tax From Domestic And Foreign Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic operations	$ (17,307)	$ (2,295)	$ (35,996)
Foreign operations	(36,866)	(11,674)	27,310
Total loss from continuing operations before income tax	$ (54,173)	$ (13,969)	$ (8,686)

Income Taxes (Benefit For Incom

Income Taxes (Benefit For Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Current federal tax expense (benefit)	$ (248)	$ 260
Deferred federal tax expense (benefit)	(33,592)	(5,098)	$ (2,355)
Current state tax expense (benefit)	29	54	115
Deferred state tax expense (benefit)	(1,812)	(1,153)	(673)
Current foreign tax expense (benefit)	13	146	416
Income tax provision (benefit)	$ (35,610)	$ (5,791)	$ (2,497)

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
U.S. federal statutory income tax rate		35.00%	35.00%	35.00%
Reduction in net deferred tax liabilities		$ 15,720,000
Increase in valuation allowance		1,152,000	$ 1,031,000	$ 270,000
Operating loss carryforwards, subject to expiration		2,898,000
Operating loss carryforwards, subject to carry forward indefinitely		4,739,000
Unrecognized tax benefits		157,000	157,000	$ 157,000	$ 442,000
Amount of unrecognized tax benefits which would have an impact on the effective tax rate		124,000	124,000
Interest and penalties recorded		53,000	37,000
Deferred tax assets valuation allowance		4,294,000	7,133,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards for federal income tax purposes		207,875,000	51,158,000
Deferred tax assets valuation allowance		$ 0	0
Domestic Tax Authority [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year		2,034
Domestic Tax Authority [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year		2,037
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards for federal income tax purposes		$ 209,877,000	128,066,000
Valuation allowance for net operating loss carryforwards		$ 767,000
State and Local Jurisdiction [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year		2,023
State and Local Jurisdiction [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year		2,037
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards for federal income tax purposes		$ 7,637,000	12,165,000
Valuation allowance for net operating loss carryforwards		$ 1,962,000	$ 3,795,000
Foreign Tax Authority [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year		2,018
Foreign Tax Authority [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year		2,028
Scenario Forecast [Member]
Operating Loss Carryforwards [Line Items]
U.S. federal statutory income tax rate	21.00%

Income Taxes (Income Tax Bene76

Income Taxes (Income Tax Benefit Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax benefit at statutory U.S. federal income tax rate	$ (18,958)	$ (4,889)	$ (3,040)
State income tax — net of federal income tax benefit	(2,488)	(1,118)	(676)
Impact of Tax Cuts and Job Act	(15,720)
Charitable contributions			(469)
Adjustment to deferred tax depreciation			1,135
Change in deferred state tax rate		(1,082)
Research and development tax credits	(170)	(253)	(286)
Purchase price adjustment			393
Changes in unrecognized tax benefits	10	10	(186)
Changes in valuation allowance	1,152	1,031	270
Other	564	510	362
Income tax provision (benefit)	$ (35,610)	$ (5,791)	$ (2,497)

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits — January 1	$ 157	$ 157	$ 442
Gross increases — tax positions in prior period
Gross decreases — tax positions in prior period			(285)
Unrecognized tax benefits — December 31,	$ 157	$ 157	$ 157

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Accrued liabilities	$ 8,119	$ 16,194
Federal NOLs	43,654	17,905
Foreign NOLs	1,962	3,795
State NOLs	12,382	5,989
Tax credit carryforwards	1,941	5,970
Charitable contribution	1,340	1,883
Valuation allowance	(4,294)	(7,133)
Total deferred tax assets	65,104	44,603
Depreciation and amortization	(89,966)	(111,793)
Other liabilities	(699)	(1,259)
Total deferred tax liabilities	(90,665)	(113,052)
Net noncurrent deferred tax liabilities	$ (25,561)	$ (68,449)

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 2,963	$ 2,455	$ 4,040
Total unrecognized compensation cost related to non-vested RSUs	3,171
Amount related to shares used for tax withholding obligations	$ 328	$ 171
Annual retainer per non-employee director, percentage paid in cash	50.00%
Annual retainer per non-employee director, percentage paid in common stock	50.00%
Shares of common stock received by employee directors	207,000	86,000	112,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights	RSUs can either vest in equal portions over the three year vesting period or vest in one installment on the third anniversary of the grant date.
Vesting period	3 years
Total unrecognized compensation cost, weighted-average period of recognition	1 year 10 months 24 days
Non Qualified Stock Options (NQSO) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights	The option awards generally vest in three equal annual installments commencing on the first anniversary of the grant date
Exercise period	10 years
Awards granted in period	0	0	0
Employees And Directors [Member] | 2017 Long-Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	3,300,000
Employees And Directors [Member] | 2007 Long-Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Underlying equity awards issued	1,700,000
Non-Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual retainer per non-employee director	$ 155
Chairman of the Board [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional annual retainer paid to non-employee director	$ 150
Additional percentage of annual retainer paid to non-employee director in common stock	100.00%

Share-Based Compensation (Summa

Share-Based Compensation (Summary Of Stock Option Activity) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding as of January 1, 2017 | shares	1,699
Exercised | shares	(4)
Forfeited or Expired | shares	(318)
Outstanding as of December 31, 2017 | shares	1,377
Vested at December 31, 2017 | shares	1,377
Weighted average exercise price outstanding as of January 1, 2017 | $ / shares	$ 6.32
Weighted average exercise price, exercised | $ / shares	3.82
Weighted average exercise price, forfeited or expired | $ / shares	6.26
Weighted average exercise price outstanding as of December 31, 2017 | $ / shares	6.34
Weighted average exercise price, vested at December 31, 2017 | $ / shares	$ 6.34
Weighted average remaining contractual term, outstanding at December 31, 2017	3 years 4 months 24 days
Weighted average remaining contractual term, vested as of December 31, 2017	3 years 4 months 24 days
Aggregate intrinsic value, outstanding as of December 31, 2017 | $	$ 195
Aggregate intrinsic value, vested at December 31, 2017 | $	$ 195

Share-Based Compensation (Sum81

Share-Based Compensation (Summary Of Non-Vested Restricted Stock Units) (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding as of January 1, 2017 | shares	2,532
Options granted | shares	1,018
Options vested | shares	(222)
Options forfeited | shares	(1,132)
Options outstanding as of December 31, 2017 | shares	2,196
Options expected to vest at December 31, 2017 | shares	1,430
Weighted-average grant-date fair value as of January 1, 2017 | $ / shares	$ 5.23
Weighted-average grant-date fair value, granted | $ / shares	4.42
Weighted-average grant-date fair value, vested | $ / shares	5.66
Weighted-average grant-date fair value, forfeited | $ / shares	5.72
Weighted-average grant-date fair value as of December 31, 2017 | $ / shares	5.06
Weighted-average grant-date fair value, expected to vest at December 31, 2017 | $ / shares	$ 4.60

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Defined Contribution Plan Disclosure [Line Items]
Number of sponsored 401(k) plans | item	4
Expense for matching and discretionary contributions	$ 6,236	$ 3,705	$ 6,772
Contributes to various multiemployer pension plans	$ 5,639	$ 6,298	$ 4,990
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Multiemployer plans collective-bargaining arrangement percentage of contributions	5.00%

Retirement Plans (Schedule of S

Retirement Plans (Schedule of Significant Multiemployer Pension Plans) (Details) - Seafarers Pension Trust [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Multiemployer Plans [Line Items]
Federal Identification Number	136,100,329
Multiemployer Plan Number	1
Pension Protection Act of 2006 Certified Zone Status	Green	Green
Expiration of Collective Bargaining Arrangement with the Company	Feb. 28, 2018
Company's Contributions	$ 1,182	$ 1,102	$ 1,005

Restructuring Charges (Narrativ

Restructuring Charges (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Restructuring Cost And Reserve [Line Items]
Accrued rent expense	$ 5,930
Severance expense	1,567
Minimum [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	42,000
Restructuring charge related to non-cash	38,000
Minimum [Member] | Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge related to non-cash	12,500
Minimum [Member] | Loss on Sale of Assets [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge related to non-cash	3,000
Minimum [Member] | Other Items [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge related to non-cash	21,500
Maximum [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	47,000
Restructuring charge related to non-cash	43,000
Maximum [Member] | Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge related to non-cash	14,500
Maximum [Member] | Loss on Sale of Assets [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge related to non-cash	5,000
Maximum [Member] | Other Items [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge related to non-cash	23,500
Severance [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	3,000
Asset Retirements [Member] | Minimum [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	30,000
Asset Retirements [Member] | Maximum [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	34,000
Pre-contract Costs [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	6,500
Closeout Costs [Member] | Minimum [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	2,500
Closeout Costs [Member] | Maximum [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charge	$ 3,500

Restructuring Charges (Schedule

Restructuring Charges (Schedule of Restructuring Charges) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 29,485
Costs of Contract Revenues - Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	6,859
Costs of Contract Revenues - Other [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	16,109
General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	1,826
Loss on Sale of Assets—Net [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	4,691
Dredging [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	28,841
Dredging [Member] | Costs of Contract Revenues - Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	6,859
Dredging [Member] | Costs of Contract Revenues - Other [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	16,102
Dredging [Member] | General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	1,189
Dredging [Member] | Loss on Sale of Assets—Net [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	4,691
Environmental And Infrastructure [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	644
Environmental And Infrastructure [Member] | Costs of Contract Revenues - Other [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	7
Environmental And Infrastructure [Member] | General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 637

Commitments And Contingencies86

Commitments And Contingencies (Narrative) (Details) - USD ($)	Feb. 28, 2017	Jan. 14, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2017
Commitments And Contingencies [Line Items]
Outstanding performance bonds			$ 1,340,846,000
Revenue value remaining from outstanding performance bonds			515,332,000
Proceeds from Legal Settlements		$ 5,309,000
Rent expense under long term operating lease arrangements			27,218,000	$ 21,061,000	$ 21,697,000
Surety Bond [Member]
Commitments And Contingencies [Line Items]
Aggregate demolition surety performance bond	$ 20,000,000
Letter of Credit [Member]
Commitments And Contingencies [Line Items]
Line of credit facility, maximum borrowing capacity						$ 20,881,000
Environmental And Infrastructure Segment [Member]
Commitments And Contingencies [Line Items]
Outstanding performance bonds			41,085,000
Minimum [Member]
Commitments And Contingencies [Line Items]
Bids bond range			$ 1,000,000
Warranty periods			1 year
Maximum [Member]
Commitments And Contingencies [Line Items]
Bids bond range			$ 10,000,000
Warranty periods			3 years

Commitments And Contingencies87

Commitments And Contingencies (Future Minimum Operating Lease Payments) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,018	$ 21,310
2,019	17,119
2,020	14,365
2,021	12,500
2,022	8,773
Thereafter	8,408
Total minimum operating lease payments	$ 82,475

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Equity Method Investments [Line Items]
Other current assets	$ 40,228	$ 63,412
Accumulated deficit in joint ventures		17,016
Amboy Aggregates [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership percentage	50.00%
TerraSea Environmental Solutions [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Other current assets		24,696
Accumulated deficit in joint ventures		$ 17,016
Loss from joint venture	$ 1,458

Investment (Summary Financial I

Investment (Summary Financial Information Under Equity Method) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amboy Aggregates [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Revenue			$ 139
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss)		$ 758	(1,363)
Equity Method Investment, Summarized Financial Information, Income (Loss) from Continuing Operations before Extraordinary Items	$ 34	758	(3,152)
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$ 34	758	(3,152)
TerraSea Environmental Solutions [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Revenue			6,960
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss)		(183)	(3,800)
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		$ (183)	$ (3,800)

Related Party Transactions (Det

Related Party Transactions (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2017Property	Dec. 31, 2017USD ($)Facility	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Related Party Transaction [Line Items]
Rent expense		$ 27,218	$ 21,061	$ 21,697
Number of properties sold to a non-related party | Property	1
Terra Contracting LLC [Member]
Related Party Transaction [Line Items]
Rent expense			195	243
Number of facilities owned by former owner | Facility		2
Great Lakes Environmental & Infrastructure, LLC [Member]
Related Party Transaction [Line Items]
Lease termination date		Nov. 11, 2016
Magnus Pacific Corporation [Member]
Related Party Transaction [Line Items]
Rent expense		$ 263	$ 506	$ 402
Number of facilities owned by former owner | Facility		2

Business Combinations And Dis91

Business Combinations And Dispositions (Narrative) (Details) - USD ($)	Feb. 28, 2017	Nov. 04, 2014	Apr. 23, 2014	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Estimated surety bond claim, including associated expenses					$ 20,900,000
(GAIN) LOSS ON SALE OF ASSETS—Net					$ 5,077,000	$ 6,175,000	$ (855,000)
Environmental And Infrastructure Segment [Member]
Business Acquisition [Line Items]
(GAIN) LOSS ON SALE OF ASSETS—Net						$ 2,758,000
Great Lakes Environmental & Infrastructure, LLC [Member]
Business Acquisition [Line Items]
Fair value of debt				$ 0
Adjustment to fair value of debt				$ 8,940,000
Magnus Pacific Acquisition [Member]
Business Acquisition [Line Items]
Base purchase price		$ 40,000,000
Payments for previous acquisition		25,000,000
Fair value of debt							$ 0
Maximum potential aggregate earnout payment		$ 11,400,000
Surety Bond [Member]
Business Acquisition [Line Items]
Aggregate demolition surety performance bond	$ 20,000,000
NASDI, LLC and Yankee Environmental Services, LLC
Business Acquisition [Line Items]
Proceeds from divestiture of businesses			$ 5,309,000

Business Combinations And Dis92

Business Combinations And Dispositions - (Schedule Of Discontinued Operations) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Business Combinations [Abstract]
Loss before income taxes from discontinued operations	$ (20,900)
Income tax benefit	8,203
Loss from discontinued operations, net of income taxes	$ (12,697)

Segment Information (Narrative)

Segment Information (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Long-lived assets, net book value	$ 47,563	$ 63,729
Landfill [Member]
Segment Reporting Information [Line Items]
Loss on sale of project			$ (7,446)
Dredging [Member] | Sales [Member] | Geographic Concentration Risk [Member] | Middle East [Member]
Segment Reporting Information [Line Items]
Concentration risk percentage			14.70%
Dredging [Member] | Sales [Member] | Geographic Concentration Risk [Member] | Middle East [Member] | Maximum [Member]
Segment Reporting Information [Line Items]
Concentration risk percentage	10.00%	10.00%
Dredging [Member] | Sales [Member] | Federal Government Agencies [Member] | Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Concentration risk percentage	53.60%	53.40%	51.00%
Dredging [Member] | Accounts Receivable [Member] | Geographic Concentration Risk [Member] | Middle East [Member]
Segment Reporting Information [Line Items]
Concentration risk percentage		13.00%
Dredging [Member] | Accounts Receivable [Member] | Geographic Concentration Risk [Member] | Middle East [Member] | Maximum [Member]
Segment Reporting Information [Line Items]
Concentration risk percentage	10.00%
Dredging [Member] | Accounts Receivable [Member] | Federal Government Agencies [Member] | Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Concentration risk percentage	34.70%	39.90%
Remediation Project [Member]
Segment Reporting Information [Line Items]
Loss on sale of project		$ (5,934)	$ (7,260)

Segment Information (Segment Re

Segment Information (Segment Reporting By Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Contract revenues	$ 702,503	$ 767,585	$ 856,878
Operating income (loss)	(23,525)	14,680	22,959
Depreciation and amortization	60,520	63,023	64,585
Total assets	832,357	893,588	898,124
PROPERTY AND EQUIPMENT—Net	407,294	413,008	430,210
GOODWILL	83,576	83,576	83,576	$ 86,326
INVESTMENTS IN JOINT VENTURES	2,714	4,734	3,761
Capital expenditures	66,068	85,212	89,279
Dredging Segment [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	(13,353)	34,108	64,073
Depreciation and amortization	55,962	54,826	50,556
Total assets	878,458	912,880	872,297
PROPERTY AND EQUIPMENT—Net	396,925	399,479	397,468
GOODWILL	76,576	76,576	76,576	$ 76,576
INVESTMENTS IN JOINT VENTURES		381	1
Capital expenditures	63,912	84,263	82,000
Environmental And Infrastructure Segment [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	(10,172)	(19,428)	(41,114)
Depreciation and amortization	4,558	8,197	14,029
Total assets	78,806	81,166	127,907
PROPERTY AND EQUIPMENT—Net	10,369	13,529	32,742
GOODWILL	7,000	7,000	7,000
INVESTMENTS IN JOINT VENTURES	2,714	4,353	3,760
Capital expenditures	2,156	949	7,279
Operating Segment [Member] | Dredging Segment [Member]
Segment Reporting Information [Line Items]
Contract revenues	592,159	637,468	681,255
Operating Segment [Member] | Environmental And Infrastructure Segment [Member]
Segment Reporting Information [Line Items]
Contract revenues	112,607	133,637	181,710
Intersegment Revenue [Member]
Segment Reporting Information [Line Items]
Contract revenues	(2,263)	(3,520)	(6,087)
Total assets	$ (124,907)	$ (100,458)	$ (102,080)

Segment Information (Dredging R

Segment Information (Dredging Revenue By Type Of Work) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	$ 702,503	$ 767,585	$ 856,878
Dredging [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	592,159	637,468	681,255
Dredging [Member] | Capital Dredging - U.S. [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	185,113	219,914	207,058
Dredging [Member] | Capital dredging - Foreign [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	42,306	59,413	139,945
Dredging [Member] | Beach Nourishment Dredging [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	191,070	215,041	184,060
Dredging [Member] | Maintenance Dredging [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	134,923	92,274	120,055
Dredging [Member] | Rivers & Lakes [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue as reported	$ 38,747	$ 50,826	$ 30,137

Segment Information (Revenues A

Segment Information (Revenues And Gross Profit From Foreign Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues From External Customers And Long Lived Assets [Line Items]
Contract revenues	$ 702,503	$ 767,585	$ 856,878
Costs of contract revenues	(652,620)	(681,197)	(760,955)
GROSS PROFIT	49,883	86,388	95,923
Foreign [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Contract revenues	42,306	59,413	139,945
Costs of contract revenues	(73,958)	(66,729)	(105,951)
GROSS PROFIT	$ (31,652)	$ (7,316)	$ 33,994

Subsidiary Guarantors (Narrativ

Subsidiary Guarantors (Narrative) (Details) - 8% SENIOR NOTES [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Condensed Financial Statements, Captions [Line Items]
SENIOR NOTES	$ 325,000
Debt instrument, interest rate, stated percentage	8.00%
Maturity date	May 15, 2022
Owned Domestic Subsidiaries Percent	100.00%

Subsidiary Guarantors (Condense

Subsidiary Guarantors (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CURRENT ASSETS:
Cash and cash equivalents	$ 15,852	$ 11,167	$ 14,184	$ 42,389
Accounts receivable—net	75,533	88,091
Contract revenues in excess of billings	90,788	95,012
Inventories	34,600	37,137
Prepaid expenses	5,183	12,407
Other current assets	40,228	63,412
Total current assets	262,184	307,226
PROPERTY AND EQUIPMENT—Net	407,294	413,008	430,210
GOODWILL	83,576	83,576	83,576	86,326
OTHER INTANGIBLE ASSETS — Net	908	1,499
INVENTORIES—Noncurrent	54,023	52,602
INVESTMENTS IN JOINT VENTURES	2,714	4,734	3,761
ASSETS HELD FOR SALE— Noncurrent	8,530	9,299
OTHER	13,128	21,644
TOTAL	832,357	893,588	898,124
LIABILITIES AND EQUITY
Accounts payable	87,659	103,185
Accrued expenses	56,218	69,043
Billings in excess of contract revenues	3,615	5,141
Current portion of long-term debt	2,758	2,465
Total current liabilities	150,250	179,834
LONG-TERM DEBT	333,141	286,291
REVOLVING CREDIT FACILITY	95,000	104,111
DEFERRED INCOME TAXES	25,561	68,449
OTHER	7,109	7,013
Total liabilities	611,061	645,698
TOTAL EQUITY	221,296	247,890	252,173	255,963
TOTAL	832,357	893,588
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
CURRENT ASSETS:
Cash and cash equivalents	15,794	10,414	11,698	44,636
Accounts receivable—net	75,431	75,412
Contract revenues in excess of billings	90,788	91,478
Inventories	34,600	37,137
Prepaid expenses	5,183	12,287
Other current assets	38,731	60,844
Total current assets	260,527	287,572
PROPERTY AND EQUIPMENT—Net	407,293	407,516
GOODWILL	83,576	83,576
OTHER INTANGIBLE ASSETS — Net	571	1,067
INVENTORIES—Noncurrent	54,023	52,602
INVESTMENTS IN JOINT VENTURES	2,555	4,685
ASSETS HELD FOR SALE— Noncurrent	8,530	8,390
RECEIVABLES FROM AFFILIATES	45,375	58,284
OTHER	7,971	14,692
TOTAL	870,421	918,384
LIABILITIES AND EQUITY
Accounts payable	87,379	101,795
Accrued expenses	50,382	55,940
Billings in excess of contract revenues	3,615	4,699
Current portion of long-term debt	1,546	305
Total current liabilities	142,922	162,739
DEFERRED INCOME TAXES		(1,833)
PAYABLES TO AFFILIATES	161,979	80,769
INVESTMENTS IN SUBSIDIARIES	41,358	32,000
OTHER	6,940	5,925
Total liabilities	353,199	279,600
TOTAL EQUITY	517,222	638,784
TOTAL	870,421	918,384
Reportable Legal Entities [Member] | Non Guarantor Subsidiaries [Member]
CURRENT ASSETS:
Cash and cash equivalents	38	751	2,484	(2,249)
Accounts receivable—net	102	14,242
Contract revenues in excess of billings		3,534
Prepaid expenses		120
Other current assets	1,497	2,568
Total current assets	1,637	21,215
PROPERTY AND EQUIPMENT—Net	1	5,492
OTHER INTANGIBLE ASSETS — Net	337	432
INVESTMENTS IN JOINT VENTURES	159	49
ASSETS HELD FOR SALE— Noncurrent		909
RECEIVABLES FROM AFFILIATES	6,754	16,807
OTHER	1	1
TOTAL	8,889	44,905
LIABILITIES AND EQUITY
Accounts payable	280	2,879
Accrued expenses	1,312	3,222
Billings in excess of contract revenues		499
Current portion of long-term debt		1,015
Total current liabilities	1,592	7,615
PAYABLES TO AFFILIATES	54,442	70,921
OTHER		937
Total liabilities	56,034	79,473
TOTAL EQUITY	(47,145)	(34,568)
TOTAL	8,889	44,905
Reportable Legal Entities [Member] | GLDD Corporation [Member]
CURRENT ASSETS:
Cash and cash equivalents	20	2	$ 2	$ 2
Total current assets	20	2
RECEIVABLES FROM AFFILIATES	170,323	82,340
INVESTMENTS IN SUBSIDIARIES	511,435	636,216
OTHER	5,156	6,951
TOTAL	686,934	725,509
LIABILITIES AND EQUITY
Accounts payable		17
Accrued expenses	4,524	9,881
Current portion of long-term debt	1,212	1,145
Total current liabilities	5,736	11,043
LONG-TERM DEBT	333,141	286,291
REVOLVING CREDIT FACILITY	95,000	104,111
DEFERRED INCOME TAXES	25,561	70,282
PAYABLES TO AFFILIATES	6,031	5,741
OTHER	169	151
Total liabilities	465,638	477,619
TOTAL EQUITY	221,296	247,890
TOTAL	686,934	725,509
Consolidation Eliminations [Member]
CURRENT ASSETS:
Accounts receivable—net		(1,563)
Total current assets		(1,563)
RECEIVABLES FROM AFFILIATES	(222,452)	(157,431)
INVESTMENTS IN SUBSIDIARIES	(511,435)	(636,216)
TOTAL	(733,887)	(795,210)
LIABILITIES AND EQUITY
Accounts payable		(1,506)
Billings in excess of contract revenues		(57)
Total current liabilities		(1,563)
PAYABLES TO AFFILIATES	(222,452)	(157,431)
INVESTMENTS IN SUBSIDIARIES	(41,358)	(32,000)
Total liabilities	(263,810)	(190,994)
TOTAL EQUITY	(470,077)	(604,216)
TOTAL	$ (733,887)	$ (795,210)

Subsidiary Guarantors (Conden99

Subsidiary Guarantors (Condensed Consolidating Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended			24 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Contract revenues	$ 702,503	$ 767,585	$ 856,878
Costs of contract revenues	(652,620)	(681,197)	(760,955)
GROSS PROFIT	49,883	86,388	95,923
General and administrative expenses	68,331	65,533	71,069
Impairment of goodwill	0		2,750	$ 2,750
(GAIN) LOSS ON SALE OF ASSETS—Net	5,077	6,175	(855)
Total operating income (loss)	(23,525)	14,680	22,959
Interest income (expense)—net	(26,046)	(22,907)	(24,365)
Equity in earnings (loss) of joint ventures	(1,484)	(2,365)	(6,051)
Loss on extinguishment of debt	(2,330)
Other income (expense)	(788)	(3,377)	(1,229)
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(54,173)	(13,969)	(8,686)
Income tax benefit	35,610	5,792	2,497
LOSS FROM CONTINUING OPERATIONS	(18,563)	(8,177)	(6,189)
Loss from discontinued operations, net of income taxes	(12,697)
NET LOSS	(31,260)	(8,177)	(6,189)
Comprehensive loss	(30,112)	(7,339)	(7,438)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Contract revenues	699,607	726,239	778,337
Costs of contract revenues	(647,467)	(622,158)	(670,973)
GROSS PROFIT	52,140	104,081	107,364
General and administrative expenses	67,175	51,678	58,682
(GAIN) LOSS ON SALE OF ASSETS—Net	4,801	3,040	(885)
Total operating income (loss)	(19,836)	49,363	49,567
Interest income (expense)—net	1,054	1,985	872
Equity in earnings (loss) of subsidiaries	38	(31,488)	34
Equity in earnings (loss) of joint ventures	(1,484)	(2,365)	(6,221)
Other income (expense)	(1,240)	(2,626)	(3,180)
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(21,468)	14,869	41,072
Income tax benefit	(1,250)	1,080	1,641
LOSS FROM CONTINUING OPERATIONS	(22,718)
Loss from discontinued operations, net of income taxes	(20,900)
NET LOSS	(43,618)	15,949	42,713
Comprehensive loss	(42,429)	16,279	42,713
Reportable Legal Entities [Member] | Non Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Contract revenues	5,163	44,086	86,666
Costs of contract revenues	(7,420)	(61,779)	(98,107)
GROSS PROFIT	(2,257)	(17,693)	(11,441)
General and administrative expenses	1,156	13,904	12,387
Impairment of goodwill			2,750
(GAIN) LOSS ON SALE OF ASSETS—Net	276	3,135	30
Total operating income (loss)	(3,689)	(34,732)	(26,608)
Interest income (expense)—net	(966)	(1,497)	(1,398)
Equity in earnings (loss) of joint ventures			170
Other income (expense)	452	(751)	1,951
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(4,203)	(36,980)	(25,885)
Income tax benefit	(14)	(144)	(512)
LOSS FROM CONTINUING OPERATIONS	(4,217)
NET LOSS	(4,217)	(37,124)	(26,397)
Comprehensive loss	(4,258)	(36,616)	(27,646)
Reportable Legal Entities [Member] | GLDD Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
General and administrative expenses		(49)
Total operating income (loss)		49
Interest income (expense)—net	(26,134)	(23,395)	(23,839)
Equity in earnings (loss) of subsidiaries	(26,973)	10,313	16,282
Loss on extinguishment of debt	(2,330)
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(55,437)	(13,033)	(7,557)
Income tax benefit	36,874	4,856	1,368
LOSS FROM CONTINUING OPERATIONS	(18,563)
Loss from discontinued operations, net of income taxes	(12,697)
NET LOSS	(31,260)	(8,177)	(6,189)
Comprehensive loss	(30,112)	(7,339)	(7,438)
Consolidation Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Contract revenues	(2,267)	(2,740)	(8,125)
Costs of contract revenues	2,267	2,740	8,125
Equity in earnings (loss) of subsidiaries	26,935	21,175	(16,316)
LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	26,935	21,175	(16,316)
LOSS FROM CONTINUING OPERATIONS	26,935
Loss from discontinued operations, net of income taxes	20,900
NET LOSS	47,835	21,175	(16,316)
Comprehensive loss	$ 46,687	$ 20,337	$ (15,067)

Subsidiary Guarantors (Conde100

Subsidiary Guarantors (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES:
Net cash flows provided by operating activities of continuing operations	$ 42,418	$ 38,670	$ 29,122
Net cash flows used in operating activities of discontinued operations	(20,900)
Cash provided by operating activities	21,518	38,670	29,122
INVESTING ACTIVITIES:
Purchases of property and equipment	(68,229)	(83,798)	(74,455)
Proceeds from dispositions of property and equipment	10,077	18,257	1,322
Changes in restricted cash	7,035	(7,035)
Cash used in investing activities	(51,117)	(72,576)	(73,133)
FINANCING ACTIVITIES:
Proceeds from issuance of debt	326,241		3,050
Repayments of debt	(277,750)	(47,085)	(6,644)
7 3/8% senior notes tender premium	(744)
Deferred financing fees	(5,022)	(6,817)	(111)
Taxes paid on settlement of vested share awards	(328)	(171)	(267)
Exercise of stock options and purchases from employee stock plans	883	905	1,365
Excess income tax benefit from share-based compensation		(133)	(57)
Purchase of treasury stock			(1,433)
Borrowings under revolving loans	124,925	288,611	179,500
Repayments of revolving loans	(134,036)	(204,500)	(159,500)
Cash provided by financing activities	34,169	30,810	15,903
Effect of foreign currency exchange rates on cash and cash equivalents	115	79	(97)
Net increase (decrease) in cash and cash equivalents	4,685	(3,017)	(28,205)
Cash and cash equivalents at beginning of period	11,167	14,184	42,389
Cash and cash equivalents at end of period	15,852	11,167	14,184
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash flows provided by operating activities of continuing operations	64,610
Net cash flows used in operating activities of discontinued operations	(20,900)
Cash provided by operating activities	43,710	74,409	75,489
INVESTING ACTIVITIES:
Purchases of property and equipment	(75,940)	(83,777)	(70,759)
Proceeds from dispositions of property and equipment	8,620	10,582	1,102
Changes in restricted cash	7,035	(7,035)
Net change in accounts with affiliates	3,732	(5,100)	(32,342)
Cash used in investing activities	(56,553)	(85,330)	(101,999)
FINANCING ACTIVITIES:
Proceeds from issuance of debt	1,241
Repayments of debt	(1,602)	(296)	(195)
Net change in accounts with affiliates	90,153	32,933	(23,491)
Transfer (to) from parent	(71,569)	(23,000)	17,258
Cash provided by financing activities	18,223	9,637	(6,428)
Net increase (decrease) in cash and cash equivalents	5,380	(1,284)	(32,938)
Cash and cash equivalents at beginning of period	10,414	11,698	44,636
Cash and cash equivalents at end of period	15,794	10,414	11,698
Reportable Legal Entities [Member] | Non Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash flows provided by operating activities of continuing operations	4,910
Cash provided by operating activities	4,910	(16,677)	(22,679)
INVESTING ACTIVITIES:
Purchases of property and equipment	7,711	(21)	(3,696)
Proceeds from dispositions of property and equipment	1,457	7,675	220
Transfer to parent	(9,615)
Cash used in investing activities	(447)	7,654	(3,476)
FINANCING ACTIVITIES:
Repayments of debt		(1,128)	(1,006)
Net change in accounts with affiliates	(5,291)	8,339	31,991
Cash provided by financing activities	(5,291)	7,211	30,985
Effect of foreign currency exchange rates on cash and cash equivalents	115	79	(97)
Net increase (decrease) in cash and cash equivalents	(713)	(1,733)	4,733
Cash and cash equivalents at beginning of period	751	2,484	(2,249)
Cash and cash equivalents at end of period	38	751	2,484
Reportable Legal Entities [Member] | GLDD Corporation [Member]
OPERATING ACTIVITIES:
Net cash flows provided by operating activities of continuing operations	(27,102)
Cash provided by operating activities	(27,102)	(19,062)	(23,688)
INVESTING ACTIVITIES:
Net change in accounts with affiliates	(88,594)	(36,172)	(12,222)
Transfer to parent	81,184	23,000
Cash used in investing activities	(7,410)	(13,172)	(12,222)
FINANCING ACTIVITIES:
Proceeds from issuance of debt	325,000		3,050
Repayments of debt	(276,148)	(45,661)	(5,443)
7 3/8% senior notes tender premium	(744)
Deferred financing fees	(5,022)	(6,817)	(111)
Taxes paid on settlement of vested share awards	(328)	(171)	(267)
Net change in accounts with affiliates			36,064
Transfer (to) from parent			(17,258)
Exercise of stock options and purchases from employee stock plans	883	905	1,365
Excess income tax benefit from share-based compensation		(133)	(57)
Purchase of treasury stock			(1,433)
Borrowings under revolving loans	124,925	288,611	179,500
Repayments of revolving loans	(134,036)	(204,500)	(159,500)
Cash provided by financing activities	34,530	32,234	35,910
Net increase (decrease) in cash and cash equivalents	18
Cash and cash equivalents at beginning of period	2	2	2
Cash and cash equivalents at end of period	20	2	2
Consolidation Eliminations [Member]
INVESTING ACTIVITIES:
Net change in accounts with affiliates	84,862	41,272	44,564
Transfer to parent	(71,569)	(23,000)
Cash used in investing activities	13,293	18,272	44,564
FINANCING ACTIVITIES:
Net change in accounts with affiliates	(84,862)	(41,272)	(44,564)
Transfer (to) from parent	71,569	23,000
Cash provided by financing activities	$ (13,293)	$ (18,272)	$ (44,564)

Subsidiary Guarantors (Conde101

Subsidiary Guarantors (Condensed Consolidating Statement of Cash Flows) (Parenthetical) (Details)	Dec. 31, 2017	Dec. 31, 2016
7 3/8% SENIOR NOTES [Member]
Debt instrument, interest rate, stated percentage	7.375%	7.375%

Schedule II-Valuation And Qu102

Schedule II-Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 7,880	$ 6,855	$ 7,157
Additions charged to costs and expenses	1,567	1,421	446
Deductions	(4,612)	(396)	(748)
Ending Balance	4,835	7,880	6,855
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	747	754	578
Additions charged to costs and expenses	415	389	176
Deductions	(621)	(396)
Ending Balance	541	747	754
Valuation Allowance for Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	7,133	6,101	6,579
Additions charged to costs and expenses	1,152	1,032	270
Deductions	(3,991)		(748)
Ending Balance	$ 4,294	$ 7,133	$ 6,101