Great Lakes Dredge & Dock (GLDD) 10-K 26 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 22, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
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 Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		62,645,515
Entity Public Float			$ 315,856,963
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, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 34,458	$ 15,852
Accounts receivable—net	64,779	51,940
Contract revenues in excess of billings	17,953	77,907
Inventories	28,112	34,432
Prepaid expenses	4,710	5,031
Other current assets	31,907	38,605
Assets held for sale	24,779	38,417
Total current assets	206,698	262,184
PROPERTY AND EQUIPMENT—Net	369,863	396,925
GOODWILL	76,576	76,576
INVENTORIES—Noncurrent	61,264	54,023
ASSETS HELD FOR SALE— Noncurrent	5,110	29,561
OTHER	10,760	13,088
TOTAL	730,271	832,357
LIABILITIES AND EQUITY
Accounts payable	71,537	65,153
Accrued expenses	48,351	51,926
Billings in excess of contract revenues	17,793	2,586
Revolving credit facility	11,500
Current portion of long-term debt		1,212
Liabilities held for sale	13,940	29,373
Total current liabilities	163,121	150,250
LONG-TERM DEBT	321,950	333,141
REVOLVING CREDIT FACILITY	11,500	95,000
DEFERRED INCOME TAXES	22,846	25,561
LIABILITIES HELD FOR SALE— Noncurrent	146	773
OTHER	7,280	6,336
Total liabilities	515,343	611,061
COMMITMENTS AND CONTINGENCIES (Note 12)
EQUITY:
Common stock—$.0001 par value; 90,000 authorized, 62,830 and 61,897 shares issued; 62,552 and 61,619 outstanding at December 31, 2018 and December 31, 2017, respectively.	6	6
Treasury stock, at cost	(1,433)	(1,433)
Additional paid-in capital	295,135	289,821
Accumulated deficit	(74,971)	(67,101)
Accumulated other comprehensive income (loss)	(3,809)	3
Total equity	214,928	221,296
TOTAL	$ 730,271	$ 832,357

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
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	62,830,000	61,897,000
Common stock, shares outstanding	62,552,000	61,619,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
CONTRACT REVENUES	$ 620,795	$ 592,159	$ 637,468
Type of Revenue [Extensible List]	gldd:ContractMember	gldd:ContractMember	gldd:ContractMember
COSTS OF CONTRACT REVENUES	$ 509,335	$ 549,429	$ 552,130
Type of Cost, Good or Service [Extensible List]	gldd:ContractMember	gldd:ContractMember	gldd:ContractMember
GROSS PROFIT	$ 111,460	$ 42,730	$ 85,338
OPERATING EXPENSES:
GENERAL AND ADMINISTRATIVE EXPENSES	55,108	57,235	55,271
LOSS ON SALE OF ASSETS—Net	3,731	4,789	3,089
Total operating income (loss)	52,621	(19,294)	26,978
OTHER EXPENSE:
Interest expense—net	(33,578)	(26,032)	(23,471)
Equity in loss of joint ventures		(1,484)	(2,365)
Loss on extinguishment of debt		(2,330)
Other income (expense)	(2,590)	11	(777)
Total other expense	(36,168)	(29,835)	(26,613)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	16,453	(49,129)	365
INCOME TAX (PROVISION) BENEFIT	(5,437)	33,761	177
INCOME (LOSS) FROM CONTINUING OPERATIONS	11,016	(15,368)	542
Loss from discontinued operations, net of income taxes	(17,309)	(15,892)	(8,719)
NET LOSS	$ (6,293)	$ (31,260)	$ (8,177)
Basic earnings (loss) per share attributable to income (loss) from continuing operations	$ 0.18	$ (0.25)	$ 0.01
Basic loss per share attributable to loss on discontinued operations, net of income taxes	(0.28)	(0.26)	(0.14)
Basic loss per share	$ (0.10)	$ (0.51)	$ (0.13)
Basic weighted average shares	62,236	61,365	60,744
Diluted earnings (loss) per share attributable to income (loss) from continuing operations	$ 0.17	$ (0.25)	$ 0.01
Diluted loss per share attributable to loss on discontinued operations, net of income taxes	(0.27)	(0.26)	(0.14)
Diluted loss per share	$ (0.10)	$ (0.51)	$ (0.13)
Diluted weighted average shares	63,607	61,365	61,367

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (6,293)	$ (31,260)	$ (8,177)
Currency translation adjustment—net of tax	[1]	1,513	(41)	508
Net unrealized (gain) loss on derivatives—net of tax	[2]	(5,325)	1,189	330
Other comprehensive income (loss)—net of tax		(3,812)	1,148	838
Comprehensive loss		$ (10,105)	$ (30,112)	$ (7,339)
[1]	Net of income tax (provision) benefit of (1,017), $44 and (338) for the years ended December 31, 2018, 2017 and 2016, respectively.
[2]	Net of income tax benefit of $775, $1,048 and $216 for the years ended December 31, 2018, 2017 and 2016, respectively.

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Currency translation adjustment, tax	$ (1,017)	$ 44	$ (338)
Net unrealized loss on derivatives, tax	$ 775	$ 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, 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 purchase plan, value	905			905
Exercise of stock options and purchases from employee stock purchase 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 purchase plan, value	883			883
Exercise of stock options and purchases from employee stock purchase plan, shares		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)
Cumulative effect of recent accounting pronouncements	(1,577)				(1,577)
Share-based compensation, value	5,425			5,425
Share-based compensation, shares		132
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(1,205)			(1,205)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		520
Exercise of stock options and purchases from employee stock purchase plan, value	$ 1,094			1,094
Exercise of stock options and purchases from employee stock purchase plan, shares	62	281
Net loss	$ (6,293)				(6,293)
Other comprehensive income (loss)—net of tax	(3,812)					(3,812)
BALANCE - value at Dec. 31, 2018	$ 214,928	$ 6	$ (1,433)	$ 295,135	$ (74,971)	$ (3,809)
BALANCE - shares at Dec. 31, 2018		62,830	(278)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net loss	$ (6,293)	$ (31,260)	$ (8,177)
Loss from discontinued operations, net of income taxes	(17,309)	(15,892)	(8,719)
Income (loss) from continuing operations	11,016	(15,368)	542
Adjustments to reconcile net loss to net cash flows provided by operating activities:
Depreciation and amortization	50,389	55,962	54,826
Equity in loss of joint ventures		1,484	2,365
Loss on extinguishment of 7 3/8% senior subordinated notes		2,330
Cash distributions from joint ventures		340
Deferred income taxes	5,760	(32,836)	(494)
Loss on dispositions of property and equipment	3,731	4,789	3,089
Other non-cash restructuring items	2,337	15,678
Amortization of deferred financing fees	3,504	3,280	2,439
Unrealized foreign currency (gain) loss	(231)	(206)	474
Unrealized net (gain) loss from mark-to-market valuations of derivatives		1,747	(6,135)
Share-based compensation expense	4,643	2,917	2,651
Excess income tax benefit from share-based compensation			133
Changes in assets and liabilities:
Accounts receivable	(8,364)	5,354	15,129
Contract revenues in excess of billings	54,881	10,939	(14,183)
Inventories	(921)	(2,163)	(6,239)
Prepaid expenses and other current assets	11,976	(1,868)	(6,583)
Accounts payable and accrued expenses	(1,480)	(16,179)	(8,813)
Billings in excess of contract revenues	7,524	(567)	(730)
Other noncurrent assets and liabilities	(3,093)	(1,658)	(3,751)
Net cash flows provided by operating activities of continuing operations	141,672	33,976	34,720
Net cash flows (used) provided in operating activities of discontinued operations	(4,019)	(12,457)	3,950
Cash provided by operating activities	137,653	21,518	38,670
INVESTING ACTIVITIES:
Purchases of property and equipment	(49,422)	(65,996)	(82,849)
Proceeds from dispositions of property and equipment	13,880	8,586	10,049
Net cash flows used in investing activities of continuing operations	(35,542)	(57,410)	(72,800)
Net cash flows (used) provided by investing activities of discontinued operations	425	(742)	7,259
Cash used in investing activities	(35,117)	(58,152)	(65,541)
FINANCING ACTIVITIES:
Proceeds from issuance of debt		325,000
Repayments of debt	(298)	(276,148)	(45,662)
7 3/8% senior notes tender premium		(744)
Deferred financing fees		(5,022)	(6,818)
Taxes paid on settlement of vested share awards	(1,205)	(328)	(171)
Exercise of stock options and purchases from employee stock plans	1,094	883	905
Excess income tax benefit from share-based compensation			(133)
Borrowings under revolving loans	29,000	124,925	288,611
Repayments of revolving loans	(112,500)	(134,036)	(204,500)
Net cash flows (used) provided in financing activities of continuing operations	(83,909)	34,530	32,232
Net cash flows used in financing activities of discontinued operations	(1,547)	(361)	(1,422)
Cash (used) provided in financing activities	(85,456)	34,169	30,810
Effect of foreign currency exchange rates on cash and cash equivalents	26	115	79
Net increase (decrease) in cash, cash equivalents and restricted cash	17,106	(2,350)	4,018
Cash, cash equivalents and restricted cash at beginning of period	17,352	19,702	15,684
Cash, cash equivalents and restricted cash at end of period	34,458	17,352	19,702
Cash and cash equivalents	34,458	15,852	11,167
Restricted cash included in other long-term assets		1,500	8,535
Cash, cash equivalents and restricted cash at end of period	34,458	17,352	19,702
Supplemental Cash Flow Information
Cash paid for interest	30,855	34,789	26,563
Cash paid for income taxes	290	365	200
Non-cash Investing and Financing Activities
Property and equipment purchased but not yet paid	7,303	$ 4,255	$ 8,795
Repayments of debt with proceeds from sale-leaseback transactions	$ 13,034

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical)	Dec. 31, 2018	Dec. 31, 2017
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, 2018
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. The Company’s primary customers are domestic and foreign government agencies, as well as private entities. 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 — Prior to January 1, 2018, the Company measured completion based on engineering estimates of the physical percentage completed for dredging contracts. Under the new accounting principle, revenue is recognized using contract fulfillment costs incurred to date compared to total estimated costs at completion, also known as cost-to-cost, to measure progress towards completion. Additionally, the Company capitalizes certain pre-contract and pre-construction costs, and defers recognition over the life of the contract. Fixed-price contracts, which comprise substantially all of the Company’s revenue, will most often represent a single performance obligation as the promise to transfer the individual services is not separately identifiable from other promises in the contracts and, therefore, not distinct. The Company’s performance obligations are satisfied over time and revenue is recognized using the cost-to-cost method, described above. Contract modifications are changes in the scope or price (or both) of a contract that are approved by the parties to the contract. The Company recognizes a contract modification when the parties to a contract approve a modification that either creates new, or changes existing, enforceable rights and obligations of the parties to the contract. Contract modifications are included in the transaction price only if it is probable that the modification estimate will not result in a significant reversal of revenue. 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. 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. Hourly labor generally is hired on a project-by-project basis. The Company is a party to numerous collective bargaining agreements in the U.S. that govern its relationships with its unionized hourly workforce. Effective beginning the first quarter of 2018, the Company changed the method of accounting for allocated fixed equipment costs for interim periods such that fixed equipment costs are now recognized as incurred. The Company adopted this change as a result of management’s belief that the new method is preferable and results in a more objective measure of quarterly expense that will better support planning and resource allocation decisions by management. The change has been applied retrospectively. The Company’s cost structure includes significant annual equipment-related costs, including depreciation, maintenance, insurance and long-term rentals. Previously, the Company allocated fixed equipment costs to interim periods in proportion to revenues recognized over the year. Specifically, at each interim reporting date the Company compared actual revenues earned to date on its dredging contracts to expected annual revenues and recognized equipment costs on the same proportionate basis. In the fourth quarter, any over or under allocated equipment costs were recognized such that the expense for the year equals actual equipment costs incurred during the year. 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 may represent developed technology and databases, customer relationships, and customer contracts acquired in business combinations. 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 unit 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 one operating segment which is also the Company’s one reportable segment and reporting unit of which the Company tests goodwill for impairment. The historical environmental & infrastructure segment has been retrospectively presented as discontinued operations and assets and liabilities held for sale and is no longer reflected in continuing operations. The Company performed its most recent annual test of impairment as of July 1, 2018 with no indication of impairment as of the test date. The Company will perform its next scheduled annual test of goodwill in the third quarter of 2019 should no triggering events occur which would require a test prior to the next annual test. 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 2018 or 2017. 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. In 2017, the U.S. government enacted comprehensive tax legislation referred to as the Tax Cuts and Jobs Act. Refer to Note 7, Income Taxes. 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). During 2018, the Company substantially completed the liquidation of the investment in its Brazil and Australia operations. Refer to Note 6, Fair Value Measurements, for further discussion of the closeout. Recent Accounting Pronouncements —The Company adopted Accounting Standard Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) , and subsequently issued other Accounting Standard Updates related to Accounting Standards Codification Topic 606 (collectively, “ASC 606”) on January 1, 2018 under the modified retrospective method such that the cumulative effect is recognized at the date of initial application. The adoption of ASC 606 resulted in a change in the timing of recognition of both contract revenue and costs from our prior practices. Upon the adoption of ASC 606, the Company recorded a cumulative net adjustment of $1,950 to the beginning retained earnings balance. Refer to Note 9, Revenue, for further discussion of the adoption of ASC 606. The Company adopted Accounting Standard Update No. 2016-18 (“ASU 2016-18”), Statement of Cash Flows (Topic 230): Restricted Cash In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update No. 2018-02 (“ASU 2018-02”), Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In January 2017, the FASB issued Accounting Standard Update No. 2017-04 (“ASU 2017-04”), Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment 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 February 2016, the FASB issued Accounting Standard Update No. 2016-02 (“ASU 2016-02”), Leases (Topic 842)

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2018
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. The computations for basic and diluted earnings (loss) per share for the years ended December 31, 2018, 2017 and 2016 are as follows: (shares in thousands) 2018 2017 2016 Income (loss) from continuing operations 11,016 (15,368 ) 542 Loss on discontinued operations, net of income taxes (17,309 ) (15,892 ) (8,719 ) Net loss $ (6,293 ) $ (31,260 ) $ (8,177 ) Weighted-average common shares outstanding — basic 62,236 61,365 60,744 Effect of stock options and restricted stock units 1,371 — 623 Weighted-average common shares outstanding — diluted 63,607 61,365 61,367 Earnings (loss) per share from continuing operations — basic $ 0.18 $ (0.25 ) $ 0.01 Earnings (loss) per share from continuing operations — diluted $ 0.17 $ (0.25 ) $ 0.01 For the years ended December 31, 2018, 2017 and 2016 the following amounts of stock options (“NQSO”) and restricted stock units (“RSU”) were excluded from the diluted weighted-average common shares outstanding as the Company incurred a loss during these periods: (shares in thousands) 2018 2017 2016 Effect of stock options and restricted stock units — 716 — For the years ended December 31, 2018, 2017 and 2016 the following amounts of NQSOs and RSUs 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: (shares in thousands) 2018 2017 2016 Effect of stock options and restricted stock units 1,285 2,476 1,594

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Property and Equipment	3. PROPERTY AND EQUIPMENT Property and equipment at December 31, 2018 and 2017 are as follows: 2018 2017 Land $ 9,992 $ 9,992 Buildings and improvements 5,071 5,071 Furniture and fixtures 14,087 12,453 Operating equipment 710,128 783,211 Total property and equipment 739,278 810,727 Accumulated depreciation (369,415 ) (413,802 ) Property and equipment — net $ 369,863 $ 396,925 Operating equipment of $3,537 and $8,460 was classified as held for sale, excluded from property and equipment, as of December 31, 2018 and 2017, respectively. Depreciation expense was $50,389, $55,962 and $54,826, for the years ended December 31, 2018, 2017 and 2016, respectively. For more information about changes in assets held for sale and depreciation expense related to the Company’s restructuring refer to Note 11, Restructuring Charges.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued Expenses	4. ACCRUED EXPENSES Accrued expenses at December 31, 2018 and 2017 are as follows: 2018 2017 Payroll and employee benefits $ 15,298 $ 7,658 Insurance 13,724 21,943 Fuel hedge contracts 4,710 — Interest 3,448 4,210 Contract reserves 1,709 2,720 Income and other taxes 1,175 1,764 Accrued rent 496 6,519 Other 7,791 7,112 Total accrued expenses $ 48,351 $ 51,926

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-Term Debt	5. LONG-TERM DEBT Long-term debt at December 31, 2018 and 2017 is as follows: 2018 2017 Revolving credit facility $ 11,500 $ 95,000 Notes payable — 13,296 8% senior notes 321,950 321,057 Subtotal 333,450 429,353 Current portion of revolving credit facility (11,500 ) — Current portion of notes payable — (1,212 ) Total $ 321,950 $ 428,141 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, CIBC Bank USA, 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. The Credit Agreement also provides for certain actions contemplated in the plan of restructuring with respect to the Company’s 2017 and 2018 fiscal years including allowing up to an aggregate of $20 million of expenses related to the buy-out of operating leases and allowing capital expenditures planned but not incurred by all Credit Parties in fiscal year 2017 to be carried forward to fiscal year 2018; provided that, the aggregate amount of all capital expenditures incurred by all Credit Parties in fiscal years 2017 and 2018 does not exceed $135 million. Additionally, the Credit Agreement 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, 2018, the Company had $11,500 of borrowings on the revolver and $37,749 of letters of credit outstanding, resulting in $174,555 of availability under the Credit Agreement. The availability under the Credit Agreement is suppressed by $26,196 as of December 31, 2018 as a result of certain limitations set forth in 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 and subsidiary guarantors The Company has outstanding $325,000 of 8.000% senior notes (“8% Senior Notes”) due May 15, 2022. In May 2017, the Company issued the 8% Senior Notes 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. The Company’s obligations under these Senior Notes are guaranteed by certain of the Company’s 100% owned domestic subsidiaries. Such guarantees are full, unconditional and joint and several. The parent company issuer has no independent assets or operations and all non-guarantor subsidiaries have been determined to be minor. Other The Company enters into note arrangements to finance certain vessels and ancillary equipment. In February 2018, the Company completed a sale-leaseback of a vessel yielding net proceeds of $4,500. Included in this transaction was the retirement of the asset and related equipment note, and the transaction resulted in a deferred gain. The scheduled principal payments through the maturity date of the Company’s long-term debt, excluding equipment notes and capital leases, at December 31, 2018, are as follows: Years Ending December 31, 2019 $ 11,500 2020 — 2021 — 2022 325,000 2023 — Thereafter — Total $ 336,500 The Company incurred amortization of deferred financing fees for its long term debt of $3,504, $3,280 and $2,438 for each of the years ended December 31, 2018, 2017 and 2016. Such amortization is recorded as a component of interest expense.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. 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, 2018 Quoted Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable (Level 3) Fuel hedge contracts $ 4,710 $ — $ 4,710 $ — Fair Value Measurements at Reporting Date Using Description At December 31, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fuel hedge contracts $ 2,501 $ — $ 2,501 $ — 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, 2018 and 2017 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, 2018, 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 2019. As of December 31, 2018, there were 7.8 million gallons remaining on these contracts which represent approximately 80% of the Company’s forecasted domestic fuel purchases through December 2019. Under these swap agreements, the Company will pay fixed prices ranging from $1.91 to $2.34 per gallon. At December 31, 2018, the fair value liability of the fuel hedge contracts was estimated to be $4,710 and is recorded in accrued expenses. At December 31, 2017, the fair value asset of the fuel hedge contracts was estimated to be $2,501, and is recorded in other current assets. For fuel hedge contracts considered to be highly effective, the gains reclassified to earnings from changes in fair value of derivatives, net of cash settlements and taxes, for the year ended December 31, 2018 were $1,569. The remaining gains and losses included in the accumulated other comprehensive income (loss) at December 31, 2018 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, 2018 and 2017 is as follows: Balance Sheet Location Fair Value at December 31, 2018 2017 Asset derivatives: Derivatives designated as hedging instruments Fuel hedge contracts Other current assets $ — $ 2,501 Liability derivatives: Derivatives designated as hedging instruments Fuel hedge contracts Accrued expenses $ 4,710 $ — 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. Accumulated other comprehensive income (loss) Changes in the components of the accumulated balances of other comprehensive income (loss) are as follows: 2018 2017 2016 Cumulative translation adjustments—net of tax $ 1,513 $ (41 ) $ 508 Derivatives: Reclassification of derivative (gains) losses to earnings—net of tax (1,569 ) (218 ) 30 Change in fair value of derivatives—net of tax (3,756 ) 1,407 300 Net unrealized (gain) loss on derivatives—net of tax (5,325 ) 1,189 330 Total other comprehensive income (loss) $ (3,812 ) $ 1,148 $ 838 Adjustments reclassified from accumulated balances of other comprehensive income (loss) to earnings are as follows: Statement of Operations Location 2018 2017 2016 Derivatives: Fuel hedge contracts Costs of contract revenues $ (2,125 ) $ (358 ) $ 50 Income tax (provision) benefit (556 ) 140 20 $ (1,569 ) $ (218 ) $ 30 The Company substantially completed the liquidation of the investment in its Brazil and Australia operations during 2018. This liquidation resulted in the reversal of the Company’s cumulative translation adjustment. Adjustments reclassified from accumulated balances of other comprehensive income (loss) to earnings are as follows: Statement of Operations Location 2018 2017 2016 Cumulative translation adjustment: Other expense $ (2,337 ) $ — $ — Income tax benefit 612 — — $ (1,725 ) $ — $ — 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, 2018 (See Note 5, Long-Term Debt). The 8% 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 $330,281 at December 31, 2018, 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, 2018
Income Tax Disclosure [Abstract]
Income Taxes	7. The Company’s income tax benefit from continuing and discontinued operations for the year ended December 31, 2018 is as follows: 2018 2017 2016 Income tax provision (benefit) from continuing operations $ 5,437 $ (33,761 ) $ (177 ) Income tax benefit from discontinued operations (6,162 ) (10,052 ) (5,615 ) Income tax benefit $ (725 ) $ (43,813 ) $ (5,792 ) The Company’s income (loss) from continuing operations before income tax from domestic and foreign continuing operations for the years ended December 31, 2018, 2017 and 2016 is as follows: 2018 2017 2016 Domestic operations $ 26,878 $ (12,263 ) $ 12,039 Foreign operations (10,425 ) (36,866 ) (11,674 ) Total income (loss) from continuing operations before income tax $ 16,453 $ (49,129 ) $ 365 The provision (benefit) for income taxes from continuing operations as of December 31, 2018, 2017 and 2016 is as follows: 2018 2017 2016 Federal: Current $ — $ (248 ) $ 260 Deferred 3,702 (31,957 ) (129 ) State: Current 48 29 54 Deferred 1,687 (1,598 ) (508 ) Foreign: Current — 13 146 Deferred — — — Total $ 5,437 $ (33,761 ) $ (177 ) The Company’s income tax benefit from continuing operations reconciles to the provision at the statutory U.S. federal income tax rate of 21% for the year ended December 31, 2018 and 35% for the years ended December 31, 2017 and 2016 as follows: 2018 2017 2016 Tax provision (benefit) at statutory U.S. federal income tax rate $ 3,455 $ (17,194 ) $ 128 State income tax — net of federal income tax benefit 937 (1,746 ) (227 ) Impact of Tax Cuts and Job Act — (15,720 ) — Change in state law regarding NOL carryforwards 658 — — Nondeductible officer compensation 201 — — Change in deferred state tax rate — — (1,043 ) Research and development tax credits (218 ) (170 ) (253 ) Changes in unrecognized tax benefits 14 10 10 Changes in valuation allowance 116 1,152 821 Other 274 (93 ) 387 Income tax provision (benefit) $ 5,437 $ (33,761 ) $ (177 ) 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, from continuing operations. As the Company was in a net deferred tax liability position as of the date of enactment of the Tax Act, the impact to the Company was 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, 2018 and 2017, the Company had loss carryforwards for federal income tax purposes of $168,650 and $207,875 respectively, which expire between 2034 and 2037. At December 31, 2018 and 2017, the Company had gross net operating loss carryforwards for state income tax purposes totaling $190,901 and $209,877, respectively, which expire between 2023 and 2028. 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 and by $116 in 2018. The Company also has foreign gross net operating loss carryforwards of approximately $9,533 and $7,637 as of December 31, 2018 and 2017, of which $2,876 expires between 2018 and 2028. The remaining amount of $6,657 may be carried forward indefinitely. At December 31, 2018 and 2017, a full valuation allowance has been established for the deferred tax asset of $2,338 and $1,962 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, 2018 and 2017, 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. 2018 2017 2016 Unrecognized tax benefits — January 1 $ 157 $ 157 $ 157 Gross increases — tax positions in prior period — — — Gross increases — current period tax positions — — — Gross decreases — expirations — — — Gross decreases — tax positions in prior period — — — 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, 2018 and 2017, the Company had approximately $71 and $53, 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 2015 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 2014. In foreign jurisdictions in which the Company operates, years prior to 2013 are closed and are no longer subject to examination. The Company’s deferred tax assets (liabilities) at December 31, 2018 and 2017 are as follows: 2018 2017 Deferred tax assets: Accrued liabilities $ 9,287 $ 8,119 Federal NOLs 35,417 43,654 Foreign NOLs 2,338 1,962 State NOLs 10,796 12,382 Tax credit carryforwards 2,159 1,941 Charitable contribution 910 1,340 Valuation allowance (4,786 ) (4,294 ) Total deferred tax assets 56,121 65,104 Deferred tax liabilities: Depreciation and amortization (78,967 ) (89,966 ) Other liabilities — (699 ) Total deferred tax liabilities (78,967 ) (90,665 ) Net noncurrent deferred tax liabilities $ (22,846 ) $ (25,561 ) 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, 2018 and 2017 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, 2018 and 2017 would ultimately be realized and determined that no valuation allowance was required.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	8. 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 $4,643, $2,917 and $2,651, for the years ended December 31, 2018, 2017 and 2016, 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 2018, 2017 and 2016. A summary of stock option activity under the Incentive Plan as of December 31, 2018, and changes during the year ended December 31, 2018, is presented below: Options Shares Weighted Exercise Price Weighted-Average Remaining Contract Term (yrs) Aggregate Intrinsic Value ($000's) Outstanding as of January 1, 2018 1,377 $ 6.34 Granted — — Exercised (62 ) 4.78 Forfeited or Expired (155 ) 5.60 Outstanding as of December 31, 2018 1,160 $ 6.52 2.8 $ 646 Vested at December 31, 2018 1,160 $ 6.52 2.8 $ 646 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, 2018, and changes during the year ended December 31, 2018, is presented below: Nonvested Restricted Stock Units Shares Weighted-Average Grant-Date Fair Value Outstanding as of January 1, 2018 2,196 $ 5.06 Granted 2,051 4.83 Vested (758 ) 4.95 Forfeited (501 ) 5.44 Outstanding as of December 31, 2018 2,988 $ 4.88 Expected to vest at December 31, 2018 2,084 $ 4.63 As of December 31, 2018, there was $4,827 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 $1,205 and $328 for the years ended December 31, 2018 and 2017, 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 or deferred restricted stock units of the Company. Directors may elect to receive some or all of the cash retainer in common stock or deferred restricted stock units. In 2018, the Chairman of the Board received an additional $100 of annual compensation, paid 100% in common stock. In the years ended December 31, 2018, 2017 and 2016, 156 thousand, 207 thousand and 86 thousand shares, respectively, of the Company’s common stock or restricted stock units were issued to non-employee directors under the Incentive Plan.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Revenue	9. REVENUE The Company’s revenue is derived from contracts for services with federal, state, local and foreign governmental entities and private customers. Revenues are generally derived from the enhancement or preservation of navigability of waterways or the protection of shorelines through the removal or replenishment of soil, sand or rock. Prior to January 1, 2018, the Company measured completion based on engineering estimates of the physical percentage completed for dredging contracts. Under the new accounting principle, the Company measures progress toward completion on all contracts utilizing the cost-to-cost method. Additionally, the Company capitalizes certain pre-contract and pre-construction costs, and defers recognition over the life of the contract. At December 31, 2018, the impact of this change in accounting principle on the Consolidated Balance Sheets is as follows: December 31, 2018 ASSETS Contract revenues in excess of billings $ (18,334 ) Other current assets 8,953 Other 4,176 LIABILITIES AND EQUITY Accrued expenses (5,306 ) Billings in excess of contract revenues 5,834 Deferred taxes (1,468 ) Accumulated deficit $ (4,265 ) For the year ended December 31, 2018, the impact of this change in accounting principle on the Consolidated Statements of Operations is as follows: 2018 Contract revenues $ (14,696 ) Cost of contract revenues (11,360 ) Income tax benefit 867 Loss from continuing operations (2,469 ) Net loss $ (2,469 ) Comprehensive loss $ (2,469 ) Performance obligations A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account upon which the Company’s revenue is calculated. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue as the performance obligation is satisfied. Fixed-price contracts, which comprise substantially all of the Company’s revenue, will most often represent a single performance obligation as the promise to transfer the individual services is not separately identifiable from other promises in the contracts and, therefore, not distinct. The Company capitalizes certain pre-contract and pre-construction costs, and defers recognition over the life of the contract. The Company’s performance obligations are satisfied over time and revenue is recognized using contract fulfillment costs incurred to date compared to total estimated costs at completion, also known as cost-to-cost, to measure progress towards completion. As the Company’s performance creates an asset that customer controls, this method provides a faithful depiction of the transfer of an asset to the customer. Generally, the Company has an enforceable right to payment for performance completed to date. The Company typically satisfies its performance obligations upon completion of service. The majority of the Company’s contracts are completed in a year or less. At December 31, 2018, the Company had $707,091 of remaining performance obligations, which the Company refers to as total backlog. Approximately 76% of the Company’s backlog will be completed in 2019 with the remaining balance expected to be completed by 2020. Transaction price The transaction price is calculated using the Company’s estimated costs to complete a project. These costs are based on the types of equipment required to perform the specified service, project site conditions, the estimated project duration, seasonality, location and complexity of a project. The nature of the Company’s contracts gives rise to several types of variable consideration, including pay on quantity dredged for dredging projects and contract modifications for both dredging and environmental & infrastructure projects. Estimated pay quantity is the amount of material the Company expects to dredge for which it will receive payment. Estimated quantity to be dredged is calculated using engineering estimates based on current survey data and the Company’s knowledge based on historical project experience. Contract modifications are changes in the scope or price (or both) of a contract that are approved by the parties to the contract. The Company recognizes a contract modification when the parties to a contract approve a modification that either creates new, or changes existing, enforceable rights and obligations of the parties to the contract. Contract modifications are included in the transaction price only if it is probable that the modification estimate will not result in a significant reversal of revenue. Contract modifications are routine in the performance of the Company’s contracts. In most instances, contract modifications are for services that are not distinct, and, therefore, are accounted for as part of the existing contract. 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. Revenue by category Domestically, our work generally is performed in coastal waterways and deep water ports. The U.S. dredging market consists of four primary types of work: capital, coastal protection, maintenance and rivers & lakes. The following table sets forth, by type of work, the Company’s contract revenues for the years ended December 31, 2018, 2017 and 2016: Revenues 2018 2017 2016 Capital—U.S. $ 333,037 $ 185,113 $ 219,914 Capital—foreign 14,088 42,306 59,413 Coastal protection 175,923 191,070 215,041 Maintenance 53,427 134,923 92,274 Rivers & lakes 44,320 38,747 50,826 Total revenues $ 620,795 $ 592,159 $ 637,468 The following table sets forth, by type of customer, the Company’s contract revenues for the years ended December 31, 2018, 2017 and 2016: Revenues 2018 2017 2016 Federal government $ 468,421 $ 375,276 $ 409,941 State and local government 93,499 145,196 126,395 Private 44,787 29,381 41,719 Foreign 14,088 42,306 59,413 Total revenues $ 620,795 $ 592,159 $ 637,468 Foreign dredging revenue was $14,088, $42,306 and $59,413 for the years ended December 31, 2018, 2017 and 2016 respectively, and was mostly attributable to work done in the Middle East. Contract balances Billings on contracts are generally submitted after verification with the customers of physical progress and are recognized as accounts receivable in the balance sheet. For billings that do 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. Certain pre-contract and pre-construction costs are capitalized and reflected as contract assets in the balance sheet. Customer advances, deposits and commissions are reflected in the balance sheet as contract liabilities. Accounts receivable at December 31, 2018 and December 31, 2017 are as follows: 2018 2017 Completed contracts $ 8,592 $ 10,658 Contracts in progress 48,418 28,212 Retainage 7,969 17,545 64,979 56,415 Allowance for doubtful accounts (200 ) — Total accounts receivable—net $ 64,779 $ 56,415 Current portion of accounts receivable—net $ 64,779 $ 51,940 Long-term accounts receivable and retainage — 4,475 Total accounts receivable—net $ 64,779 $ 56,415 The components of contracts in progress at December 31, 2018 and December 31, 2017 are as follows: 2018 2017 Costs and earnings in excess of billings: Costs and earnings for contracts in progress $ 433,093 $ 507,037 Amounts billed (416,956 ) (451,829 ) Costs and earnings in excess of billings for contracts in progress 16,137 55,208 Costs and earnings in excess of billings for completed contracts 3,928 22,699 Total contract revenues in excess of billings $ 20,065 $ 77,907 Current portion of contract revenues in excess of billings $ 17,953 $ 77,907 Long-term contract revenues in excess of billings 2,112 — Total contract revenues in excess of billings $ 20,065 $ 77,907 Billings in excess of costs and earnings: Amounts billed $ (260,691 ) $ (301,788 ) Costs and earnings for contracts in progress 242,898 299,202 Total billings in excess of contract revenues $ (17,793 ) $ (2,586 ) For amounts included in billings in excess of contract revenues balance at the beginning of the year, the Company recognized nearly all of the related revenue during the year ended December 31, 2018. At December 31, 2018 and January 1, 2018, costs to fulfill contracts with customers recognized as an asset were $13,129 and $6,754, respectively, and are recorded in other current assets and other noncurrent assets. These costs relate to pre-contract and pre-construction activities. During the year ended December 31, 2018, the company amortized $15,411 of pre-construction costs, respectively. The Company derived revenues and gross profit from foreign project operations for the years ended December 31, 2018, 2017, and 2016, as follows: 2018 2017 2016 Contract revenues $ 14,088 $ 42,306 $ 59,413 Costs of contract revenues (19,866 ) (73,958 ) (66,729 ) Gross profit $ (5,778 ) $ (31,652 ) $ (7,316 ) In 2018, 2017 and 2016, 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, 2018 and 2017, long-lived assets with a net book value of $30,601 and $47,563, 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 2018, 2017 and 2016, 75.5%, 63.4% and 64.3%, 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, 2018 and 2017, approximately 65.3% and 42.8%, 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. Revenue from foreign projects has been concentrated in the Middle East which comprised less than 10% in 2018, 2017 and 2016. At December 31, 2018 and 2017, less than 10% 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.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Retirement Plans	10. RETIREMENT PLANS The Company sponsors two 401(k) savings plans, one covering substantially all non-union salaried employees (“Salaried Plan”), a second covering its hourly employees (“Hourly Plan”). Under the Salaried Plan and the Hourly Plan, individual employees may contribute a percentage of compensation and the Company will match a portion of the employees’ contributions. The Salaried Plan also includes 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 2018, 2017 and 2016, was $5,060, $2,616 and $2,686, respectively. The Company also contributes to various multiemployer pension plans pursuant to collective bargaining agreements. In 2018, 2017 and 2016, the Company contributed $4,207, $4,699 and $4,793 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. 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, 2018
Restructuring And Related Activities [Abstract]
Restructuring Charges	11. 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. Management executed 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. The cumulative amounts incurred to date for restructuring charges, including amounts presented in discontinued operations, include severance of $3,549, asset retirements of $32,309, pre-contract costs of $6,441 and closeout costs of $4,194. Restructuring activities were substantially completed in 2018. Restructuring charges recognized for the above actions for the years ended December 31, 2018 and 2017 are summarized as follows: 2018 2017 Costs of contract revenues—depreciation $ 6,759 $ 6,859 Costs of contract revenues—other 2,292 16,102 General and administrative expenses 185 1,189 Loss on sale of assets—net 4,572 4,691 Other expense 2,337 — Total 16,145 28,841 The Company accrued severance expense of $662 and $1,403 at December 31, 2018 and December 31, 2017, respectively, which are expected to be settled in 2019. Accrued severance is included in accrued expenses.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. 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 14, 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 the 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 is in the process of negotiating a Consent Order with the Florida Department of Environmental Protection regarding alleged impacts to a seagrass habitat in connection with a project in Charlotte County, Florida. The Company estimates the range of potential loss related to this matter as between $200,000 and $250,000. In September 2018, the EPA Region 4 informed the Company of the EPA’s intent to file an administrative complaint against the Company relating to a project the Company performed at PortMiami from 2013-2015, although no complaint has been filed to date, to the Company’s knowledge. The EPA is alleging violations of Section 103 of the Marine Protection, Research, and Sanctuaries Act (“MPRSA”) and failure to report violations of the MPRSA. The Company disagrees with the EPA on whether a violation occurred and, if a violation did occur, the appropriate penalty calculation, and we will defend ourselves vigorously. Except as noted above, 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 2025. 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, 2018, are as follows: 2019 $ 26,554 2020 22,349 2021 18,430 2022 13,552 2023 9,041 Thereafter 8,697 Total minimum operating lease payments $ 98,623 Total rent expense under long-term operating lease arrangements for the years ended December 31, 2018, 2017 and 2016 was $21,160, $26,664 and $20,006, 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 2018 related to the Company’s restructuring refer to Note 11, Restructuring Charges.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	13. RELATED-PARTY TRANSACTIONS The Company’s historical 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 on rent on these properties in 2016. Further, the Company’s historical 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. In March 2017, one of the properties was sold to a non-related party. In 2018, 2017 and 2016, the Company paid rent of $222, $263 and $506, respectively, for these two properties.

Business Dispositions

Business Dispositions	12 Months Ended
	Dec. 31, 2018
Discontinued Operations And Disposal Groups [Abstract]
Business Dispositions	14. BUSINESS DISPOSITIONS Discontinued operations Businesses or asset groups are reported as discontinued operations when the Company commits to a plan to divest the business or group and the sale of the business or asset group is deemed probable within the next twelve months. Further, the disposal must represent a strategic shift that has (or will have) a major effect on the Company’s operations and financial results. In the fourth quarter, the management team proposed, and the Board of Directors approved, a plan to sell the Company’s historical environmental & infrastructure business. The Company has retained a financial advisor to assist with the process and expects to finalize disposition of the environmental & infrastructure business in the first half of 2019. The disposal group of the historical environmental & infrastructure business has therefore been classified as discontinued operations and assets and liabilities held for sale for all periods presented. Included in the results of discontinued operations for the year ended December 31, 2018 is a provision of $14,110 to reduce the net assets of the historical environmental & infrastructure business to fair value less costs to sell. Fair values were determined using expected sales terms and an evaluation of working capital. The loss on disposition of assets held for sale is subject to change prior to completion of the disposition and could differ materially from the Company’s estimate. To the extent the Company incurs liabilities for exit costs, including severance, other employee benefit costs and operating lease obligations, the liabilities will be measured at fair value and recorded when incurred. The results of the business have been reported in discontinued operations as follows: 2018 2017 2016 Revenue $ 76,843 $ 112,607 $ 133,637 Loss before income taxes from discontinued operations $ (9,361 ) $ (25,944 ) $ (14,334 ) Preliminary loss on disposal of assets held for sale (14,110 ) — — Income tax benefit 6,162 10,052 5,615 Loss from discontinued operations, net of income taxes $ (17,309 ) $ (15,892 ) $ (8,719 ) The major classes of assets and liabilities of businesses reported as discontinued operations are shown below: 2018 2017 Assets: Accounts receivable—net $ 13,943 $ 23,593 Contract revenues in excess of billings 9,971 12,881 Other current assets 865 1,943 Assets held for sale $ 24,779 $ 38,417 Property and equipment—net 6,612 10,369 Goodwill 7,000 7,000 Other intangible assets—net 372 907 Other assets 1,699 2,825 Reserve for loss on disposal (14,110 ) — Assets held for sale—noncurrent $ 1,573 $ 21,101 Liabilities: Accounts payable $ 8,343 $ 22,505 Accrued expenses 4,380 4,292 Other current liabilities 1,217 2,576 Liabilities held for sale 13,940 29,373 Other liabilities 146 773 Liabilities held for sale—noncurrent $ 146 $ 773 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 12, 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 12, Commitments and Contingencies, 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.

Schedule II-Valuation and Quali

Schedule II-Valuation and Qualify Accounts	12 Months Ended
	Dec. 31, 2018
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, 2018, 2017 and 2016 (In thousands) Beginning Balance Additions Deductions Ending balance Description Year ended December 31, 2016 Allowances deducted from assets to which they apply: Allowances for doubtful accounts $ 578 $ — $ (320 ) $ 258 Valuation allowance for deferred tax assets 6,101 1,032 — 7,133 Total $ 6,679 $ 1,032 $ (320 ) $ 7,391 Year ended December 31, 2017 Allowances deducted from assets to which they apply: Allowances for doubtful accounts $ 258 $ — $ (258 ) $ — Valuation allowance for deferred tax assets 7,133 1,152 (3,991 ) 4,294 Total $ 7,391 $ 1,152 $ (4,249 ) $ 4,294 Year ended December 31, 2018 Allowances deducted from assets to which they apply: Allowances for doubtful accounts $ — $ 200 $ — $ 200 Valuation allowance for deferred tax assets 4,294 492 — 4,786 Total $ 4,294 $ 692 $ — $ 4,986

Nature of Business and Summar_2

Nature of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
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 — Prior to January 1, 2018, the Company measured completion based on engineering estimates of the physical percentage completed for dredging contracts. Under the new accounting principle, revenue is recognized using contract fulfillment costs incurred to date compared to total estimated costs at completion, also known as cost-to-cost, to measure progress towards completion. Additionally, the Company capitalizes certain pre-contract and pre-construction costs, and defers recognition over the life of the contract. Fixed-price contracts, which comprise substantially all of the Company’s revenue, will most often represent a single performance obligation as the promise to transfer the individual services is not separately identifiable from other promises in the contracts and, therefore, not distinct. The Company’s performance obligations are satisfied over time and revenue is recognized using the cost-to-cost method, described above. Contract modifications are changes in the scope or price (or both) of a contract that are approved by the parties to the contract. The Company recognizes a contract modification when the parties to a contract approve a modification that either creates new, or changes existing, enforceable rights and obligations of the parties to the contract. Contract modifications are included in the transaction price only if it is probable that the modification estimate will not result in a significant reversal of revenue. 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. 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. Hourly labor generally is hired on a project-by-project basis. The Company is a party to numerous collective bargaining agreements in the U.S. that govern its relationships with its unionized hourly workforce. Effective beginning the first quarter of 2018, the Company changed the method of accounting for allocated fixed equipment costs for interim periods such that fixed equipment costs are now recognized as incurred. The Company adopted this change as a result of management’s belief that the new method is preferable and results in a more objective measure of quarterly expense that will better support planning and resource allocation decisions by management. The change has been applied retrospectively. The Company’s cost structure includes significant annual equipment-related costs, including depreciation, maintenance, insurance and long-term rentals. Previously, the Company allocated fixed equipment costs to interim periods in proportion to revenues recognized over the year. Specifically, at each interim reporting date the Company compared actual revenues earned to date on its dredging contracts to expected annual revenues and recognized equipment costs on the same proportionate basis. In the fourth quarter, any over or under allocated equipment costs were recognized such that the expense for the year equals actual equipment costs incurred during the year.
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 may represent developed technology and databases, customer relationships, and customer contracts acquired in business combinations. 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 unit 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 one operating segment which is also the Company’s one reportable segment and reporting unit of which the Company tests goodwill for impairment. The historical environmental & infrastructure segment has been retrospectively presented as discontinued operations and assets and liabilities held for sale and is no longer reflected in continuing operations. The Company performed its most recent annual test of impairment as of July 1, 2018 with no indication of impairment as of the test date. The Company will perform its next scheduled annual test of goodwill in the third quarter of 2019 should no triggering events occur which would require a test prior to the next annual test.
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 2018 or 2017. 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. In 2017, the U.S. government enacted comprehensive tax legislation referred to as the Tax Cuts and Jobs Act. Refer to Note 7, Income Taxes.
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). During 2018, the Company substantially completed the liquidation of the investment in its Brazil and Australia operations. Refer to Note 6, Fair Value Measurements, for further discussion of the closeout.
Recent Accounting Pronouncements	Recent Accounting Pronouncements —The Company adopted Accounting Standard Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) , and subsequently issued other Accounting Standard Updates related to Accounting Standards Codification Topic 606 (collectively, “ASC 606”) on January 1, 2018 under the modified retrospective method such that the cumulative effect is recognized at the date of initial application. The adoption of ASC 606 resulted in a change in the timing of recognition of both contract revenue and costs from our prior practices. Upon the adoption of ASC 606, the Company recorded a cumulative net adjustment of $1,950 to the beginning retained earnings balance. Refer to Note 9, Revenue, for further discussion of the adoption of ASC 606. The Company adopted Accounting Standard Update No. 2016-18 (“ASU 2016-18”), Statement of Cash Flows (Topic 230): Restricted Cash In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update No. 2018-02 (“ASU 2018-02”), Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In January 2017, the FASB issued Accounting Standard Update No. 2017-04 (“ASU 2017-04”), Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment 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 February 2016, the FASB issued Accounting Standard Update No. 2016-02 (“ASU 2016-02”), Leases (Topic 842)

Nature of Business and Summar_3

Nature of Business and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018
Earnings Per Share [Abstract]
Computations for Basic and Diluted Loss Per Share	The computations for basic and diluted earnings (loss) per share for the years ended December 31, 2018, 2017 and 2016 are as follows: (shares in thousands) 2018 2017 2016 Income (loss) from continuing operations 11,016 (15,368 ) 542 Loss on discontinued operations, net of income taxes (17,309 ) (15,892 ) (8,719 ) Net loss $ (6,293 ) $ (31,260 ) $ (8,177 ) Weighted-average common shares outstanding — basic 62,236 61,365 60,744 Effect of stock options and restricted stock units 1,371 — 623 Weighted-average common shares outstanding — diluted 63,607 61,365 61,367 Earnings (loss) per share from continuing operations — basic $ 0.18 $ (0.25 ) $ 0.01 Earnings (loss) per share from continuing operations — diluted $ 0.17 $ (0.25 ) $ 0.01
Schedule of Stock Options and Restricted Stock Units Excluded from Diluted Weighted-Average Common Shares	For the years ended December 31, 2018, 2017 and 2016 the following amounts of stock options (“NQSO”) and restricted stock units (“RSU”) were excluded from the diluted weighted-average common shares outstanding as the Company incurred a loss during these periods: (shares in thousands) 2018 2017 2016 Effect of stock options and restricted stock units — 716 —
Schedule of Stock Options and Restricted Stock Units Excluded from Calculation of Anti-Diluted Earnings Per Share	For the years ended December 31, 2018, 2017 and 2016 the following amounts of NQSOs and RSUs 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: (shares in thousands) 2018 2017 2016 Effect of stock options and restricted stock units 1,285 2,476 1,594

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Schedule of Property Plant and Equipment	Property and equipment at December 31, 2018 and 2017 are as follows: 2018 2017 Land $ 9,992 $ 9,992 Buildings and improvements 5,071 5,071 Furniture and fixtures 14,087 12,453 Operating equipment 710,128 783,211 Total property and equipment 739,278 810,727 Accumulated depreciation (369,415 ) (413,802 ) Property and equipment — net $ 369,863 $ 396,925

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued Expenses	Accrued expenses at December 31, 2018 and 2017 are as follows: 2018 2017 Payroll and employee benefits $ 15,298 $ 7,658 Insurance 13,724 21,943 Fuel hedge contracts 4,710 — Interest 3,448 4,210 Contract reserves 1,709 2,720 Income and other taxes 1,175 1,764 Accrued rent 496 6,519 Other 7,791 7,112 Total accrued expenses $ 48,351 $ 51,926

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	Long-term debt at December 31, 2018 and 2017 is as follows: 2018 2017 Revolving credit facility $ 11,500 $ 95,000 Notes payable — 13,296 8% senior notes 321,950 321,057 Subtotal 333,450 429,353 Current portion of revolving credit facility (11,500 ) — Current portion of notes payable — (1,212 ) Total $ 321,950 $ 428,141
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, 2018, are as follows: Years Ending December 31, 2019 $ 11,500 2020 — 2021 — 2022 325,000 2023 — Thereafter — Total $ 336,500

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 Quoted Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable (Level 3) Fuel hedge contracts $ 4,710 $ — $ 4,710 $ — Fair Value Measurements at Reporting Date Using Description At December 31, 2017 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fuel hedge contracts $ 2,501 $ — $ 2,501 $ —
Schedule of Fair Value of Fuel Hedge Contracts Balance Sheet Location	The fair value of the fuel hedge contracts outstanding as of December 31, 2018 and 2017 is as follows: Balance Sheet Location Fair Value at December 31, 2018 2017 Asset derivatives: Derivatives designated as hedging instruments Fuel hedge contracts Other current assets $ — $ 2,501 Liability derivatives: Derivatives designated as hedging instruments Fuel hedge contracts Accrued expenses $ 4,710 $ —
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: 2018 2017 2016 Cumulative translation adjustments—net of tax $ 1,513 $ (41 ) $ 508 Derivatives: Reclassification of derivative (gains) losses to earnings—net of tax (1,569 ) (218 ) 30 Change in fair value of derivatives—net of tax (3,756 ) 1,407 300 Net unrealized (gain) loss on derivatives—net of tax (5,325 ) 1,189 330 Total other comprehensive income (loss) $ (3,812 ) $ 1,148 $ 838
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 2018 2017 2016 Derivatives: Fuel hedge contracts Costs of contract revenues $ (2,125 ) $ (358 ) $ 50 Income tax (provision) benefit (556 ) 140 20 $ (1,569 ) $ (218 ) $ 30 Adjustments reclassified from accumulated balances of other comprehensive income (loss) to earnings are as follows: Statement of Operations Location 2018 2017 2016 Cumulative translation adjustment: Other expense $ (2,337 ) $ — $ — Income tax benefit 612 — — $ (1,725 ) $ — $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Income tax Benefit from Continuing and Discontinuing Operations	2018 2017 2016 Income tax provision (benefit) from continuing operations $ 5,437 $ (33,761 ) $ (177 ) Income tax benefit from discontinued operations (6,162 ) (10,052 ) (5,615 ) Income tax benefit $ (725 ) $ (43,813 ) $ (5,792 )
Income (Loss) from Continuing Operations before Income Tax from Domestic and Foreign Operations	2018 2017 2016 Domestic operations $ 26,878 $ (12,263 ) $ 12,039 Foreign operations (10,425 ) (36,866 ) (11,674 ) Total income (loss) from continuing operations before income tax $ 16,453 $ (49,129 ) $ 365
Provision (Benefit) For Income Taxes	2018 2017 2016 Federal: Current $ — $ (248 ) $ 260 Deferred 3,702 (31,957 ) (129 ) State: Current 48 29 54 Deferred 1,687 (1,598 ) (508 ) Foreign: Current — 13 146 Deferred — — — Total $ 5,437 $ (33,761 ) $ (177 )
Income Tax Benefit Reconciliation	2018 2017 2016 Tax provision (benefit) at statutory U.S. federal income tax rate $ 3,455 $ (17,194 ) $ 128 State income tax — net of federal income tax benefit 937 (1,746 ) (227 ) Impact of Tax Cuts and Job Act — (15,720 ) — Change in state law regarding NOL carryforwards 658 — — Nondeductible officer compensation 201 — — Change in deferred state tax rate — — (1,043 ) Research and development tax credits (218 ) (170 ) (253 ) Changes in unrecognized tax benefits 14 10 10 Changes in valuation allowance 116 1,152 821 Other 274 (93 ) 387 Income tax provision (benefit) $ 5,437 $ (33,761 ) $ (177 )
Reconciliation of Unrecognized Tax Benefits	2018 2017 2016 Unrecognized tax benefits — January 1 $ 157 $ 157 $ 157 Gross increases — tax positions in prior period — — — Gross increases — current period tax positions — — — Gross decreases — expirations — — — Gross decreases — tax positions in prior period — — — Unrecognized tax benefits — December 31, $ 157 $ 157 $ 157
Deferred Tax Assets (Liabilities)	2018 2017 Deferred tax assets: Accrued liabilities $ 9,287 $ 8,119 Federal NOLs 35,417 43,654 Foreign NOLs 2,338 1,962 State NOLs 10,796 12,382 Tax credit carryforwards 2,159 1,941 Charitable contribution 910 1,340 Valuation allowance (4,786 ) (4,294 ) Total deferred tax assets 56,121 65,104 Deferred tax liabilities: Depreciation and amortization (78,967 ) (89,966 ) Other liabilities — (699 ) Total deferred tax liabilities (78,967 ) (90,665 ) Net noncurrent deferred tax liabilities $ (22,846 ) $ (25,561 )

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018, and changes during the year ended December 31, 2018, is presented below: Options Shares Weighted Exercise Price Weighted-Average Remaining Contract Term (yrs) Aggregate Intrinsic Value ($000's) Outstanding as of January 1, 2018 1,377 $ 6.34 Granted — — Exercised (62 ) 4.78 Forfeited or Expired (155 ) 5.60 Outstanding as of December 31, 2018 1,160 $ 6.52 2.8 $ 646 Vested at December 31, 2018 1,160 $ 6.52 2.8 $ 646
Summary of Non-Vested Restricted Stock Units	A summary of the status of the Company’s non-vested RSUs as of December 31, 2018, and changes during the year ended December 31, 2018, is presented below: Nonvested Restricted Stock Units Shares Weighted-Average Grant-Date Fair Value Outstanding as of January 1, 2018 2,196 $ 5.06 Granted 2,051 4.83 Vested (758 ) 4.95 Forfeited (501 ) 5.44 Outstanding as of December 31, 2018 2,988 $ 4.88 Expected to vest at December 31, 2018 2,084 $ 4.63

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Line Items]
Summary of Type of Work and Customer, Contract Revenues	The following table sets forth, by type of work, the Company’s contract revenues for the years ended December 31, 2018, 2017 and 2016: Revenues 2018 2017 2016 Capital—U.S. $ 333,037 $ 185,113 $ 219,914 Capital—foreign 14,088 42,306 59,413 Coastal protection 175,923 191,070 215,041 Maintenance 53,427 134,923 92,274 Rivers & lakes 44,320 38,747 50,826 Total revenues $ 620,795 $ 592,159 $ 637,468 The following table sets forth, by type of customer, the Company’s contract revenues for the years ended December 31, 2018, 2017 and 2016: Revenues 2018 2017 2016 Federal government $ 468,421 $ 375,276 $ 409,941 State and local government 93,499 145,196 126,395 Private 44,787 29,381 41,719 Foreign 14,088 42,306 59,413 Total revenues $ 620,795 $ 592,159 $ 637,468
Schedule of Accounts Receivable	Accounts receivable at December 31, 2018 and December 31, 2017 are as follows: 2018 2017 Completed contracts $ 8,592 $ 10,658 Contracts in progress 48,418 28,212 Retainage 7,969 17,545 64,979 56,415 Allowance for doubtful accounts (200 ) — Total accounts receivable—net $ 64,779 $ 56,415 Current portion of accounts receivable—net $ 64,779 $ 51,940 Long-term accounts receivable and retainage — 4,475 Total accounts receivable—net $ 64,779 $ 56,415
Components of Contracts in Progress	The components of contracts in progress at December 31, 2018 and December 31, 2017 are as follows: 2018 2017 Costs and earnings in excess of billings: Costs and earnings for contracts in progress $ 433,093 $ 507,037 Amounts billed (416,956 ) (451,829 ) Costs and earnings in excess of billings for contracts in progress 16,137 55,208 Costs and earnings in excess of billings for completed contracts 3,928 22,699 Total contract revenues in excess of billings $ 20,065 $ 77,907 Current portion of contract revenues in excess of billings $ 17,953 $ 77,907 Long-term contract revenues in excess of billings 2,112 — Total contract revenues in excess of billings $ 20,065 $ 77,907 Billings in excess of costs and earnings: Amounts billed $ (260,691 ) $ (301,788 ) Costs and earnings for contracts in progress 242,898 299,202 Total billings in excess of contract revenues $ (17,793 ) $ (2,586 )
Summary of Revenues and Gross Profit from Foreign Project Operations	The Company derived revenues and gross profit from foreign project operations for the years ended December 31, 2018, 2017, and 2016, as follows: 2018 2017 2016 Contract revenues $ 14,088 $ 42,306 $ 59,413 Costs of contract revenues (19,866 ) (73,958 ) (66,729 ) Gross profit $ (5,778 ) $ (31,652 ) $ (7,316 )
ASU 2014-09 [Member]
Revenue From Contract With Customer [Line Items]
Summary of Impact of Change in Accounting Principle on Consolidated Balance Sheets	At December 31, 2018, the impact of this change in accounting principle on the Consolidated Balance Sheets is as follows: December 31, 2018 ASSETS Contract revenues in excess of billings $ (18,334 ) Other current assets 8,953 Other 4,176 LIABILITIES AND EQUITY Accrued expenses (5,306 ) Billings in excess of contract revenues 5,834 Deferred taxes (1,468 ) Accumulated deficit $ (4,265 )
Summary of Impact of Change in Accounting Principle on Consolidated Statements of Operations	For the year ended December 31, 2018, the impact of this change in accounting principle on the Consolidated Statements of Operations is as follows: 2018 Contract revenues $ (14,696 ) Cost of contract revenues (11,360 ) Income tax benefit 867 Loss from continuing operations (2,469 ) Net loss $ (2,469 ) Comprehensive loss $ (2,469 )

Restructuring charges (Tables)

Restructuring charges (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring And Related Activities [Abstract]
Schedule of Restructuring Charges	Restructuring charges recognized for the above actions for the years ended December 31, 2018 and 2017 are summarized as follows: 2018 2017 Costs of contract revenues—depreciation $ 6,759 $ 6,859 Costs of contract revenues—other 2,292 16,102 General and administrative expenses 185 1,189 Loss on sale of assets—net 4,572 4,691 Other expense 2,337 — Total 16,145 28,841

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Operating Lease Payments	Future minimum operating lease payments at December 31, 2018, are as follows: 2019 $ 26,554 2020 22,349 2021 18,430 2022 13,552 2023 9,041 Thereafter 8,697 Total minimum operating lease payments $ 98,623

Business Dispositions (Tables)

Business Dispositions (Tables)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations And Disposal Groups [Abstract]
Schedule of Discontinued Operations	The results of the business have been reported in discontinued operations as follows: 2018 2017 2016 Revenue $ 76,843 $ 112,607 $ 133,637 Loss before income taxes from discontinued operations $ (9,361 ) $ (25,944 ) $ (14,334 ) Preliminary loss on disposal of assets held for sale (14,110 ) — — Income tax benefit 6,162 10,052 5,615 Loss from discontinued operations, net of income taxes $ (17,309 ) $ (15,892 ) $ (8,719 )
Schedule of Major Classes of Assets and Liabilities of Businesses Reported as Discontinued Operations	The major classes of assets and liabilities of businesses reported as discontinued operations are shown below: 2018 2017 Assets: Accounts receivable—net $ 13,943 $ 23,593 Contract revenues in excess of billings 9,971 12,881 Other current assets 865 1,943 Assets held for sale $ 24,779 $ 38,417 Property and equipment—net 6,612 10,369 Goodwill 7,000 7,000 Other intangible assets—net 372 907 Other assets 1,699 2,825 Reserve for loss on disposal (14,110 ) — Assets held for sale—noncurrent $ 1,573 $ 21,101 Liabilities: Accounts payable $ 8,343 $ 22,505 Accrued expenses 4,380 4,292 Other current liabilities 1,217 2,576 Liabilities held for sale 13,940 29,373 Other liabilities 146 773 Liabilities held for sale—noncurrent $ 146 $ 773

Nature of Business and Summar_4

Nature of Business and Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)segment	Jan. 01, 2019USD ($)
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Number of operating Segments | segment	1
Number of reportable segments | segment	1
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	$ 1,950
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Lease assets		$ 80,000
Lease liabilities		$ 90,000

Nature of Business and Summar_5

Nature of Business and Summary of Significant Accounting Policies (Estimated Useful Lives By Class of Assets) (Details)	12 Months Ended
	Dec. 31, 2018
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 - (Computati

Earnings Per Share - (Computations for Basic and Diluted Earnings (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ 11,016	$ (15,368)	$ 542
Loss on discontinued operations, net of income taxes	(17,309)	(15,892)	(8,719)
NET LOSS	$ (6,293)	$ (31,260)	$ (8,177)
Weighted-average common shares outstanding — basic	62,236	61,365	60,744
Effect of stock options and restricted stock units	1,371		623
Weighted-average common shares outstanding — diluted	63,607	61,365	61,367
Earnings (loss) per share from continuing operations — basic	$ 0.18	$ (0.25)	$ 0.01
Earnings (loss) per share from continuing operations — diluted	$ 0.17	$ (0.25)	$ 0.01

Earnings Per Share - (Schedule

Earnings Per Share - (Schedule of Stock Options and Restricted Stock Units Excluded from Diluted Weighted-Average Common Shares) (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017shares
Earnings Per Share [Abstract]
Effect of stock options and restricted stock units	716

Earnings Per Share - (Schedul_2

Earnings Per Share - (Schedule of Stock Options and Restricted Stock Units Excluded from Calculation of Anti-Diluted Earnings Per Share) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Effect of stock options and restricted stock units	1,285	2,476	1,594

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 739,278	$ 810,727
Accumulated depreciation	(369,415)	(413,802)
Property and equipment — net	369,863	396,925
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	5,071	5,071
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	14,087	12,453
Operating Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 710,128	$ 783,211

Property and Equipment (Narrati

Property and Equipment (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation	$ 50,389	$ 55,962	$ 54,826
Operating Equipment [Member]
Property, Plant and Equipment [Line Items]
Operating equipment excluded from property and equipment held for sale		$ 3,537	$ 8,460

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Payroll and employee benefits	$ 15,298	$ 7,658
Insurance	13,724	21,943
Fuel hedge contracts	4,710
Interest	3,448	4,210
Contract reserves	1,709	2,720
Income and other taxes	1,175	1,764
Accrued rent	496	6,519
Other	7,791	7,112
Total accrued expenses	$ 48,351	$ 51,926

Long-Term Debt (Schedule of Lon

Long-Term Debt (Schedule of Long-Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Revolving credit facility	$ 11,500	$ 95,000
Notes payable		13,296
8% senior notes	321,950	321,057
Line of credit, senior note payable, equipment notes payable and senior note	333,450	429,353
Current portion of revolving credit facility	(11,500)
Current portion of notes payable		(1,212)
Long term debt	$ 321,950	$ 428,141

Long-Term Debt (Schedule of L_2

Long-Term Debt (Schedule of Long-Term Debt) (Parenthetical) (Details)	Dec. 31, 2018	May 31, 2017
8.000% Senior Notes Due in 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.00%	8.00%

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($)	Dec. 30, 2016	Feb. 28, 2018	May 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Debt Instrument [Line Items]
Maximum availability of earnings under credit agreement for five consecutive days				$ 31,250,000			$ 31,250,000
Maximum availability of earnings under credit agreement for one day				25,000,000			25,000,000
Revolving credit facility				11,500,000			11,500,000
Letters of credit outstanding				37,749,000			37,749,000
Letter of credit remaining borrowing capacity				174,555,000			174,555,000
Line of credit facility current borrowing capacity				$ 26,196,000			$ 26,196,000
Net proceeds from issuance					$ 325,000,000
Percentage of companies domestic subsidiaries that guaranteed obligation under senior notes				100.00%
Amortization of deferred financing fees				$ 3,504,000	$ 3,280,000	$ 2,438,000
Senior Notes [Member]
Debt Instrument [Line Items]
Face value of senior notes issued, percentage				100.00%			100.00%
Net proceeds from issuance				$ 321,653,000
Vessels and Ancillary Equipment [Member]
Debt Instrument [Line Items]
Net proceeds from sale-leaseback of a vessel yielding		$ 4,500,000
8.000% Senior Notes Due in 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 325,000,000	$ 325,000,000			$ 325,000,000
Debt instrument, interest rate, stated percentage			8.00%	8.00%			8.00%
Maturity date			May 15, 2022	May 15, 2022
7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 275,000,000			$ 275,000,000
Debt instrument, interest rate, stated percentage				7.375%	7.375%		7.375%
Maturity date				Feb. 28, 2019
Redemption of notes				$ 282,638,000			$ 282,638,000
Maximum [Member]
Debt Instrument [Line Items]
Expenses related to buy-out operating leases				$ 20,000,000
Capital expenditures by credit parties							$ 135,000,000
Fixed charge coverage ratio	1.10%
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, 2018USD ($)
Debt Disclosure [Abstract]
2,019	$ 11,500
2,022	325,000
Total	$ 336,500

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, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Net Asset (Liability)	$ 4,710	$ 2,501
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)	$ 4,710	$ 2,501

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) gal in Millions	1 Months Ended	12 Months Ended
	May 31, 2017USD ($)	Dec. 31, 2018USD ($)Contract$ / galgal	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)
Derivatives Fair Value [Line Items]
Derivative underlying hedge percent		80.00%
Derivative, Nonmonetary Notional Amount, Volume | gal		7.8
Fair value hedge liabilities		$ 4,710,000
Fair value hedge assets			$ 2,501,000
Reclassification of derivative (gains) losses to earnings—net of tax		1,569,000	$ 218,000	$ (30,000)
8.000% Senior Notes Due in 2022 [Member]
Derivatives Fair Value [Line Items]
Debt instrument, face amount	$ 325,000,000	$ 325,000,000
Stated interest rate	8.00%	8.00%
Maturity date	May 15, 2022	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		$ 330,281,000
Minimum [Member]
Derivatives Fair Value [Line Items]
Fixed price range | $ / gal		1.91
Maximum [Member]
Derivatives Fair Value [Line Items]
Fixed price range | $ / gal		2.34
Foreign Exchange Contract [Member]
Derivatives Fair Value [Line Items]
Number of outstanding contracts | Contract		0	0

Fair Value Measurements (Sche_2

Fair Value Measurements (Schedule of Fair Value of Fuel Hedge Contracts Balance Sheet Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives Fair Value [Line Items]
Asset derivatives		$ 2,501
Liability derivatives	$ 4,710
Other Current Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Fuel Hedge Contracts [Member]
Derivatives Fair Value [Line Items]
Asset derivatives		$ 2,501
Accrued Expenses [Member] | Derivatives Designated as Hedging Instruments [Member] | Fuel Hedge Contracts [Member]
Derivatives Fair Value [Line Items]
Liability derivatives	$ 4,710

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Cumulative translation adjustments—net of tax	[1]	$ 1,513	$ (41)	$ 508
Reclassification of derivative (gains) losses to earnings—net of tax		(1,569)	(218)	30
Change in fair value of derivatives—net of tax		(3,756)	1,407	300
Net unrealized (gain) loss on derivatives—net of tax	[2]	(5,325)	1,189	330
Other comprehensive income (loss)—net of tax		$ (3,812)	$ 1,148	$ 838
[1]	Net of income tax (provision) benefit of (1,017), $44 and (338) for the years ended December 31, 2018, 2017 and 2016, respectively.
[2]	Net of income tax benefit of $775, $1,048 and $216 for the years ended December 31, 2018, 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments Gain Loss [Line Items]
Other expense	$ (2,590)	$ 11	$ (777)
Costs of contract revenues	509,335	549,429	552,130
Income tax (provision) benefit	(5,437)	33,761	177
Net income (loss)	6,293	31,260	8,177
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Derivative Instruments Gain Loss [Line Items]
Other expense	(2,337)
Income tax (provision) benefit	612
Net income (loss)	(1,725)
Fuel Hedge Contracts [Member] | Accumulated Gain Loss Net Cash Flow Hedge Parent [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Derivative Instruments Gain Loss [Line Items]
Costs of contract revenues	(2,125)	(358)	50
Income tax (provision) benefit	(556)	140	20
Net income (loss)	$ (1,569)	$ (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, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax provision (benefit) from continuing operations	$ 5,437	$ (33,761)	$ (177)
Income tax benefit from discontinued operations	(6,162)	(10,052)	(5,615)
Income tax benefit	$ (725)	$ (43,813)	$ (5,792)

Income Taxes (Income (Loss) fro

Income Taxes (Income (Loss) from Continuing Operations before Income Tax from Domestic and Foreign Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic operations	$ 26,878	$ (12,263)	$ 12,039
Foreign operations	(10,425)	(36,866)	(11,674)
Total income (loss) from continuing operations before income tax	$ 16,453	$ (49,129)	$ 365

Income Taxes (Provision (Benefi

Income Taxes (Provision (Benefit) For Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current federal tax expense (benefit)		$ (248)	$ 260
Deferred federal tax expense (benefit)	$ 3,702	(31,957)	(129)
Current state tax expense (benefit)	48	29	54
Deferred state tax expense (benefit)	1,687	(1,598)	(508)
Current foreign tax expense (benefit)		13	146
Income tax provision (benefit)	$ 5,437	$ (33,761)	$ (177)

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
U.S. federal statutory income tax rate	21.00%	35.00%	35.00%
Reduction in net deferred tax liabilities		$ 15,720,000
Increase in valuation allowance	$ 116,000	1,152,000	$ 821,000
Operating loss carryforwards, subject to expiration	2,876,000
Operating loss carryforwards, subject to carry forward indefinitely	6,657,000
Unrecognized tax benefits	157,000	157,000	$ 157,000	$ 157,000
Amount of unrecognized tax benefits which would have an impact on the effective tax rate	124,000	124,000
Interest and penalties recorded	71,000	53,000
Deferred tax assets valuation allowance	4,786,000	4,294,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards for federal income tax purposes	168,650,000	207,875,000
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	$ 190,901,000	209,877,000
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	2,028
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Loss carryforwards for federal income tax purposes	$ 9,533,000	7,637,000
Valuation allowance for net operating loss carryforwards	$ 2,338,000	$ 1,962,000
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

Income Taxes (Income Tax Bene_2

Income Taxes (Income Tax Benefit Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax provision (benefit) at statutory U.S. federal income tax rate	$ 3,455	$ (17,194)	$ 128
State income tax — net of federal income tax benefit	937	(1,746)	(227)
Impact of Tax Cuts and Job Act		(15,720)
Change in state law regarding NOL carryforwards	658
Nondeductible officer compensation	201
Change in deferred state tax rate			(1,043)
Research and development tax credits	(218)	(170)	(253)
Changes in unrecognized tax benefits	14	10	10
Changes in valuation allowance	116	1,152	821
Other	274	(93)	387
Income tax provision (benefit)	$ 5,437	$ (33,761)	$ (177)

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits — January 1	$ 157	$ 157	$ 157
Gross increases — tax positions in prior period
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, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Accrued liabilities	$ 9,287	$ 8,119
Federal NOLs	35,417	43,654
Foreign NOLs	2,338	1,962
State NOLs	10,796	12,382
Tax credit carryforwards	2,159	1,941
Charitable contribution	910	1,340
Valuation allowance	(4,786)	(4,294)
Total deferred tax assets	56,121	65,104
Depreciation and amortization	(78,967)	(89,966)
Other liabilities		(699)
Total deferred tax liabilities	(78,967)	(90,665)
Net noncurrent deferred tax liabilities	$ (22,846)	$ (25,561)

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 4,643	$ 2,917	$ 2,651
Total unrecognized compensation cost related to non-vested RSUs	4,827
Amount related to shares used for tax withholding obligations	$ 1,205	$ 328
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	156,000	207,000	86,000
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	$ 100
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, 2018USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding as of January 1, 2018 | shares	1,377
Exercised | shares	(62)
Forfeited or Expired | shares	(155)
Outstanding as of December 31, 2018 | shares	1,160
Vested at December 31, 2018 | shares	1,160
Weighted average exercise price outstanding as of January 1, 2018 | $ / shares	$ 6.34
Weighted average exercise price, exercised | $ / shares	4.78
Weighted average exercise price, forfeited or expired | $ / shares	5.60
Weighted average exercise price outstanding as of December 31, 2018 | $ / shares	6.52
Weighted average exercise price, vested at December 31, 2018 | $ / shares	$ 6.52
Weighted average remaining contractual term, outstanding at December 31, 2018	2 years 9 months 18 days
Weighted average remaining contractual term, vested as of December 31, 2018	2 years 9 months 18 days
Aggregate intrinsic value, outstanding as of December 31, 2018 | $	$ 646
Aggregate intrinsic value, vested at December 31, 2018 | $	$ 646

Share-Based Compensation (Sum_2

Share-Based Compensation (Summary of Non-Vested Restricted Stock Units) (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding as of January 1, 2018 | shares	2,196
Options granted | shares	2,051
Options vested | shares	(758)
Options forfeited | shares	(501)
Options outstanding as of December 31, 2018 | shares	2,988
Options expected to vest at December 31, 2018 | shares	2,084
Weighted-average grant-date fair value as of January 1, 2018 | $ / shares	$ 5.06
Weighted-average grant-date fair value, granted | $ / shares	4.83
Weighted-average grant-date fair value, vested | $ / shares	4.95
Weighted-average grant-date fair value, forfeited | $ / shares	5.44
Weighted-average grant-date fair value as of December 31, 2018 | $ / shares	4.88
Weighted-average grant-date fair value, expected to vest at December 31, 2018 | $ / shares	$ 4.63

Revenue (Summary of Impact of C

Revenue (Summary of Impact of Change in Accounting Principle on Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Contract revenues in excess of billings	$ 17,953	$ 77,907
Other current assets	31,907	38,605
Other	10,760	13,088
LIABILITIES AND EQUITY
Accrued expenses	(48,351)	(51,926)
Billings in excess of contract revenues	17,793	2,586
Deferred taxes	(22,846)	(25,561)
Accumulated deficit	(74,971)	$ (67,101)
ASU 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
ASSETS
Contract revenues in excess of billings	(18,334)
Other current assets	8,953
Other	4,176
LIABILITIES AND EQUITY
Accrued expenses	(5,306)
Billings in excess of contract revenues	5,834
Deferred taxes	(1,468)
Accumulated deficit	$ (4,265)

Revenue (Summary of Impact of_2

Revenue (Summary of Impact of Change in Accounting Principle on Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Contract revenues	$ 620,795	$ 592,159	$ 637,468
Type of Revenue [Extensible List]	gldd:ContractMember	gldd:ContractMember	gldd:ContractMember
Costs of contract revenues	$ 509,335	$ 549,429	$ 552,130
Type of Cost, Good or Service [Extensible List]	gldd:ContractMember	gldd:ContractMember	gldd:ContractMember
Income tax provision (benefit) from continuing operations	$ 5,437	$ (33,761)	$ (177)
Loss from continuing operations	11,016	(15,368)	542
Net loss	(6,293)	(31,260)	(8,177)
Comprehensive loss	(10,105)	$ (30,112)	$ (7,339)
ASU 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Contract revenues	$ (14,696)
Type of Revenue [Extensible List]	gldd:ContractMember
Costs of contract revenues	$ (11,360)
Type of Cost, Good or Service [Extensible List]	gldd:ContractMember
Income tax provision (benefit) from continuing operations	$ 867
Loss from continuing operations	(2,469)
Net loss	(2,469)
Comprehensive loss	$ (2,469)

Revenue (Narrative) (Details)

Revenue (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenue From Contract With Customer [Line Items]
Revenue, remaining performance obligation	$ 707,091
Percentage of performance obligation to be recognized as revenue	76.00%
Performance obligation, expected to be recognized as revenue year	2,019
Remaining performance obligation, expected timing of satisfaction, year	2,020
Revenue, description of timing	one year or less
Contract revenues	$ 620,795	$ 592,159	$ 637,468
Amortization on pre-construction costs	15,411
Long-lived assets, net book value	30,601	47,563
Other Current and Noncurrent Assets [Member]
Revenue From Contract With Customer [Line Items]
Costs to fulfill contracts with customers recognized as an asset	13,129			$ 6,754
Foreign [Member]
Revenue From Contract With Customer [Line Items]
Contract revenues	$ 14,088	$ 42,306	$ 59,413
Dredging [Member] | Sales [Member] | Federal Government Agencies [Member] | Customer Concentration Risk [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	75.50%	63.40%	64.30%
Dredging [Member] | Accounts Receivable [Member] | Federal Government Agencies [Member] | Customer Concentration Risk [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	65.30%	42.80%
Dredging [Member] | Foreign [Member]
Revenue From Contract With Customer [Line Items]
Contract revenues	$ 14,088	$ 42,306	$ 59,413
Dredging [Member] | Middle East [Member] | Sales [Member] | Geographic Concentration Risk [Member] | Maximum [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	10.00%	10.00%	10.00%
Dredging [Member] | Middle East [Member] | Accounts Receivable [Member] | Geographic Concentration Risk [Member] | Maximum [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	10.00%

Revenue (Summary of Type of Wor

Revenue (Summary of Type of Work, Contract Revenues) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Contract revenues	$ 620,795	$ 592,159	$ 637,468
Type of Work [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	620,795	592,159	637,468
Type of Work [Member] | Dredging [Member] | Capital-U.S. [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	333,037	185,113	219,914
Type of Work [Member] | Dredging [Member] | Capital-Foreign [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	14,088	42,306	59,413
Type of Work [Member] | Dredging [Member] | Coastal Protection [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	175,923	191,070	215,041
Type of Work [Member] | Dredging [Member] | Maintenance [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	53,427	134,923	92,274
Type of Work [Member] | Dredging [Member] | Rivers & Lakes [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	$ 44,320	$ 38,747	$ 50,826

Revenue (Summary of Type of Cus

Revenue (Summary of Type of Customer, Contract Revenues) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Contract revenues	$ 620,795	$ 592,159	$ 637,468
Foreign [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	14,088	42,306	59,413
Type of Customer [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	620,795	592,159	637,468
Type of Customer [Member] | Federal Government [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	468,421	375,276	409,941
Type of Customer [Member] | State and Local Government [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	93,499	145,196	126,395
Type of Customer [Member] | Private [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	44,787	29,381	41,719
Type of Customer [Member] | Foreign [Member]
Disaggregation Of Revenue [Line Items]
Contract revenues	$ 14,088	$ 42,306	$ 59,413

Revenue (Schedule of Accounts R

Revenue (Schedule of Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Completed contracts	$ 8,592	$ 10,658
Contracts in progress	48,418	28,212
Retainage	7,969	17,545
Accounts receivable, gross	64,979	56,415
Allowance for doubtful accounts	(200)
Total accounts receivable—net	64,779	56,415
Accounts receivable—net	$ 64,779	51,940
Long-term accounts receivable and retainage		$ 4,475

Revenue (Components of Contract

Revenue (Components of Contracts in Progress) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Costs and earnings in excess of billings for contracts in progress	$ 16,137	$ 55,208
Costs and earnings in excess of billings for completed contracts	3,928	22,699
Total contract revenues in excess of billings	20,065	77,907
Contract revenues in excess of billings	17,953	77,907
Long-term contract revenues in excess of billings	2,112
Total billings in excess of contract revenues	(17,793)	(2,586)
Costs And Earnings In Excess Of Billings [Member]
Accounts Notes And Loans Receivable [Line Items]
Costs and earnings for contracts in progress	433,093	507,037
Amounts billed	(416,956)	(451,829)
Costs and earnings for contracts in progress	(433,093)	(507,037)
Billings In Excess Of Costs And Earnings [Member]
Accounts Notes And Loans Receivable [Line Items]
Costs and earnings for contracts in progress	(242,898)	(299,202)
Amounts billed	(260,691)	(301,788)
Costs and earnings for contracts in progress	$ 242,898	$ 299,202

Revenue (Summary of Gross Profi

Revenue (Summary of Gross Profit from Foreign Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
CONTRACT REVENUES	$ 620,795	$ 592,159	$ 637,468
Costs of contract revenues	(509,335)	(549,429)	(552,130)
GROSS PROFIT	111,460	42,730	85,338
Foreign [Member]
Disaggregation Of Revenue [Line Items]
CONTRACT REVENUES	14,088	42,306	59,413
Costs of contract revenues	(19,866)	(73,958)	(66,729)
GROSS PROFIT	$ (5,778)	$ (31,652)	$ (7,316)

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)item	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Defined Contribution Plan Disclosure [Line Items]
Number of sponsored 401(k) plans | item	2
Expense for matching and discretionary contributions	$ 5,060	$ 2,616	$ 2,686
Contributes to various multiemployer pension plans	$ 4,207	$ 4,699	$ 4,793
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Multiemployer plans collective-bargaining arrangement percentage of contributions	5.00%

Restructuring Charges (Narrativ

Restructuring Charges (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Accrued severance expense	$ 662	$ 1,403
Severance [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charges		3,549
Asset Retirements [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charges		32,309
Pre-contract Costs [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charges		6,441
Closeout Costs [Member]
Restructuring Cost And Reserve [Line Items]
Estimated restructuring charges		$ 4,194

Restructuring Charges (Schedule

Restructuring Charges (Schedule of Restructuring Charges) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 16,145	$ 28,841
Costs of Contract Revenues - Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	6,759	6,859
Costs of Contract Revenues - Other [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	2,292	16,102
General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	185	1,189
Loss on Sale of Assets—Net [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	4,572	4,691
Other Expense [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 2,337	$ 0

Commitments and Contingencies_2

Commitments and Contingencies (Narrative) (Details) - USD ($)	Feb. 28, 2017	Jan. 14, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2017
Commitments And Contingencies [Line Items]
Outstanding performance bonds			$ 1,389,239,000
Revenue value remaining from outstanding performance bonds			619,426,000
Proceeds from Legal Settlements		$ 5,309,000
Rent expense under long term operating lease arrangements			21,160,000	$ 26,664,000	$ 20,006,000
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			78,314,000
Minimum [Member]
Commitments And Contingencies [Line Items]
Bids bond range			$ 1,000,000
Warranty periods			1 year
Loss contingency, Estimate of possible loss			$ 200,000
Maximum [Member]
Commitments And Contingencies [Line Items]
Bids bond range			$ 10,000,000
Warranty periods			3 years
Loss contingency, Estimate of possible loss			$ 250,000

Commitments and Contingencies_3

Commitments and Contingencies (Future Minimum Operating Lease Payments) (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,019	$ 26,554
2,020	22,349
2,021	18,430
2,022	13,552
2,023	9,041
Thereafter	8,697
Total minimum operating lease payments	$ 98,623

Related Party Transactions (Det

Related Party Transactions (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2017Property	Dec. 31, 2018USD ($)Facility	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Related Party Transaction [Line Items]
Rent expense		$ 21,160	$ 26,664	$ 20,006
Number of properties sold to a non-related party | Property	1
Terra Contracting LLC [Member]
Related Party Transaction [Line Items]
Rent expense				195
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		$ 222	$ 263	$ 506
Number of facilities owned by former owner | Facility		2

Business Dispositions (Narrativ

Business Dispositions (Narrative) (Details) - USD ($) $ in Thousands	Feb. 28, 2017	Apr. 23, 2014	Dec. 31, 2018	Dec. 31, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision to reduce net assets, discontinued operation			$ 14,110
Estimated surety bond claim, including associated expenses				$ 20,900
Surety Bond [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Aggregate demolition surety performance bond	$ 20,000
NASDI, LLC and Yankee Environmental Services, LLC
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses		$ 5,309

Business Dispositions - (Schedu

Business Dispositions - (Schedule of Discontinued Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Discontinued Operation Income Loss From Discontinued Operation Disclosures [Abstract]
Revenue	$ 76,843	$ 112,607	$ 133,637
Loss before income taxes from discontinued operations	(9,361)	(25,944)	(14,334)
Preliminary loss on disposal of assets held for sale	(14,110)
Income tax benefit	6,162	10,052	5,615
Loss from discontinued operations, net of income taxes	$ (17,309)	$ (15,892)	$ (8,719)

Business Dispositions - (Sche_2

Business Dispositions - (Schedule of Major Classes of Assets and Liabilities of Businesses Reported as Discontinued Operations ) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Accounts receivable—net	$ 13,943	$ 23,593
Contract revenues in excess of billings	9,971	12,881
Other current assets	865	1,943
Assets held for sale	24,779	38,417
Property and equipment—net	6,612	10,369
Goodwill	7,000	7,000
Other intangible assets—net	372	907
Other assets	1,699	2,825
Reserve for loss on disposal	(14,110)
Assets held for sale—noncurrent	1,573	21,101
Liabilities:
Accounts payable	8,343	22,505
Accrued expenses	4,380	4,292
Other current liabilities	1,217	2,576
Liabilities held for sale	13,940	29,373
Other liabilities	146	773
Liabilities held for sale—noncurrent	$ 146	$ 773

Schedule II-Valuation and Qua_2

Schedule II-Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 4,294	$ 7,391	$ 6,679
Additions	692	1,152	1,032
Deductions		(4,249)	(320)
Ending Balance	4,986	4,294	7,391
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance		258	578
Additions	200
Deductions		(258)	(320)
Ending Balance	200		258
Valuation Allowance for Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	4,294	7,133	6,101
Additions	492	1,152	1,032
Deductions		(3,991)
Ending Balance	$ 4,786	$ 4,294	$ 7,133