Willbros 10-K 30 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 26, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	WG
Entity Registrant Name	Willbros Group, Inc.\NEW\
Entity Central Index Key	1,449,732
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		63,221,610
Entity Public Float			$ 127,979,239

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 33,472	$ 41,420
Accounts receivable, net	142,192	112,037
Contract cost and recognized income not yet billed	13,992	11,938
Prepaid expenses and other current assets	20,760	18,416
Parts and supplies inventories	1,152	800
Assets held for sale	1,804	9,050
Assets associated with discontinued operations	324	505
Total current assets	213,696	194,166
Property, plant and equipment, net	30,113	38,123
Intangible assets, net	67,181	76,848
Restricted cash	40,367	40,206
Deferred income taxes	0	315
Other long-term assets	12,520	13,378
Total assets	363,877	363,036
Current liabilities:
Accounts payable and accrued liabilities	138,161	83,488
Contract billings in excess of cost and recognized income	17,814	4,938
Current maturities of long-term debt	105,175	0
Short-term borrowings under revolving credit facility	28,108	0
Accrued income taxes	310	311
Other current liabilities	6,056	6,253
Total current liabilities	297,580	104,843
Long-term debt obligations	0	89,189
Long-term liabilities for unrecognized tax benefits	603	0
Other long-term liabilities	33,093	32,872
Long-term liabilities associated with discontinued operations	893	995
Total liabilities	332,169	227,899
Contingencies and commitments (Note 15)
Stockholders’ equity:
Preferred stock, par value $.01 per share, 1,000,000 shares authorized, none issued	0	0
Common stock, par value $.05 per share, 105,000,000 shares authorized and 65,598,065 shares issued at December 31, 2017 (64,679,896 at December 31, 2016)	3,271	3,226
Additional paid-in capital	752,117	749,303
Accumulated deficit	(706,116)	(598,021)
Treasury stock at cost, 2,361,343 shares at December 31, 2017 (2,025,208 at December 31, 2016)	(15,702)	(15,137)
Accumulated other comprehensive loss	(1,862)	(4,234)
Total stockholders’ equity	31,708	135,137
Total liabilities and stockholders’ equity	363,877	363,036
Liabilities held for sale
Current liabilities:
Liabilities held for sale	865	8,275
Current liabilities associated with discontinued operations
Current liabilities:
Liabilities held for sale	$ 1,091	$ 1,578

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in USD per share)	$ 0.05	$ 0.05
Common stock, shares authorized	105,000,000	105,000,000
Common stock, shares issued	65,598,065	64,679,896
Treasury stock, shares	2,361,343	2,025,208

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Contract revenue	$ 849,983	$ 731,685	$ 908,994
Contract costs	874,738	685,389	868,240
Contract income (loss)	(24,755)	46,296	40,754
Amortization of intangibles	9,667	9,754	9,874
General and administrative	54,693	60,993	77,335
Gain on sale of subsidiary	0	0	(12,826)
Other charges	2,226	6,210	18,469
Operating loss	(91,341)	(30,661)	(52,098)
Interest expense	(16,017)	(13,976)	(27,254)
Interest income	31	451	51
Debt covenant suspension and extinguishment charges	0	(63)	(39,178)
Other, net	(296)	(63)	(101)
Total other income (expense)	(16,282)	(13,651)	(66,482)
Loss from continuing operations before income taxes	(107,623)	(44,312)	(118,580)
Benefit for income taxes	(964)	(530)	(54,031)
Loss from continuing operations	(106,659)	(43,782)	(64,549)
Income (loss) from discontinued operations, net of provision for income taxes	(1,436)	(3,977)	96,032
Net income (loss)	$ (108,095)	$ (47,759)	$ 31,483
Basic income (loss) per share attributable to Company shareholders:
Loss from continuing operations (in dollar per share)	$ (1.72)	$ (0.71)	$ (1.12)
Income (loss) from discontinued operations (in dollar per share)	(0.02)	(0.06)	1.66
Net income (loss) (in dollar per share)	(1.74)	(0.77)	0.54
Diluted income (loss) per share attributable to Company shareholders:
Loss from continuing operations (in dollar per share)	(1.72)	(0.71)	(1.12)
Income (loss) from discontinued operations (in dollar per share)	(0.02)	(0.06)	1.66
Net income (loss) (in dollar per share)	$ (1.74)	$ (0.77)	$ 0.54
Weighted average number of common shares outstanding:
Basic (in shares)	62,160,849	61,364,592	57,759,988
Diluted (in shares)	62,160,849	61,364,592	57,759,988

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (108,095)	$ (47,759)	$ 31,483
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	1,287	553	(8,828)
Changes in derivative financial instruments	1,085	1,222	31
Total other comprehensive income (loss), net of tax	2,372	1,775	(8,797)
Total comprehensive income (loss)	$ (105,723)	$ (45,984)	$ 22,686

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Total Stock- holders’ Equity Willbros Group, Inc.	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest
Beginning balance at Dec. 31, 2014	$ 113,825	$ 113,536	$ 2,597	$ 703,728	$ (581,745)	$ (13,832)	$ 2,788	$ 289
Beginning balance, shares at Dec. 31, 2014			52,094,931
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	31,483	31,483			31,483			0
Foreign currency translation adjustments, net of tax	(8,828)	(8,828)					(8,828)
Derivatives, net of tax	31	31					31
Sale of noncontrolling interest	(289)							(289)
Cost of debt covenant suspension	33,515	33,515	$ 506	33,009	0	0	0	0
Cost of debt covenant suspension, shares			10,125,410
Amortization of stock-based compensation	8,562	8,562		8,562
Stock issued under share-based compensation plans			$ 85	(85)
Stock issued under share-based compensation plans, shares			1,697,879
Additions to treasury stock, vesting and forfeitures of restricted stock	(899)	(899)				(899)
Ending balance at Dec. 31, 2015	177,400	177,400	$ 3,188	745,214	(550,262)	(14,731)	(6,009)	0
Ending balance, shares at Dec. 31, 2015			63,918,220
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(47,759)	(47,759)			(47,759)			0
Foreign currency translation adjustments, net of tax	553	553					553
Derivatives, net of tax	1,222	1,222					1,222
Amortization of stock-based compensation	4,127	4,127		4,127
Stock issued under share-based compensation plans			$ 38	(38)
Stock issued under share-based compensation plans, shares			761,676
Additions to treasury stock, vesting and forfeitures of restricted stock	(406)	(406)				(406)
Ending balance at Dec. 31, 2016	135,137	135,137	$ 3,226	749,303	(598,021)	(15,137)	(4,234)	0
Ending balance, shares at Dec. 31, 2016			64,679,896
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(108,095)	(108,095)			(108,095)
Foreign currency translation adjustments, net of tax	1,287	1,287					1,287
Derivatives, net of tax	1,085	1,085					1,085
Amortization of stock-based compensation	2,859	2,859		2,859
Stock issued under share-based compensation plans			$ 45	(45)
Stock issued under share-based compensation plans, shares			918,169
Additions to treasury stock, vesting and forfeitures of restricted stock	(565)	(565)				(565)
Ending balance at Dec. 31, 2017	$ 31,708	$ 31,708	$ 3,271	$ 752,117	$ (706,116)	$ (15,702)	$ (1,862)	$ 0
Ending balance, shares at Dec. 31, 2017			65,598,065

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (108,095)	$ (47,759)	$ 31,483
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
(Income) loss from discontinued operations	1,436	3,977	(96,032)
Depreciation and amortization	19,162	21,919	27,200
Stock-based compensation	2,859	4,127	6,605
Debt covenant suspension and extinguishment charges	0	63	39,178
Provision (benefit) for deferred income taxes	326	(176)	(413)
Amortization of debt issue costs	2,203	1,063	573
Non-cash interest expense	2,481	2,173	0
(Gain) loss on disposal of equipment	(3,241)	(3,436)	1,155
Impairment of intangible assets	0	0	534
Gain on sale of subsidiary	0	0	(12,826)
Provision for bad debt	887	284	2,945
Changes in operating assets and liabilities:
Accounts receivable, net	(30,353)	21,182	104,620
Contract cost and recognized income not yet billed	(1,927)	8,411	9,672
Prepaid expenses and other current assets	(2,240)	1,093	(433)
Accounts payable and accrued liabilities	53,101	(20,557)	(56,894)
Accrued income taxes	(1)	(2,818)	715
Contract billings in excess of cost and recognized income	12,874	(506)	(4,611)
Assets held for sale	7,302	0	0
Liabilities held for sale	(7,409)	0	0
Other assets and liabilities, net	1,012	(1,032)	(7,462)
Cash provided by (used in) operating activities of continuing operations	(49,623)	(11,992)	46,009
Cash used in operating activities of discontinued operations	(1,844)	(7,619)	(50,204)
Cash used in operating activities	(51,467)	(19,611)	(4,195)
Cash flows from investing activities:
Proceeds from sale of property, plant and equipment	4,242	6,985	12,228
Proceeds from sale of subsidiaries	950	12,646	236,112
Purchases of property, plant and equipment	(2,450)	(3,794)	(2,705)
Changes in restricted cash	(161)	(4,994)	(35,212)
Cash provided by investing activities of continuing operations	2,581	10,843	210,423
Cash used in investing activities of discontinued operations	0	0	(590)
Cash provided by investing activities	2,581	10,843	209,833
Cash flows from financing activities:
Proceeds from term loan issuance	15,000	0	0
Proceeds from revolver and notes payable	28,995	0	30,439
Payments on capital leases	0	(469)	(915)
Payments on revolver and notes payable	(1,009)	0	(30,439)
Payments on term loan facility	0	(3,128)	(174,648)
Payments to reacquire common stock	(565)	(406)	(899)
Cost of debt issuance	(2,306)	(4,612)	(804)
Cash provided by (used in) financing activities of continuing operations	40,115	(8,615)	(177,266)
Cash provided by financing activities of discontinued operations	0	0	10,624
Cash provided by (used in) financing activities	40,115	(8,615)	(166,642)
Effect of exchange rate changes on cash and cash equivalents	823	(29)	(3,437)
Cash provided by (used in) all activities	(7,948)	(17,412)	35,559
Cash and cash equivalents of continuing operations at beginning of period	41,420	58,832	22,565
Cash and cash equivalents of discontinued operations at beginning of period	0	0	708
Cash and cash equivalents at beginning of period	41,420	58,832	23,273
Cash and cash equivalents at end of period	33,472	41,420	58,832
Less: cash and cash equivalents of discontinued operations at end of period	0	0	0
Cash and cash equivalents of continuing operations at end of period	33,472	41,420	58,832
Supplemental disclosures of cash flow information:
Cash paid for interest (including discontinued operations)	10,783	9,019	28,198
Cash paid for income taxes (including discontinued operations)	993	2,737	3,495
Supplemental non-cash investing and financing transactions:
Capital expenditure included in accounts payable and accrued liabilities	$ 283	$ 171	$ 163

Company Description and Financi

Company Description and Financial Condition	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Company Description and Financial Condition	Company Description and Financial Condition Company Description – Willbros Group, Inc., a Delaware corporation, and its subsidiaries (the “Company,” “Willbros” or “WGI”), is a specialty energy infrastructure contractor serving the oil and gas and power industries with offerings that primarily include construction, maintenance and facilities development services. The Company’s principal markets for continuing operations are the United States and Canada. The Company obtains its work through competitive bidding and negotiations with prospective clients. Contract values range from several thousand dollars to several hundred million dollars, and contract durations range from a few weeks to more than two years. Business Segments – The Company has three reportable segments: Utility T&D , Canada and Oil & Gas . The Company’s Utility T&D segment provides a wide range of services in electric and natural gas transmission and distribution, including comprehensive engineering, procurement, maintenance and construction, repair and restoration of utility infrastructure. These services include engineering, design, installation, maintenance, procurement and repair of electrical transmission, distribution, substation, wireless and gas distribution systems. The Company’s Utility T&D segment conducts projects ranging from small engineering and consulting projects to multi-million dollar turnkey distribution, substation and transmission line projects, including those required for renewable energy facilities. The Company’s Canada segment provides construction, maintenance and fabrication services, including integrity and supporting civil work, pipeline construction, general mechanical and facility construction, American Petroleum Institute (“API”) storage tanks, general and modular fabrication, along with electrical and instrumentation projects serving the Canadian energy and water industries. The Company’s Oil & Gas segment provides construction, maintenance and lifecycle extension services to the midstream markets. These services include facilities construction such as tank terminals, pump stations, flow stations, gas compressor stations and metering stations, as well as small-diameter midstream pipeline construction, integrity construction, system maintenance, tank services and mainline pipeline construction. On January 2, 2018, the Company sold its tank services business to ATS Group, Inc. (“ATS”). See Note 5 – Assets Held for Sale for more information. On January 9, 2018, the Company agreed to sell assets comprising its mainline pipeline construction business to WB Pipeline, LLC, an affiliate of Meridien Energy, LLC. (“Meridien”). Discontinued Operations – On November 30, 2015, the Company sold the balance of its Professional Services segment to TRC Companies (“TRC”). As such, the Professional Services segment, including Willbros Engineers, LLC and Willbros Heater Services, LLC (collectively “Downstream Professional Services”), Premier Utility Services, LLC (“Premier”) and UtilX Corporation (“UtilX”), which were sold earlier in 2015, are presented as discontinued operations in the Company’s Consolidated Financial Statements . These subsidiaries, coupled with assets comprising the Company’s Hawkeye business that was sold in 2013 (“Hawkeye”), are referred to as the “Discontinued Operations.” Assets and liabilities related to the Discontinued Operations are included in the line item “Assets associated with discontinued operations,” “Current liabilities associated with discontinued operations” and “Long-term liabilities associated with discontinued operations” on the Consolidated Balance Sheets for all periods presented. The results of the Discontinued Operations are included in the line item “Income (loss) from discontinued operations, net of provision for income taxes” on the Consolidated Statements of Operations for all periods presented. See Note 18 – Discontinued Operations for more information. Merger Agreement – On March 27, 2018, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Primoris Services Corporation (“Primoris”) and Waco Acquisition Vehicle, Inc., a wholly-owned subsidiary of Primoris (the “Merger Sub”). Pursuant to the Merger Agreement, Merger Sub will be merged into the Company, and the Company will become a wholly owned subsidiary of Primoris. The Merger Agreement includes customary representations, warranties and covenants. Primoris will pay $0.60 per share for all of the Company’s outstanding common stock. The Merger Agreement is expected to close in the second quarter of 2018, subject to satisfaction of customary closing conditions, including approval of the Merger Agreement by the requisite vote of the Company’s stockholders. Upon termination of the Merger Agreement in certain circumstances, the Company is obligated to pay Primoris a termination fee of $4.3 million and, in certain other circumstances, a termination fee of $8.0 million . Term Forbearance Agreement – On March 27, 2018, the Company entered into a Forbearance Agreement (the “Term Forbearance Agreement”) with the lenders under the 2014 Term Credit Agreement (the “Term Lenders”). Under the Term Forbearance Agreement, the Term Lenders agreed to, among other things, forbear from taking any action to enforce certain of their rights or remedies under the 2014 Term Credit Agreement with respect to certain defaults and events of default (the “Term Specified Defaults”). The Term Forbearance Agreement is effective until the earliest of (i) August 15, 2018 or the closing of the Merger Agreement or (ii) the occurrence of any one of several specified termination events including, among other things, the termination of the Merger Agreement (the “Term Forbearance Period”). The effectiveness of the Term Forbearance Agreement is conditioned on the occurrence of several events, including the execution of the Merger Agreement and the Seventh Amendment. Upon expiration of the Term Forbearance Agreement or if the Company were to default under the Term Forbearance Agreement or the 2014 Term Credit Agreement, other than Term Specified Defaults, the Term Lenders would be free to exercise any rights and remedies with respect to such defaults and events of defaults pursuant to the terms of the 2014 Term Credit Agreement. ABL Forbearance Agreement – On March 27, 2018, the Company entered into a Limited Forbearance Agreement (the “ABL Forbearance Agreement”) with the lenders under the 2013 ABL Credit Facility (the “ABL Lenders”). Under the ABL Forbearance Agreement, the ABL Lenders agreed to, among other things, forbear from taking any action to enforce certain of their rights or remedies under the 2013 ABL Credit Facility with respect to certain defaults and events of default (the “ABL Specified Defaults”). The ABL Forbearance Agreement is effective until the earliest of (i) July 31, 2018 or the closing of the Merger Agreement or (ii) the occurrence of any one of several specified termination events including, among other things, the termination of the Merger Agreement (the “ABL Forbearance Period”). The effectiveness of the ABL Forbearance Agreement is conditioned on the occurrence of several events, including the execution of the Merger Agreement and the Seventh Amendment. Upon expiration of the ABL Forbearance Agreement or if the Company were to default under the ABL Forbearance Agreement or the 2013 ABL Credit Facility, other than ABL Specified Defaults, the ABL Lenders would be free to exercise any rights and remedies with respect to such defaults and events of defaults pursuant to the terms of the 2013 ABL Credit Facility. Seventh Amendment to the 2014 Term Credit Agreement – On March 27, 2018, (the “Seventh Amendment Effective Date”), the Company amended the 2014 Term Credit Agreement pursuant to a Seventh Amendment among the Company, as borrower, the guarantors from time to time party thereto, Primoris as initial first-out lender, the lenders from time to time party thereto and Cortland Capital Market Services LLC, as administrative agent (the “Seventh Amendment”). Under the terms of the Seventh Amendment, Primoris will provide the Company with an additional term loan in an amount equal to $10.0 million (the “Initial First-Out Loan”) to be drawn in full no earlier than three business days after the Seventh Amendment Effective Date. The Initial First-Out Loan is subject to various terms and conditions including that no defaults shall have occurred and be continuing under the 2013 ABL Credit Facility or the 2014 Term Credit Agreement other than ABL Specified Defaults and Term Specified Defaults. In addition, under the terms of the Seventh Amendment, Primoris may provide the Company with additional term loans in an aggregate amount not to exceed $10.0 million (the “Additional First-Out Loans”). Interest payable with respect to the Initial First-Out Loan and any Additional First-Out Loans will be paid in-kind through additions to the principal amount of such loans. The Seventh Amendment further provides that, until the termination of the Term Forbearance Period, the due date of any payments due and owing to the lenders (other than Primoris) under the 2014 Term Credit Agreement will be deferred until the fifth business day after the date of the termination of the Term Forbearance Period. In addition, the Seventh Amendment provides that the payment by the borrower of an amount equal to $100.0 million plus the expenses of the administrative agent in an amount not to exceed $1.1 million shall constitute payment in full and satisfaction and discharge of all obligations of the borrower and the other loan parties under the 2014 Term Credit Agreement, but solely if such payment is made in connection with the consummation of the merger. Going Concern – The Company has incurred significant operating losses, cash outflows from operating activities and a net working capital deficiency. The Company does not expect to be in compliance with the Maximum Total Leverage Ratio and Minimum Interest Coverage Ratio under the 2014 Term Credit Agreement beginning with the quarterly period ending March 31, 2018, primarily due to these significant operating losses in 2017. In addition, the Company is not in compliance with certain other provisions under the 2014 Term Credit Agreement and the 2013 ABL Credit Facility, which expires on August 7, 2018. Absent the temporary forbearance provided under the Term Forbearance Agreement and the ABL Forbearance Agreement, all of the Company’s debt obligations would become due under the default provisions in the 2014 Term Credit Agreement and the 2013 ABL Credit Facility. In addition, these significant operating losses and cash outflows have put a considerable strain on the Company’s overall liquidity. Although the Seventh Amendment provides the Company with additional short-term liquidity for the period between the signing of the Merger Agreement and the completion of the merger, the Company can provide no assurance that the merger will be completed. If the Company is unable to complete the merger, it will likely need to explore other strategic alternatives, which could include seeking protection under the U.S. Bankruptcy laws. The Company’s continuing failure to comply with financial covenants and other covenants, its inability to extend or refinance the 2013 ABL Credit Facility and its continuing liquidity issues raise substantial doubt about its ability to continue as a going concern, notwithstanding the temporary forbearance provided under the Term Forbearance Agreement and the ABL Forbearance Agreement and the short-term liquidity provided by the Seventh Amendment. In consideration of the above facts and circumstances, at December 31, 2017 , the Company has classified all of its debt obligations as current, which has caused its current liabilities to far exceed its current assets since such date. These debt obligations, net of unamortized discount and debt issuance costs, approximate $133.3 million at December 31, 2017 . Sale of Mainline Pipeline Construction Business – On January 9, 2018, the Company entered into an agreement to sell assets comprising our mainline pipeline construction business to Meridien. As part of the agreement, the Company retained the three mainline pipeline construction projects associated with the business through their completion. Two of these projects have reached mechanical completion with an existing letter of credit returned in the first quarter of 2018. The remaining right-of-way restoration and other clean-up activities associated with these projects are expected to be completed by the end of the third quarter of 2018. With respect to the remaining mainline pipeline construction project, in the first quarter of 2018, the Company reached a settlement with the customer to mutually conclude the remaining work. In addition, the settlement releases the Company from further liability at the completion of the project. As such, the Company has withdrawn and released any outstanding change orders or claims associated with the project.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation – The Consolidated Financial Statements of the Company include all of its majority-owned subsidiaries and all of its wholly-owned entities. Inter-company accounts and transactions are eliminated in consolidation. The ownership interest of noncontrolling participants in subsidiaries that are not wholly-owned is included as a separate component of equity. These subsidiaries were sold in 2015. Use of Estimates – The Consolidated Financial Statements are prepared in accordance with generally accepted accounting principles (“GAAP”) in the United States and include certain estimates and assumptions made by management of the Company in the preparation of the Consolidated Financial Statements . These estimates and assumptions relate to the reported amounts of assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenue and expense during the period. Significant items subject to such estimates and assumptions include revenue recognition under the percentage-of-completion method of accounting, including estimates of progress towards completion and estimates of gross profit or loss accrual on contracts in progress; tax accruals and certain other accrued liabilities; quantification of amounts recorded for contingencies; valuation allowances for accounts receivable and deferred income tax assets; and the carrying amount of property, plant and equipment, goodwill and intangible assets. The Company bases its estimates on historical experience and other assumptions that it believes relevant under the circumstances. Actual results could differ from these estimates. Change in Presentation – In the second quarter of 2017, the Company adopted a change in presentation on its Consolidated Statements of Operations in order to present a “Contract income (loss)” line item that is consistent with its peers. “Contract income (loss)” is defined as contract revenue less contract costs (which is inclusive of both direct and indirect costs). Previously reported information has been modified to conform to this new presentation. Commitments and Contingencies – Liabilities for loss contingencies arising from claims, assessments, litigation, fines, penalties and other sources are recorded when management assesses that it is probable that a liability has been incurred and the amount can be reasonably estimated. Recoveries of costs from third parties, which management assesses as being probable of realization, are recorded as “Other long-term assets” in the Consolidated Balance Sheets . Legal costs incurred in connection with matters relating to contingencies are expensed in the period incurred. See Note 15 – Contingencies, Commitments and Other Circumstances for more information. Accounts Receivable – Most of the accounts receivable and contract work in progress are from clients in the oil, gas, refinery, petrochemical and power industries in North America. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. Most contracts require payments as the projects progress or, in certain cases, advance payments. The Company generally does not require collateral, but in most cases can place liens against the property, plant or equipment constructed or terminate the contract if a material default occurs. The allowance for doubtful accounts is the Company’s best estimate of the probable amount of credit losses in the Company’s existing accounts receivable. A considerable amount of judgment is required in assessing the realization of receivables. Relevant assessment factors include the creditworthiness of the customer and prior collection history. Balances over 90 days past due are reviewed individually for collectability. Account balances are charged off against the allowance after all reasonable means of collection are exhausted and the potential for recovery is considered remote. The allowance requirements are based on the most current facts available and are re-evaluated and adjusted on a regular basis and as additional information is received. Inventories – Inventories, consisting primarily of parts and supplies, are stated at the lower of actual cost or market. Parts and supplies are evaluated at least annually and adjusted for excess and obsolescence. No excess or obsolescence allowances existed at December 31, 2017 or 2016 . Intangible Assets – The Company’s intangible assets with finite lives include customer relationships and trade names. The value of customer relationships is estimated using the income approach, specifically the excess earnings method. The excess earnings method consists of discounting to present value the projected cash flows attributable to the customer relationships, with consideration given to customer contract renewals, the importance or lack thereof of existing customer relationships to the Company’s business plan, income taxes and required rates of return. The value of trade names is estimated using the relief-from-royalty method of the income approach. This approach is based on the assumption that in lieu of ownership, a company would be willing to pay a royalty in order to exploit the related benefits of this intangible asset. The Company amortizes intangible assets based upon the estimated consumption of the economic benefits of each intangible asset or on a straight-line basis if the pattern of economic benefits consumption cannot otherwise be reliably estimated. Intangible assets subject to amortization are reviewed for impairment and are tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. For instance, a significant change in business climate or a loss of a significant customer, among other things, may trigger the need for an impairment test of intangible assets. An impairment loss is recognized if the carrying amount of an intangible asset is not recoverable and its carrying amount exceeds its fair value. Property, Plant and Equipment – Property, plant and equipment is stated at cost. Depreciation, including amortization of capital leases, is provided on the straight-line method using estimated lives as follows: Construction equipment 3-20 years Furniture and equipment 3-12 years Buildings 20 years Transportation equipment 3-17 years Marine equipment 10 years Leasehold improvements are amortized on a straight-line basis over the shorter of their economic lives or the lease term. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized within operating expenses in the Consolidated Statements of Operations for the period. Normal repair and maintenance costs are charged to expense as incurred. Significant renewals and betterments are capitalized. The Company depreciates assets based on their estimated useful lives at the time of acquisition using the straight-line method. Depreciation and amortization related to operating activities is included in “Contract costs,” and depreciation and amortization related to general and administrative activities is included in “General and administrative” expense in the Consolidated Statements of Operations . “Contract costs” and “General and administrative” expenses are included within operating expenses in the Consolidated Statements of Operations . Further, amortization of assets under capital lease obligations is included in depreciation expense. Long-lived assets are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If an evaluation is required, the estimated future undiscounted cash flows associated with the asset are compared to the asset’s carrying amount to determine if an impairment of such asset is necessary. This evaluation, as well as an evaluation of our intangible assets, requires the Company to make long-term forecasts of the future revenues and costs related to the assets subject to review. Forecasts require assumptions about demand for the Company’s services and future market conditions. Estimating future cash flows requires significant judgment, and the Company’s projections may vary from the cash flows eventually realized. Future events and unanticipated changes to assumptions could require a provision for impairment in a future period. The effect of any impairment would be to expense the difference between the fair value (less selling costs) of such asset and its carrying value. Such expense would be reflected in earnings. In the fourth quarter of 2017, the Company continued to incur significant operating losses primarily driven by losses on three mainline pipeline construction projects in the Oil & Gas segment. Consequently, the Company does not expect to be in compliance with its Maximum Total Leverage Ratio and Minimum Interest Coverage Ratio under the 2014 Term Credit Agreement beginning with the quarterly period ending March 31, 2018. In addition, these significant operating losses have led to significant negative operating cash flow in recent months, which has a put a considerable strain on the Company’s overall liquidity. These factors, combined with the uncertainty associated with the Company’s ability to obtain covenant relief, extend or refinance its indebtedness and meet its obligations as they become due raises substantial doubt about the Company’s ability to continue as a going concern. See Note 1 – Company Description and Financial Condition for more information. The above information indicates that the carrying amount of long-lived assets (including intangible assets) associated with each of the Company’s asset groups may not be recoverable. As such, the Company has performed an impairment assessment of all long-lived assets (including intangible assets) associated with each of its asset groups under ASC 360, Property, Plant and Equipment. As part of its assessment, the Company determined the estimated future undiscounted cash flows derived from the long-lived assets (including intangible assets) associated with each of its asset groups at December 31, 2017 , based on its best internal projections and the likelihood of various outcomes, which includes bankruptcy and outright sale. Based on its assessment, the Company determined that the estimated future undiscounted cash flows associated with each of its asset groups exceeds the carrying amount of long-lived assets (including intangible assets) associated with each of its asset groups. As such, no impairment to long-lived assets (including intangible assets) was required. However, the occurrence of future events or deteriorating conditions could result in additional impairment assessments subsequent to December 31, 2017 . Revenue – A number of factors relating to the Company’s business affect the recognition of contract revenue. The Company typically structures contracts as unit-price, time and materials, fixed-price or cost plus fixed fee. The Company believes that its operating results should be evaluated over a time horizon during which major contracts in progress are completed and change orders, extra work, variations in the scope of work, cost recoveries and other claims are negotiated and realized. Revenue from unit-price and time and materials contracts is recognized as earned. Revenue for fixed-price and cost plus fixed fee contracts is recognized using the percentage-of-completion method. Under this method, estimated contract income and resulting revenue is generally accrued based on costs incurred to date as a percentage of total estimated costs, taking into consideration physical completion. Total estimated costs, and thus contract income, are impacted by changes in productivity, scheduling, unit cost of labor, subcontracts, materials and equipment. Additionally, external factors such as weather, client needs, client delays in providing permits and approvals, labor availability, governmental regulation and politics may affect the progress of a project’s completion and thus the estimated amount and timing of revenue recognition. Certain fixed-price and cost plus fixed fee contracts include, or are amended to include, incentive bonus amounts, contingent on accomplishing a stated milestone. Revenue attributable to incentive bonus amounts is recognized when the risk and uncertainty surrounding the achievement of the milestone have been removed. The Company does not recognize income on a fixed-price contract until the contract is approximately five to ten percent complete, depending upon the nature of the contract. If a current estimate of total contract cost indicates a loss on a contract, the projected loss is recognized in full when determined. The Company considers unapproved change orders to be contract variations on which the Company has customer approval for scope change, but not for price associated with that scope change. Costs associated with unapproved change orders are included in the estimated cost to complete the contracts and are expensed as incurred. The Company recognizes revenue equal to cost incurred on unapproved change orders when realization of price approval is probable and the amount is estimable. Revenue recognized on unapproved change orders is included in “Contract cost and recognized income not yet billed” on the Consolidated Balance Sheets . Revenue recognized on unapproved change orders is subject to adjustment in subsequent periods to reflect the changes in estimates or final agreements with customers. The Company considers claims to be amounts that the Company seeks or will seek to collect from customers or others for customer-caused changes in contract specifications or design, or other customer-related causes of unanticipated additional contract costs on which there is no agreement with customers on both scope and price changes. Revenue from claims is recognized when agreement is reached with customers as to the value of the claims, which in some instances may not occur until after completion of work under the contract. Costs associated with claims are included in the estimated costs to complete the contracts and are expensed when incurred. The Company’s operating loss for the years ended December 31, 2017 and 2016 was positively impacted by approximately $1.4 million and $7.6 million , respectively, as a result of changes in contract estimates related to projects that were in progress at December 31, 2016 and 2015 . Included in these changes in contract estimates for the year ended December 31, 2017 is a $2.0 million income recovery associated with a claim on a cross-country pipeline project in the Canada segment. These changes in contract estimates are primarily attributed to, among other things, a reduction in estimated costs for certain individually immaterial projects as they progress to completion; the realization of change orders related to work previously performed; and other changes in events, facts and circumstances during the period in which the estimate was revised. Insurance – The Company is insured for workers’ compensation, employer’s liability, auto liability and general liability claims, subject to a deductible of $1.0 million per occurrence. Additionally, the Company’s largest non-union employee-related health care benefit plan is subject to a deductible of $0.3 million per claimant per year. Losses are accrued based upon the Company’s estimates of the ultimate liability for claims incurred (including an estimate of claims incurred but not reported), with assistance from third-party actuaries. For these claims, to the extent insurance coverage is above the deductible amounts, the Company has recorded a receivable reflected in “Other long-term assets” in the Consolidated Balance Sheets . These insurance liabilities are difficult to assess and estimate due to unknown factors, including the severity of an injury, the determination of the Company’s liability in proportion to other parties and the number of incidents not reported. The accruals are based upon known facts and historical trends. Income Taxes – The Financial Accounting Standards Board (“FASB”) standard for income taxes takes into account the differences between financial statement treatment and tax treatment of certain transactions. Deferred tax assets and liabilities are recognized for the expected future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of a change in tax rates due to changes in legislation is recognized as income or expense in the period that includes the enactment date. The ultimate realization of deferred tax assets related to net operating loss carry forwards, including federal and state net operating loss carry forwards, is dependent upon the generation of future taxable income in a particular tax jurisdiction during the periods in which the use of such net operating losses are allowed. The Company considers future taxable income, including the impacts of reversing taxable temporary differences, future forecasted income and available tax planning strategies, when evaluating whether deferred tax assets are more likely than not to be realized prior to expiration. The Company files income tax returns in the United States federal jurisdiction, in various states and in various foreign jurisdictions. The Company is subject to examination for 2008 forward for the United States and the majority of the state jurisdictions and for 2010 forward in Canada. Retirement Plans and Benefits – The Company has a voluntary defined contribution retirement plan for U.S. based employees that is qualified and contributory on the part of the employees. Additionally, the Company is subject to collective bargaining agreements with various unions. As a result, the Company participates with other companies in the unions’ multi-employer pension and other postretirement benefit plans. Stock-Based Compensation – Compensation cost resulting from all share-based payment transactions is recognized in the financial statements measured based on the grant-date fair value of the instrument issued and is recognized over the vesting period. Share-based compensation related to restricted stock and restricted stock units or rights, also described collectively as restricted stock units, is recorded based on the Company’s closing stock price as of the grant date. Awards granted are expensed ratably over the vesting period of the award. Foreign Currency Translation – All significant monetary asset and liability accounts denominated in currencies other than United States dollars are translated into United States dollars at current exchange rates. Translation adjustments are included in “Other comprehensive income (loss), net of tax” in the Company’s Consolidated Statements of Comprehensive Income (Loss) . Revenue and expense accounts are converted at prevailing rates throughout the year. Gains or losses on foreign currency transactions are recorded in income in the period in which they are incurred. Concentration of Credit Risk – The Company has a concentration of customers in the oil and gas and power industries which expose the Company to a concentration of credit risk within a single industry. The Company seeks to obtain advance and progress payments for contract work performed on major contracts. Receivables are generally not collateralized. An allowance for doubtful accounts of $2.8 million and $2.0 million is included within “Accounts receivable, net” on the Consolidated Balance Sheets for the years ended December 31, 2017 and 2016, respectively. Income (Loss) per Common Share – Basic income (loss) per share is calculated by dividing net income (loss), less any preferred dividend requirements, by the weighted-average number of common shares outstanding during the year. Diluted income (loss) per share is calculated by including the weighted average number of all potentially dilutive common shares with the weighted-average number of common shares outstanding. Derivative Financial Instruments – The Company may use derivative financial instruments such as forward contracts, options or other common hedging techniques to mitigate non-U.S. currency exchange risk when the Company is unable to match non-U.S. currency revenue with expense in the same currency. The Company has no forward contracts or options at December 31, 2017 and 2016 . The Company is subject to interest rate risk on its debt and investment of cash and cash equivalents arising in the normal course of business and has previously entered into hedging arrangements from time to time to fix or otherwise limit the interest cost of the variable interest rate borrowings. Cash Equivalents – The Company considers all highly liquid investments with an original maturity of 3 months or less to be cash equivalents. Short-term Investments – The Company may invest a portion of its cash in short-term time deposits, some of which may have early withdrawal penalties. All such deposits have maturity dates that exceed three months . There were no short-term investments outstanding as of December 31, 2017 and 2016 . Accounting Pronouncements Recently Adopted – In March 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-09, which changes how companies account for certain aspects of share-based payment awards to employees, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2016 and interim periods within those annual periods with early adoption permitted. The Company adopted ASU 2016-09 in the first quarter with an effective date of January 1, 2017. The recognition of previously unrecognized windfall tax benefits increased the Company’s deferred tax assets by $1.8 million offset by a related valuation allowance which resulted in a $0 cumulative-effect adjustment, net of tax, on the Company’s Consolidated Balance Sheet as of the beginning of 2017. The amendments within ASU 2016-09 related to the recognition of excess tax benefits and tax shortfalls in the Consolidated Statement of Operations and presentation within the operating section of the Consolidated Statement of Cash Flows were adopted prospectively with no adjustments to prior periods. The Company has elected to account for forfeitures as they occur. The remaining provisions of ASU 2016-09 did not have a material effect on the Company’s Consolidated Financial Statements . Accounting Pronouncements Not Yet Adopted – Revenue Recognition – In May 2014, the FASB issued ASU 2014-09 governing the recognition of revenue from contracts with customers. Under the new standard, a company will recognize revenue when it satisfies a performance obligation by transferring a promised good or service to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods and services. The standard also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. In August 2015, under ASU 2015-14, the FASB deferred the effective date of the standard to December 15, 2017 with early adoption permitted. The standard can be applied on a full retrospective or modified retrospective basis whereby the entity records a cumulative effect of initially applying this update at the date of initial application. Furthermore, in March, April, and May of 2016, the FASB issued ASUs 2016-08, 2016-10, and 2016-12, respectively, which provide practical expedients and clarification in regards to ASU 2014-09. ASU 2016-08 amends and clarifies the principal versus agent considerations under the new revenue recognition standard, which requires determination of whether the nature of a promise is to provide the specified good or service to the customer (that is, the entity is a principal) or to arrange for the good or service to be provided to the customer by another party (that is, the entity is an agent). This determination affects the timing and amount of revenue recognition. ASU 2016-10 clarifies issues related to identifying performance obligations. ASU 2016-12 provides practical expedients and clarification pertaining to the exclusion of sales tax from the measurement of a transaction price, the measurement of noncash consideration, allocation of a transaction price on the basis of all satisfied and unsatisfied performance obligations in a modified contract at transition, and the definition of a completed contract. The effective date of ASUs 2016-08, 2016-10, and 2016-12 is December 15, 2017 with early adoption permitted. Quantitative Disclosures of Directional Effects of Adoption The Company will adopt the new revenue guidance effective January 1, 2018 via the modified retrospective approach, by recognizing the cumulative effect of initially applying the new standard as an increase to the opening balance of retained earnings. Although still under the process of determining the impact, we expect this adjustment to be an immaterial impact to our opening balance of retained earnings as well as net income and earnings per share on an ongoing basis. Qualitative Status of Management’s Implementation Efforts Upon our initial evaluation of ASU 2014-09, there are no material changes in the standard that impact our revenue recognition relating to the allocation and measurement of contract revenues and the timing in which those revenues are recognized. However, the new standard will require a substantial increase in the amount and complexity of disclosures related to revenue recognition. The Company has taken steps to effectively implement the new standard by evaluating a representative sample of contracts with customers to identify the potential impacts that would result from applying the requirements of the standard to the Company’s existing revenue contracts. For most of the contracts entered into, the Company expects there to be a similar number of performance obligations, and in most cases, the Company has determined that the method of revenue recognition for these contracts will remain the same with the Company already considering different elements, such as variable consideration, when evaluating their transaction prices. The Company continues analyzing stand-alone pricing of the obligations as well as the timing related to revenue recognition. Significant judgments were used when concluding on the method of revenue recognition, but, in most cases, the Company determined that over time revenue recognition was appropriate via the percentage-of-completion method, based on time incurred, or as units are produced in accordance with the three over time criteria within ASC 606-10-25-27. However, there were also various industry-specific elements that the Company has identified that will have to be continuously monitored as new contracts are entered into in associated with ASU 2014-09, including uninstalled materials, customer provided materials and other elements. The Company has started to update its current accounting policies to align with revenue recognition practices under the new standard. As part of its evaluation of contracts with customers, the Company is holding regular meetings with key stakeholders across the organization to determine the impacts of the standards on its business processes. Additionally, the Company is evaluating its processes to address risks associated with incorporating these standards, and upon adoption, the Company expects to implement new internal controls related to accounting policies and procedures in order to validate the processes implemented upon adoption and going forward. Various trainings of the Accounting team are also expected to be held to further educate the business when applying some of the significant judgments required as part of the new standard. The Company is continuing to evaluate the future impact and method of adoption of ASU 2014-09 and related amendments on its Consolidated Financial Statements and related disclosures. Accounting Pronouncements Not Yet Adopted – Other – In February 2018, the FASB issued ASU 2018-02, which provides that the stranded tax effects from the Tax Cuts and Jobs Act on the balance of other comprehensive earnings may be reclassified to retained earnings. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with an option to adopt early. We are evaluating the effect of the standard on our Consolidated Financial Statements . In May 2017, the FASB issued ASU 2017-09, which clarifies when a change to the terms or conditions of a share-based payment award should be accounted for as a modification. An entity should account for the effects of a modification unless the fair value, vesting conditions and classification, as an equity instrument or a liability instrument, of the modified award are the same before and after a change to the terms or conditions of the share-based payment award. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company does not expect the new standard to have a material impact on its Consolidated Financial Statements . In November 2016, the FASB issued ASU 2016-18, which requires a reporting entity to include restricted cash and restricted cash equivalents in its cash and cash-equivalent balances presented in the entity’s statement of cash flows. A reconciliation between the statement of financial position and the statement of cash flows must be disclosed when the balance sheet includes more than one line item for cash, cash equivalents, restricted cash and restricted cash equivalents. Transfers between non-restricted and restricted cash should not be presented as cash flow activities in the statement of cash flows. Furthermore, an entity with a material restricted cash balance must disclose information regarding the nature of the restrictions. The standard is effective for annual periods beginning after December 15, 2017, including interim periods within those annual reporting periods. At December 31, 2017 and December 31, 2016 , approximately $40.4 million and $40.2 million , respectively, is recorded as “Restricted cash” on the Company’s Consolidated Balance Sheets . These amounts are primarily composed of eligible pledged cash in the Company’s December 31, 2017 and December 31, 2016 borrowing base calculation. The Company will adopt this standard in the first quarter of 2018. In October 2016, the FASB issued ASU 2016-16, which requires a reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. The new guidance does not apply to intra-entity transfers of inventory, and the income tax consequences from the sale of inventory from one member of a consolidated entity to another will continue to be deferred until the inventory is sold to a third party. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company does not expect the new standard to have any impact on its Consolidated Financial Statements . In August 2016, the FASB issued ASU 2016-15, which provides specific guidance for cash flow classifications of cash payments and receipts to reduce the diversity of treatment of such items. The standard is effective for annual periods beginning after December 15, 2017 and interim periods within those annual periods with early adoption permitted. The Company does not expect the new standard to have a material impact on its Consolidated Financial Statements . In February 2016, the FASB issued ASU 2016-02, which requires companies that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those assets. The standard is effective for interim and annual periods beginning after December 15, 2018. Early adoption is pe

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Accounts Receivable	Accounts Receivable Accounts receivable, net as of December 31, 2017 and 2016 is comprised of the following (in thousands): December 31, 2017 2016 Trade $ 95,923 $ 79,348 Unbilled revenue 22,018 20,447 Contract retention 26,146 12,091 Other receivables 901 2,114 Total accounts receivable 144,988 114,000 Less: allowance for doubtful accounts (2,796 ) (1,963 ) Total accounts receivable, net $ 142,192 $ 112,037 The Company expects all accounts receivable to be collected within one year. The provision for bad debt included in operating expenses in the Consolidated Statements of Operations was $0.9 million , $0.3 million and $2.9 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The balances billed but not paid by customers pursuant to retainage provisions in certain contracts are generally due upon completion of the contracts and acceptance by the customer. Based on the Company’s contract terms in recent years, the majority of the retainage balances at each balance sheet date are expected to be collected within the next 12 months.

Contracts in Progress

Contracts in Progress	12 Months Ended
	Dec. 31, 2017
Contractors [Abstract]
Contracts in Progress	Contracts in Progress Contract cost and recognized income not yet billed on uncompleted contracts arise when recorded revenues for a contract exceed the amounts billed under the terms of the contracts. Contract billings in excess of cost and recognized income arise when billed amounts exceed revenues recorded. Amounts are billable to customers upon various measures of performance, including achievement of certain milestones, completion of specified units or completion of the contract. Contract cost and recognized income not yet billed and related amounts billed as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Cost incurred on contracts in progress $ 445,029 $ 234,544 Recognized income (14,536 ) 28,702 430,493 263,246 Progress billings and advance payments (434,315 ) (256,246 ) $ (3,822 ) $ 7,000 Contract cost and recognized income not yet billed $ 13,992 $ 11,938 Contract billings in excess of cost and recognized income (17,814 ) (4,938 ) $ (3,822 ) $ 7,000 Contract cost and recognized income not yet billed includes $0.5 million and $0.5 million at December 31, 2017 and 2016 , respectively, on completed contracts.

Assets Held For Sale

Assets Held For Sale	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Assets Held For Sale	Assets Held for Sale Components of assets held for sale as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Accounts receivable, net $ 490 $ 7,806 Contract cost and recognized income not yet billed 234 136 Prepaid expenses and other assets 36 61 Parts and supplies inventories 409 468 Property, plant and equipment, net 375 318 Intangible assets, net 260 260 Other long-term assets — 1 Total assets held for sale 1,804 9,050 Accounts payable and accrued liabilities 100 3,789 Contract billings in excess of cost and recognized income 765 4,480 Other current liabilities — 3 Other long-term liabilities — 3 Total liabilities held for sale $ 865 $ 8,275 The Company, as part of its ongoing strategic evaluation, made the decision to offer the sale of its tank services business, which is included in the Company’s Oil & Gas segment, to an outside party. At December 31, 2017, the tank business was classified as held for sale, as it was being actively marketed, expected to sell within one year and measured at the lower of carrying value or fair value less costs to sell. On January 2, 2018, the Company sold its tank services business to ATS for $3.0 million , subject to working capital adjustments. Discontinued Operations The following disposals qualify for discontinued operations treatment with ASU 2014-08, which the Company adopted on January 1, 2015. Professional Services On November 30, 2015, the Company sold the balance of its Professional Services segment to TRC for $130.0 million in cash, subject to working capital and other adjustments. At closing, TRC held back $7.5 million from the purchase price (the “Holdback Amount”) until the Company effects the novation of a customer contract from one of the subsidiaries sold in the transaction to the Company (or obtains written approval of a subcontract of all the work that is the subject of such contract) and obtains certain consents. If such novation, subcontract or consents are not approved by March 15, 2016, TRC would pay the Holdback Amount to the Company. In connection with this transaction, the Company recorded a net gain on sale of $97.0 million during the year ended December 31, 2015. During the year ended December 31, 2016, the Company reached an agreement with TRC on substantially all of the outstanding items related to the sale of the Professional Services segment. As a result, the Company received $4.6 million during the year ended December 31, 2016 in relation to the sale and inclusive of the final settlement of working capital and the Holdback Amount and recorded $2.5 million in charges against the original net gain on sale in relation to working capital and other post-closing adjustments. Certain assets and liabilities associated with one Professional Services contract were retained by the Company and have been excluded from the transaction. In 2015, and prior to the sale of the balance of the Professional Services segment, the Company sold the following three subsidiaries that were historically part of the Professional Services segment. Downstream Professional Services On June 12, 2015, the Company sold all of its issued and outstanding equity of Downstream Professional Services to BR Engineers, LLC for approximately $10.0 million in cash. In connection with this transaction, the Company recorded a net loss on sale of $2.2 million during the year ended December 31, 2015. Premier On March 31, 2015, the Company sold all of its membership units in Premier to USIC Locating Services, LLC for approximately $51.0 million in cash, of which $4.0 million was deposited into an escrow account for a period of up to eighteen months to cover post-closing adjustments and any indemnification obligations of the Company. In connection with this transaction, the Company recorded a net gain on sale of $37.1 million during the year ended December 31, 2015. The Company received $3.7 million as full and final settlement of the outstanding escrow amount during the year ended December 31, 2016. UtilX On March 17, 2015, the Company sold all of its equity interests of UtilX to Novinium, Inc. for approximately $40.0 million in cash, of which $0.5 million was deposited into an escrow account for a period of six months to cover post-closing adjustments and any indemnification obligations of the Company. In the third quarter of 2015, the Company cleared the $0.5 million amount recorded in the escrow account as a post-closing adjustment. As a result of this transaction, the Company recorded a net gain on sale of $20.3 million during the year ended December 31, 2015. Hawkeye In the fourth quarter of 2013, the Company sold certain assets comprising its Hawkeye business to Elecnor Hawkeye, LLC, a subsidiary of Elecnor, Inc. Results of Discontinued Operations Condensed Statements of Operations of the Discontinued Operations for the years ended December 31, 2017 , 2016 and 2015 are as follows (in thousands): Year Ended December 31, 2017 Professional Services Hawkeye Other Total Contract revenue $ 1,006 $ — $ — $ 1,006 Contract costs 831 — — 831 General and administrative 1,219 (197 ) — 1,022 Other charges 525 — — 525 Operating income (loss) (1,569 ) 197 — (1,372 ) Non-operating income (expense) — — — — Pre-tax income (loss) (1,569 ) 197 — (1,372 ) Provision for income taxes 64 — — 64 Income (loss) from discontinued operations $ (1,633 ) $ 197 $ — $ (1,436 ) Year Ended December 31, 2016 Professional Services Hawkeye Other Total Contract revenue $ 2,126 $ — $ — $ 2,126 Contract costs 2,299 — — 2,299 Loss on sale of subsidiary 2,456 — — 2,456 General and administrative 2,633 (313 ) — 2,320 Other income (1,060 ) — — (1,060 ) Operating income (loss) (4,202 ) 313 — (3,889 ) Non-operating income (expense) — — — — Pre-tax income (loss) (4,202 ) 313 — (3,889 ) Provision for income taxes — — 88 88 Income (loss) from discontinued operations $ (4,202 ) $ 313 $ (88 ) $ (3,977 ) Year Ended December 31, 2015 Professional Services Hawkeye Other Total Contract revenue $ 229,482 $ 2,078 $ — $ 231,560 Contract costs 197,414 1,317 — 198,731 Amortization of intangibles 793 — — 793 Gain on sale of subsidiaries (152,208 ) — — (152,208 ) General and administrative 26,937 (370 ) — 26,567 Other charges 4,405 — — 4,405 Operating income 152,141 1,131 — 153,272 Non-operating income (expense) (36 ) 6 — (30 ) Pre-tax income 152,105 1,137 — 153,242 Provision for income taxes 57,210 — — 57,210 Income from discontinued operations $ 94,895 $ 1,137 $ — $ 96,032 Condensed Balance Sheets of the Discontinued Operations are as follows (in thousands): December 31, 2017 Professional Services Hawkeye Total Contract cost and recognized income not yet billed $ 324 $ — $ 324 Total assets associated with discontinued operations 324 — 324 Accounts payable and accrued liabilities 337 180 517 Other current liabilities 574 — 574 Other long-term liabilities 893 — 893 Total liabilities associated with discontinued operations 1,804 180 1,984 Net liabilities associated with discontinued operations $ (1,480 ) $ (180 ) $ (1,660 ) December 31, 2016 Professional Services Hawkeye Total Accounts receivable, net $ 313 $ — $ 313 Contract cost and recognized income not yet billed 192 — 192 Total assets associated with discontinued operations 505 — 505 Accounts payable and accrued liabilities 412 277 689 Contract billings in excess of costs 358 — 358 Other current liabilities 531 — 531 Other long-term liabilities 995 — 995 Total liabilities associated with discontinued operations 2,296 277 2,573 Net liabilities associated with discontinued operations $ (1,791 ) $ (277 ) $ (2,068 )

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment, which are used to secure debt or are subject to lien, at cost, as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Construction equipment $ 57,195 $ 59,607 Furniture and equipment 26,002 30,752 Land and buildings 1,715 1,521 Transportation equipment 57,346 65,501 Leasehold improvements 5,819 5,641 Marine equipment 82 82 Total property, plant and equipment 148,159 163,104 Less: accumulated depreciation (118,046 ) (124,981 ) Total property, plant and equipment, net $ 30,113 $ 38,123 Amounts above include $0.3 million and $0.8 million of construction in progress as of December 31, 2017 and 2016 , respectively. Depreciation expense included in operating expenses for the years ended December 31, 2017 , 2016 and 2015 was $9.5 million , $12.1 million and $17.3 million , respectively. In the fourth quarter of 2017, the Company performed an impairment assessment of all long-lived assets (including property, plant and equipment) associated with each of its asset groups under ASC 360. As a result of the Company’s assessment, no impairment to long-lived assets (including property, plant and equipment) was required. See Note 2 – Summary of Significant Accounting Policies for more information.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The Company’s intangible assets as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 Customer Relationships Trademark/ Tradename Total Balance as of December 31, 2016 $ 73,100 $ 3,748 $ 76,848 Amortization (8,597 ) (1,070 ) (9,667 ) Balance as of December 31, 2017 $ 64,503 $ 2,678 $ 67,181 Weighted average remaining amortization period 7.5 years 2.5 years December 31, 2016 Customer Relationships Trademark/ Tradename Total Balance as of December 31, 2015 $ 82,044 $ 4,818 $ 86,862 Amortization (8,684 ) (1,070 ) (9,754 ) Transfer to assets held for sale $ (260 ) $ — $ (260 ) Balance as of December 31, 2016 $ 73,100 $ 3,748 $ 76,848 Weighted average remaining amortization period 8.5 years 3.5 years In the fourth quarter of 2017, the Company performed an impairment assessment of all long-lived assets (including intangible assets) associated with each of its asset groups under ASC 360. As a result of the Company’s assessment, no impairment to long-lived assets (including intangible assets) was required. See Note 2 – Summary of Significant Accounting Policies for more information. Intangible assets are amortized on a straight-line basis over their estimated useful lives , which range from 5 to 15 years. Amortization expense was $9.7 million , $9.8 million and $9.9 million for the years ended December 31, 2017 , 2016 and 2015, respectively. Estimated amortization expense for each of the subsequent five years and thereafter is as follows (in thousands): Fiscal year: 2018 $ 9,667 2019 9,667 2020 9,135 2021 8,597 2022 8,597 Thereafter 21,518 Total amortization $ 67,181

Accounts Payable

Accounts Payable	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts Payable	Accounts Payable Accounts payable and accrued liabilities as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Trade accounts payable $ 54,414 $ 34,770 Payroll liabilities 12,185 10,377 Accrued contract costs 52,847 15,840 Self-insurance accrual 6,601 11,210 Other accrued liabilities 12,114 11,291 Total accounts payable and accrued liabilities $ 138,161 $ 83,488 Accrued contract costs includes $12.2 million and $3.7 million at December 31, 2017 and 2016 , respectively, related to provisions on loss projects. The self-insurance accrual includes $6.6 million and $11.2 million of short-term liabilities at December 31, 2017 and 2016 , respectively. The remaining $17.2 million and $14.5 million of the self-insurance accrual is included within “Other long-term liabilities” on the Consolidated Balance Sheets for the years ended December 31, 2017 and 2016 , respectively.

Debt Obligations

Debt Obligations	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations The Company’s debt obligations as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Aggregate outstanding principal balance, 2014 Term Loan Facility $ 107,224 $ 92,224 Repayment fee, 2014 Term Loan Facility 9,650 4,611 Unamortized discount – repayment fee, 2014 Term Loan Facility (7,235 ) (3,592 ) Unamortized debt issuance costs, 2014 Term Loan Facility (4,464 ) (4,054 ) Revolver borrowings, 2013 ABL Credit Facility 28,108 — Total debt obligations, net of unamortized discount and debt issuance costs $ 133,283 $ 89,189 Current maturities of long-term debt $ 105,175 $ — Short-term borrowings under revolving credit facility 28,108 — Long-term debt obligations — 89,189 Total debt obligations, net of unamortized discount and debt issuance costs $ 133,283 $ 89,189 2014 Term Loan Facility On December 15, 2014, the Company entered into a credit agreement (the “2014 Term Credit Agreement”) among the Company, certain of its subsidiaries, as guarantors, the lenders from time to time party thereto, and JPMorgan Chase Bank, N.A., as administrative agent. Cortland Capital Market Services LLC currently serves as administrative agent under the 2014 Term Credit Agreement. Principal, Interest and Maturity The 2014 Term Credit Agreement initially provided for a five -year $270.0 million term loan facility (the “2014 Term Loan Facility”), which the Company drew in full on the effective date of the 2014 Term Credit Agreement. Effective November 6, 2017, the Company amended the 2014 Term Credit Agreement pursuant to a Sixth Amendment (the “Sixth Amendment”). The Sixth Amendment, among other things, provides for an additional term loan in an amount equal to $15.0 million , which will be pari passu in right of payment with, and secured on a pari passu basis with the aggregate outstanding principal balance of the Company’s 2014 Term Loan Facility. The additional term loan was drawn in full on November 17, 2017 (the “Sixth Amendment Funding Date”) and bears the same maturity date as the aggregate outstanding principal balance of the Company’s 2014 Term Loan Facility. At December 31, 2017, the aggregate outstanding principal balance of the Company’s 2014 Term Loan Facility was approximately $107.2 million . The 2014 Term Loan Facility initially bore interest at the “Adjusted Base Rate” plus an applicable margin of 8.75 percent , or the “Eurodollar Rate” plus an applicable margin of 9.75 percent . The interest rate in effect at December 31, 2016 was 11 percent , which consisted of an applicable margin of 9.75 percent for Eurodollar Rate loans plus a LIBOR floor of 1.25 percent . On the Sixth Amendment Funding Date, the interest rate increased to 13 percent , consisting of an applicable margin of 11.75 percent for Eurodollar Rate loans plus a LIBOR floor of 1.25 percent . Beginning September 30, 2018 , the applicable margin will increase an additional 100 basis points each quarterly period until maturity. Subsequent to December 31, 2017, the Company amended the 2014 Term Credit Agreement pursuant to the Seventh Amendment. Under the terms of the Seventh Amendment, Primoris will provide the Company with an Initial First-Out Loan in an amount equal to $10.0 million to be drawn in full no earlier than three business days after the Seventh Amendment Effective Date. In addition, Primoris may provide the Company with Additional First-Out Loans up to $10.0 million . See Note 1 – Company Description and Financial Condition for more information. Makewhole Under the 2014 Term Credit Agreement, with respect to prepayments made from inception of the Term Loan through December 31, 2017 , the Company has not been required to pay prepayment premiums in respect of the “makewhole amount.” However, future prepayments or refinancing of the balance of the 2014 Term Loan Facility may require the Company to pay a prepayment premium equal to the makewhole amount and the repayment fee described below. Pursuant to the Sixth Amendment and beginning with the Sixth Amendment Funding Date, if a prepayment is made on or before September 30, 2018 , the makewhole amount will be calculated as the present value of all interest payments that would have been made on the amount prepaid from the date of the prepayment to June 15, 2019 at a rate per annum equal to the sum of the applicable margin on the date of the prepayment plus the greater of 1.25 percent and the Eurodollar rate in effect on the date of the repayment. If a prepayment is made after September 30, 2018 , the makewhole amount will be calculated as the present value of all interest payments that would have been made on the amount prepaid from the date of the prepayment to December 15, 2019 at a rate per annum equal to the sum of the applicable margin on the date of the prepayment plus the greater of 1.25 percent and the Eurodollar rate in effect on the date of the repayment. Should a prepayment in full occur under the Sixth Amendment, the estimated makewhole amount due at future prepayment dates would be as follows (in thousands): March 31, June 30, September 30, December 31, March 31, June 30, September 30, Makewhole $ 16,843 $ 13,358 $ 9,874 $ 16,888 $ 12,331 $ 7,595 $ 3,350 Repayment Fee Prior to the Sixth Amendment, the Company was also required to pay a repayment fee on the date of any prepayment and on the maturity date of the 2014 Term Loan Facility equal to a total of $4.6 million , which was 5.0 percent of the amount prepaid or 5.0 percent of the aggregate remaining outstanding principal balance on the maturity date. Pursuant to the Sixth Amendment and beginning with the Sixth Amendment Funding Date, the repayment fee increased to a total of $9.7 million , which is 9.0 percent of the amount prepaid or 9.0 percent of the aggregate remaining outstanding principal balance on the maturity date. The Company is amortizing the repayment fee as a discount, from that date through the maturity date of the 2014 Term Loan Facility, using the effective interest method. The unamortized amount of the repayment fee was $7.2 million at December 31, 2017 based on the 9.0 percent repayment fee in effect as of the Sixth Amendment Funding Date and $3.6 million at December 31, 2016 , based on the 5.0 percent repayment fee in effect as of that date. Term Loan Discounted Payoff The Seventh Amendment provides that the payment by the borrower of an amount equal to $100.0 million plus the expenses of the administrative agent in an amount not to exceed $1.1 million shall constitute payment in full and satisfaction and discharge of all obligations of the borrower and the other loan parties under the 2014 Term Credit Agreement, but solely if such payment is made in connection with the consummation of the merger. Accordingly, if the 2014 Term Loan Facility is paid off in connection with the closing of the merger, no amounts will be owed in respect of the makewhole amount and the repayment fee. See Note 1 – Company Description and Financial Condition for more information. Debt Covenants On March 31, 2015 (the “First Amendment Closing Date”), March 1, 2016, July 26, 2016 and March 3, 2017, the Company amended the 2014 Term Credit Agreement pursuant to a First Amendment (the “First Amendment”), a Third Amendment (the “Third Amendment”), a Fourth Amendment (the “Fourth Amendment”) and a Fifth Amendment (the “Fifth Amendment”). These amendments, among other things, suspended the calculation of the Maximum Total Leverage Ratio and Minimum Interest Coverage Ratio for the period from December 31, 2014 through June 30, 2017 (the “Covenant Suspension Periods”) so that any failure by the Company to comply with the Maximum Total Leverage Ratio or Minimum Interest Coverage Ratio during the Covenant Suspension Periods shall not be deemed to result in a default or event of default. In consideration of the initial suspension of the calculation of the Maximum Total Leverage Ratio and Minimum Interest Coverage Ratio under the First Amendment, the Company issued 10.1 million shares, which was equivalent to 19.9 percent of the then outstanding shares of common stock immediately prior to the First Amendment Closing Date, to KKR Lending Partners II L.P. and other entities indirectly advised by KKR Credit Advisers (US) LLC, which made them a related party. In connection with this transaction, the Company recorded debt covenant suspension charges of approximately $33.5 million which represented the fair value of the 10.1 million outstanding shares of common stock issued, multiplied by the closing stock price on the First Amendment Closing Date. In addition, the Company recorded debt extinguishment charges of approximately $0.8 million related to the write-off of debt issuance costs associated with the Company’s 2014 Term Credit Agreement. In consideration for the Third Amendment, Fourth Amendment and Fifth Amendment, the Company paid a total of $4.6 million in amendment fees during the year ended December 31, 2016 and $2.3 million in amendment fees during the year ended December 31, 2017 . The amendment fees are recorded as direct deductions from the carrying amount of the 2014 Term Loan Facility and are being amortized through the maturity date of the 2014 Term Loan Facility using the effective interest method. The Sixth Amendment suspends compliance with the Maximum Total Leverage Ratio and the Minimum Interest Coverage Ratio covenants through December 31, 2017. In addition, under the Sixth Amendment, the Maximum Total Leverage Ratio will be 5.50 to 1.00 as of March 31, 2018 and will decrease to 4.50 to 1.00 as of June 30, 2018, 4.25 to 1.00 as of September 30, 2018 and 3.00 to 1.00 as of March 31, 2019, and thereafter. The Minimum Interest Coverage Ratio will be 1.75 to 1.00 as of March 31, 2018, will increase to 2.00 to 1.00 as of June 30, 2018, decrease to 1.50 to 1.00 as of December 31, 2018 and increase to 2.75 to 1.00 as of March 31, 2019, and thereafter. The Sixth Amendment also provides that, for the four-quarter period ending March 31, 2018, Consolidated EBITDA shall be equal to the sum of Consolidated EBITDA for the quarterly periods ending December 31, 2017 and March 31, 2018 multiplied by two , and, for the four-quarter period ending June 30, 2018, Consolidated EBITDA shall be equal to the annualized sum of Consolidated EBITDA for the quarterly periods ending December 31, 2017, March 31, 2018 and June 30, 2018. Other The Company is the borrower under the 2014 Term Credit Agreement, with all of its obligations guaranteed by its material U.S. subsidiaries, other than excluded subsidiaries. Obligations under the 2014 Term Loan Facility are secured by a first priority security interest in, among other things, the borrower’s and the guarantors’ equipment, subsidiary capital stock and intellectual property (the “2014 Term Loan Priority Collateral”) and a second priority security interest in, among other things, the borrower’s and the guarantors’ inventory, accounts receivable, deposit accounts and similar assets. Unamortized debt issuance costs, primarily related to amendment fees associated with the 2014 Term Loan Facility, were $4.5 million and $4.1 million at December 31, 2017 and December 31, 2016 , respectively. These costs are being amortized through the maturity date of the 2014 Term Loan Facility using the effective interest method. The Company made no early payments during the year ended December 31, 2017 and $3.1 million of early payments during the year ended December 31, 2016 against the 2014 Term Loan Facility. As a result of these early payments, the Company recorded no debt extinguishment charges during the year ended December 31, 2017 and $0.1 million of debt extinguishment charges, which consisted of the write-off of debt issuance costs, during the year ended December 31, 2016 . 2013 ABL Credit Facility On August 7, 2013, the Company entered into a five -year asset based senior revolving credit facility maturing on August 7, 2018 with Bank of America, N.A. serving as sole administrative agent for the lenders thereunder, collateral agent, issuing bank and swingline lender (as amended, the “2013 ABL Credit Facility”). The aggregate amount of commitments for the 2013 ABL Credit Facility is $100.0 million , which is comprised of $90.0 million for the U.S. facility (the “U.S. Facility”) and $10.0 million for the Canadian facility (the “Canadian Facility”). At December 31, 2017, the Company had approximately $28.1 million in outstanding borrowings under the 2013 ABL Credit Facility for working capital purposes. The 2013 ABL Credit Facility includes a sublimit of $80.0 million for letters of credit. The borrowers under the U.S. Facility consist of all of the Company’s U.S. operating subsidiaries with assets included in the borrowing base, and the U.S. Facility is guaranteed by Willbros Group, Inc. and its material U.S. subsidiaries, other than excluded subsidiaries. The borrower under the Canadian Facility is Willbros Construction Services (Canada) LP, and the Canadian Facility is guaranteed by Willbros Group, Inc. and all of its material U.S. and Canadian subsidiaries, other than excluded subsidiaries. Advances under the U.S. and Canadian Facilities are limited to a borrowing base consisting of the sum of the following, less applicable reserves: • 85 percent of the value of “eligible accounts” (as defined in the 2013 ABL Credit Facility); • the lesser of (i) 75 percent of the value of “eligible unbilled accounts” (as defined in the 2013 ABL Credit Facility) and (ii) $33.0 million minus the amount of eligible unbilled accounts then included in the borrowing base; and • “eligible pledged cash”. The Company is also required, as part of its borrowing base calculation, to include a minimum of $25.0 million of the net proceeds of the sale of Bemis, LLC and the balance of the Professional Services segment as eligible pledged cash. The Company has included $40.0 million as eligible pledged cash in its December 31, 2017 borrowing base calculation, which is included in “Restricted cash” on its Consolidated Balance Sheets . The aggregate amount of the borrowing base attributable to eligible accounts and eligible unbilled accounts constituting certain progress or milestone billings, retainage and other performance-based benchmarks may not exceed $23.0 million . Advances in U.S. dollars bear interest at a rate equal to LIBOR or the U.S. or Canadian base rate plus an additional margin. Advances in Canadian dollars bear interest at the Bankers Acceptance (“BA”) Equivalent Rate or the Canadian prime rate plus an additional margin. The interest rate margins will be adjusted each quarter based on the Company’s fixed charge coverage ratio as of the end of the previous quarter as follows: Fixed Charge Coverage Ratio U.S. Base Rate, Canadian Base Rate and Canadian Prime Rate Loans LIBOR Loans, BA Rate Loans and Letter of Credit Fees >1.25 to 1 1.25% 2.25% ≤1.25 to 1 and >1.15 to 1 1.50% 2.50% ≤1.15 to 1 1.75% 2.75% The Company will also pay an unused line fee on each of the U.S. and Canadian Facilities equal to 50 basis points when usage under the applicable facility during the preceding calendar month is less than 50 percent of the commitments or 37.5 basis points when usage under the applicable facility equals or exceeds 50 percent of the commitments for such period. With respect to the letters of credit, the Company will pay a letter of credit fee equal to the applicable LIBOR margin, shown in the table above, on all letters of credit and a 0.125 percent fronting fee to the issuing bank, in each case, payable monthly in arrears. Obligations under the 2013 ABL Credit Facility are secured by a first priority security interest in the borrowers’ and guarantors’ accounts receivable, deposit accounts and similar assets (the “ABL Priority Collateral”) and a second priority security interest in the 2014 Term Loan Priority Collateral. On January 2, 2018, the Company paid down $2.5 million of its outstanding borrowings under the 2013 ABL Credit Facility using available cash on hand. If the Company’s unused availability under the 2013 ABL Credit Facility is less than the greater of (i) 15.0 percent of the revolving commitments or $15.0 million for five consecutive days, or (ii) 12.5 percent of the revolving commitments or $12.5 million at any time, or upon the occurrence of certain events of default under the 2013 ABL Credit Facility (“Cash Dominion”), the Company is subject to increased reporting requirements, the administrative agent shall have exclusive control over any deposit account, the Company will not have any right of access to, or withdrawal from, any deposit account, or any right to direct the disposition of funds in any deposit account, and amounts in any deposit account will be applied to reduce the outstanding amounts under the 2013 ABL Credit Facility. In addition, if the Company’s unused availability under the 2013 ABL Credit Facility is less than the amounts described above, the Company would be required to comply with a Minimum Fixed Charge Coverage Ratio of 1.15 to 1.00. In accordance with its December 31, 2017 borrowing base certificate completed in January 2018, the Company’s unused availability under the 2013 ABL Credit Facility was $12.8 million . As such, on January 30, 2018, in order to avoid Cash Dominion under the 2013 ABL Credit Facility, as described above, the Company paid down an additional $2.5 million of outstanding revolver borrowings under the 2013 ABL Credit Facility. The Company gives no assurance that it will continue to be able to avoid Cash Dominion under the 2013 ABL Credit Facility. If the Minimum Fixed Charge Coverage Ratio were to become applicable, the Company would not expect to be in compliance over the next twelve months and would therefore be in default under its credit agreements. Pursuant to the ABL Forbearance Agreement, the aggregate amount of commitments under the 2013 ABL Credit Facility has been reduced from $100.0 million to $90.0 million , which is comprised of $80.0 million for the U.S. Facility and $10.0 million for the Canadian Facility. In addition, during the ABL Forbearance Period, the Company may not request any additional loans or any new or increased letters of credit. The ABL Forbearance Agreement also provides that Cash Dominion will occur if the Company’s unused availability under the 2013 ABL Credit Facility is less than $10.0 million at any time. Events of Default A default under the 2014 Term Credit Agreement and the 2013 ABL Credit Facility may be triggered by events such as a failure to comply with financial covenants or other covenants under the 2014 Term Credit Agreement and the 2013 ABL Credit Facility, a failure to make payments when due under the 2014 Term Credit Agreement and the 2013 ABL Credit Facility, a failure to make payments when due in respect of, or a failure to perform obligations relating to, debt obligations in excess of $15.0 million , a change of control of the Company and certain insolvency proceedings. A default under the 2013 ABL Credit Facility would permit the lenders to terminate their commitment to make cash advances or issue letters of credit, require the immediate repayment of any outstanding cash advances with interest and require the cash collateralization of outstanding letter of credit obligations. A default under the 2014 Term Credit Agreement would permit the lenders to require immediate repayment of all principal, interest, fees and other amounts payable thereunder. The 2014 Term Credit Agreement and the 2013 ABL Credit Facility also include customary representations and warranties and affirmative and negative covenants, including: • the preparation of financial statements in accordance with GAAP; • the ability to deliver an audit opinion without a going concern explanation; • the identification of any events or circumstances, either individually or in the aggregate, that has had or could reasonably be expected to have a material adverse effect on the business, results of operations, properties or financial condition of the Company; • limitations on liens and indebtedness; • limitations on dividends and other payments in respect of capital stock; • limitations on capital expenditures; and • limitations on modifications of the documentation of the 2013 ABL Credit Facility. The Company’s inability to deliver audited financial statements without a going concern explanation constitutes an event of default under the 2014 Term Credit Agreement and the 2013 ABL Credit Facility. See Note 1 – Company Description and Financial Condition for more information. On March 27, 2018, the Company entered into a Term Forbearance Agreement with the Term Lenders and an ABL Forbearance Agreement with the ABL Lenders. If the merger with Primoris is not completed, or if these forbearance agreements were to expire or be terminated prior to the completion of the merger, the Term Lenders and ABL Lenders would be free to exercise any rights and remedies with respect to such defaults and events of defaults pursuant to the terms of the 2014 Term Credit Agreement and the 2013 ABL Credit Facility, respectively. See Note 1 – Company Description and Financial Condition for more information. Fair Value of Debt The estimated fair value of the Company’s debt instruments as of December 31, 2017 and December 31, 2016 was as follows (in thousands): December 31, 2017 December 31, 2016 2014 Term Loan Facility $ 119,042 $ 95,577 Revolver borrowings, 2013 ABL Credit Facility 28,108 — Total fair value of debt instruments $ 147,150 $ 95,577 The 2014 Term Loan Facility and revolver borrowings under the 2013 ABL Credit Facility are classified within Level 2 of the fair value hierarchy. The fair value of the 2014 Term Loan Facility has been estimated using discounted cash flow analyses based on the Company’s incremental borrowing rate for similar borrowing arrangements. The fair value of the revolver borrowings approximates its carrying value. Maturities The principal amounts due under the Company’s remaining debt obligations as of December 31, 2017 is as follows (in thousands): Fiscal year: 2018 $ 135,332 $ 135,332

Retirement Plans and Benefits

Retirement Plans and Benefits	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Plans and Benefits	Retirement Plans and Benefits The Company contributes to multiemployer defined benefit pension plans under the terms of collective-bargaining agreements that cover certain union-represented employees. Currently, the Company has no intention to withdraw from these plans. The risks of participating in a multiemployer plan are different from single-employer plans in the following aspects: a. Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. b. If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. c. If a participating employer chooses to stop participating in a multiemployer plan, the employer may be required to pay the plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. The Employee Retirement Income Security Act of 1974 (“ERISA”), as amended by the Multi-Employer Pension Plan Amendments Act of 1980, imposes certain liabilities upon employers who are contributors to a multiemployer plan in the event of the employer’s withdrawal from, or upon termination of, such plan. The plans do not maintain information on the net assets and actuarial present value of the plans’ unfunded vested benefits allocable to the Company. As such, the amount, if any, for which the Company may be contingently liable, is not ascertainable at this time. The majority of the Company’s unionized employees work in the building and construction industry (“B&C”), and, therefore, the Company believes it satisfies the criteria for the B&C industry exception under ERISA for those multiemployer pension plans that primarily cover employees in the B&C industry. As a result, the Company does not expect to be assessed a withdrawal liability when it ceases making contributions to those plans after the completion of a project or projects, so long as it does not continue to perform work in the jurisdiction of the pension plan on a non-union basis. The applicability of the B&C industry proviso is fact-specific, so there can be no assurance in any particular situation whether the B&C proviso applies or whether withdrawal liability will be assessed. The Pension Protection Act of 2006 added new funding rules generally applicable to plan years beginning after 2007 for multiemployer plans that are classified as “endangered,” “seriously endangered” or “critical” status. For a plan in endangered, seriously endangered or critical status, additional required contributions and benefit reductions may apply. A number of plans to which the Company’s business units contribute or may contribute in the future are in “endangered” or “critical” status. Certain of these plans may require additional contributions, generally in the form of a surcharge on future benefit contributions required for future work performed by union employees covered by these plans. The amount of additional funds, if any, that the Company may be obligated to contribute to these plans in the future cannot be estimated, as such amounts will likely be based on future levels of work that require the specific use of those union employees covered by these plans. The following table contains a summary of plan information relating to the Company’s participation in multiemployer pension plans, including Company contributions for the last three years, status of the multiemployer plan, and whether the plan is subject to a funding improvement, rehabilitation plan or contribution surcharges. Information has been presented separately for individually significant plans (defined as plans that make up 70 to 80 percent of the total Company defined benefit contributions and any plan that exceeds individual contributions of $0.1 million in any plan year presented). Fund EIN/PN PPA Plan Year Subject to 2017 2016 2015 Sur-charge Imposed Expiration Pennsylvania Heavy and Highway Contractors Pension Trust 23-6531755/ 001 Green 12/31/2016 No $ 2,085 $ 975 $ 1,086 No 12/31/2018 Boilermaker-Blacksmith National Pension Trust 48-6168020/ 001 Yellow 12/31/2016 Implemented $ — $ — $ 208 No N/A Other Funds — — 43 Total Contributions: $ 2,085 $ 975 $ 1,337 (1) The zone status is based on information that the Company received from the plan as well as publicly available information per the Department of Labor website and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than 65 percent funded, plans in the yellow zone are less than 80 percent funded, and plans in the green zone are at least 80 percent funded. Although the Boilermaker-Blacksmith National Pension Trust plan was considered to be in the yellow zone for 2016, it proactively entered critical status early for 2017 and imposed a surcharge for contributions payable after May 28, 2017. (2) The “Subject to Funding Improvement / Rehabilitation Plan” column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. The last column lists the expiration date(s) of the collective-bargaining agreement(s) to which the plans are subject. Based upon the most recent and available plan financial information, the Company made contributions to the Pennsylvania Heavy and Highway Contractors Pension Trust that represented more than 5 percent of total plan contributions for the 2016 plan year. In regards to the Boilermaker-Blacksmith National Pension Trust, the Company did not contribute to the plan in 2017 and has no collective bargaining agreements related to this plan. In addition to the contributions noted above to multiemployer defined benefit pension plans, the Company also makes discretionary contributions to defined contribution plans. The zone status outlined above does not apply to defined contribution plans. Contributions to all defined contribution and defined benefit plans were $9.1 million , $6.9 million and $9.9 million for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is domiciled in the United States and operates primarily in the United States and Canada. These countries have different tax regimes and tax rates, which affect the consolidated income tax provision of the Company and its effective tax rate. Moreover, losses from one country generally cannot be used to offset taxable income from another country, and some expenses incurred in certain tax jurisdictions receive no tax benefit, thereby affecting the effective tax rate. Tax Cuts and Jobs Act of 2017 On December 22, 2017, the President of the United States signed into law what is informally referred to as the Tax Cuts and Jobs Act of 2017 (the “Tax Act”), a comprehensive U.S. tax reform package that, effective January 1, 2018, among other things, lowered the corporate income tax rate from 35 percent to 21 percent and moved the country towards a territorial tax system with a one-time mandatory tax on previously deferred foreign earnings of foreign subsidiaries. Under the accounting rules, companies are required to recognize the effects of changes in tax laws and tax rates on deferred tax assets and liabilities in the period in which the new legislation is enacted. At December 31, 2017 , the Company has recognized the tax effects of the Tax Act as written and recorded a $0.7 million tax benefit. Below is a brief description of the effects from U.S. tax reform and its impact on the Company. Remeasurement of Deferred Taxes Under the Tax Act, the U.S. corporate income tax rate was reduced from 35 percent to 21 percent . As a result, the Company remeasured its U.S. deferred taxes as of December 31, 2017 . The remeasurement had no impact on tax expense or the Company’s effective tax rate due to the full valuation allowance. The valuation allowance decreased by $36.6 million . In addition, due to the remeasurement of the net operating loss (“NOL”), the ASC 740-10 reserve was remeasured at 21 percent , which resulted in a decrease to deferred taxes of $1.3 million with an offset to the valuation allowance. Reassessment of the Realizability of Deferred Tax Assets Under the Tax Act, the Alternative Minimum Tax Credit utilization rule was changed, which required the Company to reassess the realizability of the deferred tax asset. As a result, the Company has released the valuation allowance on the Refundable Alternative Minimum Tax Credit Carryforward and reclassified the asset from a deferred tax asset to a non-current receivable resulting in $0.7 million of tax benefit. The reclassification had a minimal impact on the Company’s effective tax rate. Liability for Taxes Due on Mandatory Deemed Repatriation Under the Tax Act, a company’s foreign earnings accumulated under the legacy tax laws are deemed to be repatriated into the United States. Since the Company discontinued its strategy of reinvesting foreign earnings in foreign operations in 2011, there is no impact to the tax provision as a result of the deemed repatriation. Upon completion of our 2017 U.S. income tax return in 2018, we may identify additional remeasurement adjustments to our recorded deferred tax assets. We will continue to assess our provision for income taxes as future guidance on the accounting effects of the Tax Act is issued but do not anticipate significant revisions will be necessary. Any such revisions will be recorded in the period in which they are identified, in accordance with the measurement period guidance outlined in SEC Staff Accounting Bulletin No. 118. Components of the Provision (Benefit) for Income Taxes Income (loss) before income taxes on continuing operations consists of the following (in thousands): Year Ended December 31, 2017 2016 2015 Foreign $ (4,406 ) $ (556 ) $ 334 United States (103,217 ) (43,756 ) (118,914 ) $ (107,623 ) $ (44,312 ) $ (118,580 ) Provision (benefit) for income taxes on continuing operations by country consists of the following (in thousands): Year Ended December 31, 2017 2016 2015 Current provision (benefit): Foreign $ (157 ) $ (550 ) $ 1,822 United States: Federal (833 ) 735 (51,475 ) State (391 ) (159 ) (4,497 ) (1,381 ) 26 (54,150 ) Deferred tax provision (benefit): Foreign 417 (556 ) 357 United States — — (238 ) 417 (556 ) 119 Total benefit for income taxes $ (964 ) $ (530 ) $ (54,031 ) The provision (benefit) for income taxes has been determined based upon the tax laws and rates in the countries in which operations are conducted and income is earned. The Company and its subsidiaries operating in the United States are subject to federal income tax rates up to 35 percent and varying state income tax rates and methods of computing tax liabilities. The Company’s principal international continuing operations are in Canada. The Company’s subsidiaries in Canada are subject to a corporate income tax rate of 27 percent . The Company did not have any non-taxable foreign earnings from tax holidays for taxable years 2015 through 2017 . In April 2011, the Company discontinued its strategy of reinvesting foreign earnings in foreign operations. The Company’s current operating strategy is not to reinvest all earnings of its operations internationally. Instead, dividends are distributed to the U.S. parent or its U.S. affiliates. Due to the current deficit in foreign earnings and profits, the Company does not anticipate a significant tax expense to future repatriations of foreign earnings in the United States. A reconciliation of the differences between the provision (benefit) for income taxes computed at the appropriate statutory rates and the reported provision (benefit) for income taxes is as follows (in thousands). For 2017 , 2016 and 2015 , the Company was domiciled in the United States, which has a 35 percent statutory tax rate. 2017 2016 2015 Taxes on earnings at statutory rate in domicile of parent company $ (37,668 ) $ (15,509 ) $ (41,503 ) Earnings taxed at rates less or greater than parent company rates: Foreign 443 246 (297 ) State income taxes, net of U.S. federal benefit — 116 (3,050 ) Non deductibles 3,033 2,017 2,681 Changes in provision for unrecognized tax positions 574 204 91 Change in valuation allowance 33,656 12,951 (19,027 ) Stock-based compensation 597 1,522 1,990 Deferred tax adjustments (276 ) (1,123 ) (595 ) Deemed dividend/previously taxed income — — 1,850 Prior year tax settlement 327 382 (246 ) Transfer pricing allocation (874 ) 6 2,011 Stock issuance costs — — 1,947 Alternative Minimum Tax credit carryforward — (1,031 ) — Other (124 ) (311 ) 117 Tax Cuts and Jobs Act (652 ) — — Total benefit for income taxes $ (964 ) $ (530 ) $ (54,031 ) For the year ended December 31, 2017 , the Company’s provision for income taxes for discontinued operations is $0.0 million , and the Company’s benefit for income taxes for continuing operations is $1.0 million for a net benefit for income taxes of $1.0 million on a consolidated basis. For the year ended December 31, 2016 , the Company’s provision for income taxes for discontinued operations was $0.1 million , and the Company’s benefit for income taxes for continuing operations was $0.5 million for a net benefit for income taxes of $0.4 million on a consolidated basis. For the year ended December 31, 2015 , the Company’s provision for income taxes for discontinued operations was $57.2 million , and the Company’s benefit for income taxes for continuing operations was $54.0 million for a net provision for income taxes of $3.2 million on a consolidated basis. As a result of the Tax Act, the NOL was remeasured from 35 percent to 21 percent . Due to the remeasurement of the NOL, the U.S. portion of the ASC 740-10 reserve was also remeasured at 21 percent , which decreased the gross position by $0.9 million with a full offset to the valuation allowance. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2017 2016 Beginning balance $ 2,406 $ 2,406 Impact of Tax Cuts and Jobs Act (870 ) — Other (49 ) — Ending balance $ 1,487 $ 2,406 At December 31, 2017 , there are no unrecognized tax benefits that will impact the Company’s effective tax rate if ultimately recognized. Due to the Tax Act, the Company remeasured interest and penalties on its U.S. positions from 35 percent to 21 percent , which resulted in a $0.4 million decrease to the reserve with a full offset to the valuation allowance. The Company has determined that, during the next twelve months, it is reasonably possible there will be no change in unrecognized tax benefits to be recognized due to the lapse of statutes of limitation in certain jurisdictions or settlement of audits. The Company recognizes interest and penalties accrued related to unrecognized tax benefits in income tax expense. During the years ended December 31, 2017 , 2016 and 2015 , the Company has recognized $0.2 million , $0.2 million and $0.2 million , respectively, in interest and penalties expense. The cumulative accrual for interest and penalties carried on the Consolidated Balance Sheets as of December 31, 2017 and 2016 is $1.0 million and $1.2 million , respectively. The Company files income tax returns in the United States federal jurisdiction, in various states and in various foreign jurisdictions. The Company is subject to examination for 2008 forward for the United States and the majority of the state jurisdictions and for 2010 forward in Canada. The principal components of the Company’s net deferred tax assets (liabilities) are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Non-current: Accrued vacation 293 144 Allowance for doubtful accounts 319 249 Estimated losses 2,021 143 Deferred compensation 311 696 Accrued insurance 4,620 7,581 Deferred rent 790 1,815 Various accrued liabilities 163 274 Goodwill 12,885 25,739 U.S. tax net operating loss carry forwards 53,617 59,258 State tax net operating loss carry forwards 8,201 6,148 Foreign tax net operating loss carry forwards 2,817 2,817 Alternative Minimum Tax credit carryforward — 846 Other 211 117 Gross deferred tax assets 86,248 105,827 Valuation allowance (68,003 ) (69,304 ) Deferred tax assets, net of valuation allowance 18,245 36,523 Deferred tax liabilities: Non-current: Term Loan amortization (394 ) (1,203 ) Depreciation (3,150 ) (7,409 ) Intangible amortization (14,701 ) (27,596 ) Deferred tax liabilities (18,245 ) (36,208 ) Net deferred tax assets $ — $ 315 United States $ — $ — Foreign — 315 Net deferred tax assets $ — $ 315 The valuation allowance for deferred income tax assets at December 31, 2017 and 2016 was $68.0 million and $69.3 million , respectively. Due to the Tax Act, $36.6 million of the valuation allowance was released which resulted in no impact to the Consolidated Statements of Operations . Valuation allowances exist in the U.S., Canada and Australia. The valuation allowances at December 31, 2017 are $64.7 million , $0.5 million and $2.8 million , respectively. The valuation allowances at December 31, 2016 are $66.5 million , $0.0 million and $2.8 million , respectively. At December 31, 2017 , the Company has remaining U.S. federal net operating loss carry forwards of $53.6 million and state net operating loss carry forwards of $8.2 million . The Company has a net operating loss carry forward for Australia of $2.8 million . The Company’s U.S. federal net operating losses expire beginning in 2031. The Company’s state net operating losses generally expire 20 years after the period in which the net operating loss was incurred. After the effect of tax planning strategies, carrybacks of certain federal net operating losses, reversals of existing temporary differences, and projections for future taxable income over the periods in which the deferred tax assets can be utilized to offset taxable income, the Company does not believe that the remaining net federal deferred tax asset is more likely than not realizable in the foreseeable future.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Changes in Accumulated Other Comprehensive Income (Loss) by Component Year Ended December 31, 2017 Foreign currency Changes in Total Balance, December 31, 2016 $ (1,412 ) $ (2,822 ) $ (4,234 ) Other comprehensive income before reclassifications 1,287 — 1,287 Amounts reclassified from accumulated other comprehensive income (loss) — 1,085 1,085 Net current-period other comprehensive income 1,287 1,085 2,372 Balance, December 31, 2017 $ (125 ) $ (1,737 ) $ (1,862 ) Year Ended December 31, 2016 Foreign currency Changes in Total Balance, December 31, 2015 $ (1,965 ) $ (4,044 ) $ (6,009 ) Other comprehensive income before reclassifications 553 — 553 Amounts reclassified from accumulated other comprehensive income (loss) — 1,222 1,222 Net current-period other comprehensive income 553 1,222 1,775 Balance, December 31, 2016 $ (1,412 ) $ (2,822 ) $ (4,234 ) Year Ended December 31, 2015 Foreign currency Changes in Total Balance, December 31, 2014 $ 6,863 $ (4,075 ) $ 2,788 Other comprehensive loss before reclassifications (8,828 ) (2,928 ) (11,756 ) Amounts reclassified from accumulated other comprehensive income (loss) — 2,959 2,959 Net current-period other comprehensive income (loss) (8,828 ) 31 (8,797 ) Balance, December 31, 2015 $ (1,965 ) $ (4,044 ) $ (6,009 ) Reclassifications out of Accumulated Other Comprehensive Income (Loss) Year Ended December 31, 2017 Details about Accumulated Other Comprehensive Income Components Amount Details about Accumulated Other Comprehensive Income Components Interest rate contracts $ 1,085 Interest expense, net Total $ 1,085 Year Ended December 31, 2016 Details about Accumulated Other Comprehensive Income Components Amount Details about Accumulated Other Comprehensive Income Components Interest rate contracts $ 1,222 Interest expense, net Total $ 1,222 Year Ended December 31, 2015 Details about Accumulated Other Comprehensive Income Components Amount Details about Accumulated Other Comprehensive Income Components Interest rate contracts $ 2,959 Interest expense, net Total $ 2,959 Stock Ownership Plans On June 1, 2017, the Company established the Willbros Group, Inc. 2017 Stock and Incentive Compensation Plan (the “2017 Plan”) to provide for awards to key employees of the Company. The 2017 Plan succeeds the 2006 Director Restricted Stock Plan (the “2006 Director Plan”) and the 2010 Stock and Incentive Compensation Plan (the “2010 Plan”). Beginning June 1, 2017, all future grants of stock awards to key employees will be made through the 2017 Plan, which had 4,960,315 shares available for grant at December 31, 2017 . Restricted Stock/Restricted Stock Units Restricted stock and restricted stock units or rights, also described collectively as restricted stock units (“RSUs”), granted to employees under the 2010 Plan and 2017 Plan generally vest over a 3 to 4 year period whereas RSUs granted under the 2006 Director Plan generally vest one year after the date of grant. The Company’s RSU activity and related information consist of: Year Ended December 31, 2017 Shares Weighted-Average Nonvested, beginning of year 1,219,446 $ 3.87 Granted 711,990 2.47 Vested (809,652 ) 4.10 Forfeited (108,137 ) 2.62 Nonvested, end of year 1,013,647 $ 2.84 For RSUs, certain provisions allow for accelerated vesting in the event of involuntary termination not for cause or a change of control of the Company. During the years ended December 31, 2017 , 2016 and 2015 , $0.4 million , $0.5 million and $2.3 million , respectively, of compensation expense was recognized due to accelerated vesting of RSUs due to retirements and separation from the Company. Stock-based compensation related to RSUs is recorded based on the Company’s closing stock price as of the grant date. The total fair value of RSUs vested during the years ended December 31, 2017 , 2016 and 2015 was $3.3 million , $5.9 million and $9.8 million , respectively. Performance Stock Units For performance stock units (“PSUs”) granted during the year ended December 31, 2017 , 2016 and 2015 , the number of shares that will vest is contingent upon the Company’s achievement of certain specified targets. These awards have market conditions and were valued using a Monte Carlo simulation model. The following table sets forth the assumptions used in the valuations of these awards: Year Ended December 31, 2017 2016 2015 Volatility 99.8% 91.1% 77.8% Risk-free interest rates 1.37% 1.01% 0.49% - 0.96% The volatility inputs were developed based on volatility observed using historical price observations over a look-back period consistent with the contractual terms of the awards. The risk-free interest rate inputs were derived using the US Treasury security rates as of the grant dates. Awards granted during the year ended December 31, 2015 included tranches with varying vesting periods, which resulted in the application of a range of risk-free rates. Stock Compensation Expense Expense related to all stock-based compensation arrangements totaled $2.9 million , $4.1 million and $8.6 million , respectively, for the years ended December 31, 2017 , 2016 and 2015 . As of December 31, 2017 , there was a total of $3.6 million of unrecognized compensation cost related to all non-vested stock-based compensation arrangements granted under the Company’s stock ownership plans. That cost is expected to be recognized over a weighted-average period of 2.30 years .

Income (Loss) Per Common Share

Income (Loss) Per Common Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Income (Loss) Per Common Share	Income (Loss) Per Common Share Basic income (loss) per share is computed by dividing net income (loss) by the weighted average number of common shares outstanding for the period. Diluted income (loss) per share is based on the weighted average number of shares outstanding during each period and the assumed exercise of potentially dilutive stock options and warrants and vesting of RSUs less the number of treasury shares assumed to be purchased from the proceeds using the average market price of the Company’s stock for each of the periods presented. Basic and diluted loss per common share is computed as follows (in thousands, except share and per share amounts): Year Ended December 31, 2017 2016 2015 Net loss from continuing operations applicable to common shares (numerator for basic and diluted calculation) $ (106,659 ) $ (43,782 ) $ (64,549 ) Weighted average number of common shares outstanding for basic loss per share 62,160,849 61,364,592 57,759,988 Weighted average number of potentially dilutive common shares outstanding — — — Weighted average number of common shares outstanding for diluted loss per share 62,160,849 61,364,592 57,759,988 Loss per common share from continuing operations: Basic $ (1.72 ) $ (0.71 ) $ (1.12 ) Diluted $ (1.72 ) $ (0.71 ) $ (1.12 ) The Company has excluded shares potentially issuable under the terms of use of the securities listed below from the number of potentially dilutive shares outstanding as the effect would be anti-dilutive: Year Ended December 31, 2017 2016 2015 Stock options — 32,787 55,000 Restricted stock and restricted stock rights 274,210 519,137 665,955 274,210 551,924 720,955

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information The Company has three reportable segments: Utility T&D, Canada and Oil & Gas . These segments are comprised of strategic businesses that are defined by the industries or geographic regions they serve. Each segment is led by a separate segment President who reports directly to the Company’s Chief Operating Decision Maker (“CODM”). The CODM evaluates segment performance using operating income which is defined as contract revenue less contract costs and segment overhead, such as amortization related to intangible assets and general and administrative expenses that are directly attributable to the segment. For additional information regarding the Company’s reportable segments, see Note 2 – Summary of Significant Accounting Policies for more information. On November 30, 2015, the Company sold the balance of its Professional Services segment to TRC. As such, the Professional Services segment, including the Company’s previously sold subsidiaries in 2015 of Downstream Professional Services, Premier and UtilX, are presented as discontinued operations in the tables below. For additional information, see Note 18 – Discontinued Operations for more information. The following tables reflect the Company’s operations for the years ended December 31, 2017 , 2016 and 2015 (in thousands) by its three reportable segments. Year Ended December 31, 2017 Utility T&D Canada Oil & Gas Corporate Eliminations Consolidated Contract revenue $ 506,978 $ 121,151 $ 221,939 $ — $ (85 ) $ 849,983 Contract costs 486,340 115,870 272,613 — (85 ) 874,738 Contract income (loss) 20,638 5,281 (50,674 ) — — (24,755 ) Amortization of intangibles 9,559 — 108 — — 9,667 General and administrative 16,360 7,659 9,584 21,090 — 54,693 Other charges — 1,667 139 420 — 2,226 Operating loss $ (5,281 ) $ (4,045 ) $ (60,505 ) $ (21,510 ) $ — (91,341 ) Non-operating expenses (16,282 ) Benefit for income taxes (964 ) Loss from continuing operations (106,659 ) Loss from discontinued operations, net of provision for income taxes (1,436 ) Net loss $ (108,095 ) Year Ended December 31, 2016 Utility T&D Canada Oil & Gas Corporate Eliminations Consolidated Contract revenue $ 418,387 $ 143,140 $ 170,448 $ — $ (290 ) $ 731,685 Contract costs 378,229 134,248 173,202 — (290 ) 685,389 Contract income (loss) 40,158 8,892 (2,754 ) — — 46,296 Amortization of intangibles 9,559 — 195 — — 9,754 General and administrative 15,035 8,538 12,175 25,245 — 60,993 Other charges (income) (3 ) 1,004 1,659 3,550 — 6,210 Operating income (loss) $ 15,567 $ (650 ) $ (16,783 ) $ (28,795 ) $ — (30,661 ) Non-operating expenses (13,651 ) Benefit for income taxes (530 ) Loss from continuing operations (43,782 ) Loss from discontinued operations, net of provision for income taxes (3,977 ) Net loss $ (47,759 ) Year Ended December 31, 2015 Utility T&D Canada Oil & Gas Corporate Eliminations Consolidated Contract revenue $ 379,629 $ 232,534 $ 297,110 $ — $ (279 ) $ 908,994 Contract costs 354,267 209,439 304,813 — (279 ) 868,240 Contract income (loss) 25,362 23,095 (7,703 ) — — 40,754 Amortization of intangibles 9,559 — 315 — — 9,874 General and administrative 9,841 12,245 20,154 35,095 — 77,335 Gain on sale of subsidiary — — — — — — (12,826 ) Other charges 2,002 624 9,852 5,991 — 18,469 Operating income (loss) $ 3,960 $ 10,226 $ (38,024 ) $ (41,086 ) $ — (52,098 ) Non-operating expenses (66,482 ) Benefit for income taxes (54,031 ) Loss from continuing operations (64,549 ) Income from discontinued operations, net of provision for income taxes 96,032 Net income $ 31,483 Depreciation and amortization expense by segment are presented below (in thousands): Year Ended December 31, 2017 2016 2015 Utility T&D $ 15,300 $ 16,511 $ 18,719 Canada 737 924 1,321 Oil & Gas 2,041 3,142 5,241 Corporate 1,084 1,342 1,919 Total $ 19,162 $ 21,919 $ 27,200 Capital expenditures by segment are presented below (in thousands): Year Ended December 31, 2017 2016 2015 Utility T&D $ 1,953 $ 2,493 $ 451 Canada 271 693 519 Oil & Gas 275 323 605 Corporate 62 293 608 Total $ 2,561 $ 3,802 $ 2,183 Total assets by segment as of December 31, 2017 and 2016 are presented below (in thousands): Year Ended December 31, 2017 2016 Utility T&D $ 196,923 $ 201,339 Canada 41,958 47,704 Oil & Gas 50,779 42,887 Corporate 73,893 70,601 Total assets, continuing operations $ 363,553 $ 362,531 Due to a limited number of major projects and clients, the Company may at any one time have a substantial part of its operations dedicated to one project, client and country. Customers representing 10 percent or more of total contract revenue are as follows: Year Ended December 31, 2017 2016 2015 Oncor 25.0 % 25.0 % 17.9 % Enterprise Products Partners L.P. 9.8 % 9.4 % 12.5 % On March 5, 2018, Oncor notified the Company of its election to extend its agreement with Willbros, under the terms and conditions currently in effect, through December 31, 2019. Information about the Company’s operations in its work countries is shown below (in thousands): Year Ended December 31, 2017 2016 2015 Contract revenue: United States $ 728,832 $ 588,545 $ 676,460 Canada 121,151 143,140 232,534 $ 849,983 $ 731,685 $ 908,994 Year Ended December 31, 2017 2016 Property, plant and equipment, net: United States $ 25,804 $ 33,625 Canada 4,309 4,498 $ 30,113 $ 38,123

Contingencies, Commitments and

Contingencies, Commitments and Other Circumstances	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingencies, Commitments and Other Circumstances	Contingencies, Commitments and Other Circumstances Contingencies Litigation and Regulatory Matters Related to the Company’s October 21, 2014 Press Release and December 4, 2014 8-K Announcing the Restatement of Condensed Consolidated Financial Statements for the Quarterly Periods Ended June 30, 2014 and March 31, 2014 After the Company announced it would be restating its Condensed Consolidated Financial Statements for the quarterly period ended June 30, 2014, a complaint was filed in the United States District Court for the Southern District of Texas (“USDC”) on October 28, 2014 seeking class action status on behalf of purchasers of the Company’s stock and alleging damages on their behalf arising from the matters that led to the restatement. The original defendants in the case were the Company, its former Chief Executive Officer, Robert R. Harl, and its former Chief Financial Officer, Van A. Welch. On January 30, 2015, the court named two employee retirement systems as Lead Plaintiffs. Lead Plaintiffs filed their consolidated complaint, captioned In re Willbros Group, Inc. Securities Litigation , on March 31, 2015, adding as a defendant John T. McNabb, II, the former Chief Executive Officer who had succeeded Mr. Harl, and claims regarding the restatement of the Company’s Condensed Consolidated Financial Statements for the quarterly period ended March 31, 2014. On June 15, 2015, Lead Plaintiffs filed a second amended consolidated complaint, seeking unspecified damages and asserting violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended (the “Act”), based on alleged misrepresentations and omissions in the SEC filings and other public disclosures in 2014, primarily regarding internal controls, the performance of the Oil & Gas segment, compliance with debt covenants and liquidity, certain financial results and the circumstances surrounding Mr. Harl’s departure. On July 27, 2015, the Company filed a motion to dismiss the case. At a hearing on May 24, 2016, the court granted the motion to dismiss in part and denied it in part. On July 22, 2016, the Company filed an answer to the suit denying the remaining allegations in the case, which complain of alleged misrepresentations and omissions in violation of the Act regarding internal controls, the performance of the Oil & Gas segment and Mr. Harl’s departure. On June 28, 2017, Lead Plaintiffs filed a motion asking the Court to reconsider its order in 2016 dismissing certain claims and allow Lead Plaintiffs to replead two of the claims the Court has dismissed; the Company opposes the motion. The Court heard oral argument but has not ruled. On February 16, 2018, the Company reached an agreement in principle, which, if approved by the Court, would settle all claims against the defendants and be funded by our insurance carriers. In addition, two shareholder derivative lawsuits were filed purportedly on behalf of the Company in connection with the restatement. The first, Markovich v. Harl et al , was filed on November 6, 2014 in the District Court of Harris County, Texas. The second, Kumararatne v. McNabb et al , was filed on March 4, 2015 in the USDC, but was voluntarily dismissed by the plaintiff on April 23, 2015. The Markovich lawsuit named certain former officers and current and former members of the Company’s Board of Directors as defendants and the Company as a nominal defendant. The lawsuit alleged that the officer and board member defendants breached their fiduciary duties by permitting the Company’s internal controls to be inadequate, failing to prevent the restatements, and wasting corporate assets, and that the defendants were unjustly enriched. The defendants sought dismissal of the lawsuit on the grounds that the plaintiff failed to make demand upon the Company’s board to bring the lawsuit, and, on February 23, 2016, the court sustained the defendants’ motion and dismissed the lawsuit with prejudice. On March 10, 2016, the plaintiff filed a motion for reconsideration and asked the court for leave to amend its lawsuit. The court granted the plaintiff’s motion in part, allowing an amended petition, which was filed on April 18, 2016. The Plaintiff’s Second Amended Petition added Ravi Kumararatne as a plaintiff and added claims for breach of fiduciary duty against the former officers and officer and Board of Director defendants related to the departure of former Company executives, financial controls, and compliance with the Company’s debt covenants. The Company sought dismissal of the amended petition on the grounds the plaintiffs failed to make a demand upon the Company’s board to bring the lawsuit. In response, plaintiffs filed a Third Amended Petition on June 24, 2016, purporting to add additional facts to support their allegations, including their allegation that they were excused from making a demand upon the board because, they claimed, such demand would be futile. Believing the claims added by plaintiffs were without merit, the Company sought to dismiss this latest pleading. After hearing argument on the motion, the court issued an order on October 24, 2016, sustaining the Company’s objections to plaintiffs’ latest pleading and again dismissed the lawsuit with prejudice. Plaintiffs’ motion for reconsideration was denied on December 21, 2016. Plaintiffs filed a Notice of Appeal on January 20, 2017. The appeal is assigned to the 14 th Court of Appeals, Houston, Texas; the court heard oral argument in the appeal on January 30, 2018 but has not yet issued an opinion. Other The SEC issued an order of investigation on January 29, 2015 and a subpoena on February 3, 2015, requesting information regarding the restatement of the Company’s previously issued Condensed Consolidated Financial Statements for the quarterly periods ended March 31, 2014 and June 30, 2014. The Company provided its full cooperation to the SEC, who on January 25, 2016, sent the Company a letter stating it had concluded its investigation and, based on the information it had, did not intend to recommend an enforcement action against the Company. In addition to the matters discussed above, the Company is party to a number of other legal proceedings. Management believes that the nature and number of these proceedings are typical for a firm of similar size engaged in a similar type of business and that none of these proceedings is material to the Company’s consolidated results of operations, financial position or cash flows. Commitments From time to time, the Company enters into commercial commitments, usually in the form of commercial and standby letters of credit, surety bonds and financial guarantees. Contracts with the Company’s customers may require the Company to secure letters of credit or surety bonds to secure the Company’s performance of contracted services. In such cases, the letters of credit or bond commitments can be called upon in the event of the Company’s failure to perform contracted services. Likewise, contracts may allow the Company to issue letters of credit or surety bonds in lieu of contract retention provisions, where the client otherwise withholds a percentage of the contract value until project completion or expiration of a warranty period. Retention letters of credit or bond commitments can be called upon in the event of warranty or project completion issues, as prescribed in the contracts. The Company also issues letters of credit from time to time to secure deductible obligations under its workers compensation, automobile and general liability policies. At December 31, 2017 , the Company had approximately $49.1 million of outstanding letters of credit. This amount represents the maximum amount of payments the Company could be required to make if these letters of credit are drawn upon. Additionally, the Company issues surety bonds (primarily performance in nature) that are customarily required by commercial terms on construction projects. At December 31, 2017 , these bonds outstanding had a face value at $155.3 million . This amount represents the bond penalty amount of future payments the Company could be required to make if the Company fails to perform its obligations under such contracts. The performance bonds do not have a stated expiration date; rather, each is released when the Company’s performance of the contract is accepted by the owner. The Company’s maximum exposure as it relates to the value of the bonds outstanding is lowered on each bonded project as the cost to complete is reduced. As of December 31, 2017 , no liability has been recognized for letters of credit or surety bonds. Operating Leases The Company has certain operating leases for various equipment and office facilities. Rental expense for continuing operations excluding daily rentals and reimbursable rentals under cost plus contracts was $16.3 million in 2017 , $23.3 million in 2016 , and $33.0 million in 2015 . Minimum lease commitments under operating leases as of December 31, 2017 , totaled $90.4 million and are payable as follows: 2018 , $25.1 million ; 2019 , $19.3 million ; 2020 , $14.1 million ; 2021 , $12.1 million ; 2022 , $6.9 million and thereafter, $12.9 million . Other Circumstances The Company has the usual liability of contractors for the completion of contracts and the warranty of its work. In addition, the Company acts as prime contractor on a majority of the projects it undertakes and is normally responsible for the performance of the entire project, including subcontract work. Management is not aware of any material exposure related thereto which has not been provided for in the accompanying Consolidated Financial Statements .

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The FASB’s standard on fair value measurements defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability, such as inherent risk, transfer restrictions, and risk of nonperformance. Fair Value Hierarchy The FASB’s standard on fair value measurements establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. This standard establishes 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. Level 3 – Unobservable inputs to the valuation methodology that are significant to the measurement of fair value of assets or liabilities. There were no transfers between levels in 2017 , 2016 or 2015 . The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable, notes payable, long-term debt and interest rate contracts. The fair value estimates of the Company’s financial instruments have been determined using available market information and appropriate valuation methodologies and approximate carrying value. Hedging Arrangements The Company is exposed to market risk associated with changes in non-U.S. currency exchange rates. To mitigate its risk, the Company may borrow Canadian dollars under its Canadian Facility to settle U.S. dollar account balances. The Company attempts to negotiate contracts that provide for payment in U.S. dollars, but it may be required to take all or a portion of payment under a contract in another currency. To mitigate non-U.S. currency exchange risk, the Company seeks to match anticipated non-U.S. currency revenue with expenses in the same currency whenever possible. To the extent it is unable to match non-U.S. currency revenue with expenses in the same currency, the Company may use forward contracts, options or other common hedging techniques in the same non-U.S. currencies. The Company had no forward contracts or options at December 31, 2017 and December 31, 2016 . The Company is subject to interest rate risk on its debt and investment of cash and cash equivalents arising in the normal course of business and had previously entered into hedging arrangements from time to time to fix or otherwise limit the interest cost of its variable interest rate borrowings. Termination of Interest Rate Swap Agreement In August 2013, the Company entered into an interest rate swap agreement (the “Swap Agreement”) for a notional amount of $124.1 million to hedge changes in the variable rate interest expense on $124.1 million of its existing or replacement LIBOR-indexed debt. The Swap Agreement was designated and qualified as a cash flow hedging instrument with the effective portion of the Swap Agreement’s change in fair value recorded in Other Comprehensive Income (“OCI”). The Swap Agreement was highly effective in offsetting changes in interest expense, and no hedge ineffectiveness was recorded in the Consolidated Statements of Operations . The Swap Agreement was terminated in the third quarter of 2015 for $5.7 million , which was recorded in OCI at fair value. In the fourth quarter of 2015, the Company made an early payment of $93.6 million against the 2014 Term Loan Facility and therefore reclassified approximately $1.2 million of the fair value of the Swap Agreement from OCI to interest expense. In the first quarter of 2016, the Company made an early payment of $3.1 million against the 2014 Term Loan Facility and therefore reclassified approximately $0.1 million of the fair value of the Swap Agreement from OCI to interest expense. The remaining fair value of the Swap Agreement included in OCI will be reclassified to interest expense over the remaining life of the underlying debt with approximately $1.1 million expected to be recognized in the coming twelve months. For the Year Ended December 31, Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Gain Recognized in OCI on Derivative (Effective Portion) Financial Statement Classification Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion) 2017 2016 2015 2017 2016 2015 Interest rate contracts $ — $ — $ (2,928 ) Interest expense, net $ 1,085 $ 1,222 $ 2,959 Total $ — $ — $ (2,928 ) $ 1,085 $ 1,222 $ 2,959

Other Charges

Other Charges	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Other charges	Other Charges The following table reflects the Company’s other charges for the years ended December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 Equipment and facility lease abandonment (1) $ (225 ) $ 3,633 $ 7,747 Loss on disposal of equipment (2) — 1,030 6,683 Employee severance charges 1,564 1,300 1,728 Restatement costs (3) 636 (24 ) 595 Impairment of intangible assets (4) — — 534 Accelerated stock vesting 251 271 1,182 Total $ 2,226 $ 6,210 $ 18,469 (1) Includes $0.0 million , $0.8 million and $1.8 million of costs associated with the write-off of deferred rent attributed to the abandonment of a portion of the Company’s corporate facility lease headquarters during the years ended December 31, 2017 , 2016 and 2015 , respectively. In addition, the 2017 amount includes a $0.8 million adjustment to decrease one of the Company’s lease abandonment liabilities. (2) 2016 loss is attributed to the fourth quarter disposal of $0.7 million in equipment associated with the abandonment of a portion of the Company’s corporate facility lease headquarters, as well as the $0.3 million loss on sale of the Oil & Gas segment’s fabrication business that was finalized during the year. 2015 loss is attributed to a $2.2 million loss on the sale of a corporate asset, impairment charges of $2.0 million in relation to the Oil & Gas segment’s fabrication services which was sold in 2016, impairment charges of $1.3 million in relation to construction equipment in the Utility T&D segment and the disposal of $1.2 million in equipment associated with the abandonment of a portion of the Company’s corporate facility lease headquarters. (3) Includes accounting and legal fees associated with the investigation of the root cause behind the deterioration of certain construction projects within the Oil & Gas segment, which led to the restatements of the Company’s Condensed Consolidated Financial Statements for the quarterly periods ended March 31, 2014 and June 30, 2014. (4) Attributed to intangible assets associated with fabrication, field and union construction turnaround services in the Oil & Gas segment. Activity in the accrual related to the equipment and facility lease abandonment charges during the year ended December 31, 2017 is as follows (in thousands): Utility T&D Canada Oil & Gas Corporate Total Accrued cost at December 31, 2016 $ 348 $ 290 $ 793 $ 4,048 $ 5,479 Cash payments (176 ) (120 ) (296 ) (1,127 ) (1,719 ) Non-cash charges (1) — — — 340 340 Change in estimates — 41 48 (314 ) (225 ) Accrued cost at December 31, 2017 $ 172 $ 211 $ 545 $ 2,947 $ 3,875 (1) Non-cash charges consist of accretion expense. The Company will continue to evaluate the need for additional equipment and facility lease abandonment charges, including the adequacy of its existing accrual, as conditions warrant.

Discontinued Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Assets Held for Sale Components of assets held for sale as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Accounts receivable, net $ 490 $ 7,806 Contract cost and recognized income not yet billed 234 136 Prepaid expenses and other assets 36 61 Parts and supplies inventories 409 468 Property, plant and equipment, net 375 318 Intangible assets, net 260 260 Other long-term assets — 1 Total assets held for sale 1,804 9,050 Accounts payable and accrued liabilities 100 3,789 Contract billings in excess of cost and recognized income 765 4,480 Other current liabilities — 3 Other long-term liabilities — 3 Total liabilities held for sale $ 865 $ 8,275 The Company, as part of its ongoing strategic evaluation, made the decision to offer the sale of its tank services business, which is included in the Company’s Oil & Gas segment, to an outside party. At December 31, 2017, the tank business was classified as held for sale, as it was being actively marketed, expected to sell within one year and measured at the lower of carrying value or fair value less costs to sell. On January 2, 2018, the Company sold its tank services business to ATS for $3.0 million , subject to working capital adjustments. Discontinued Operations The following disposals qualify for discontinued operations treatment with ASU 2014-08, which the Company adopted on January 1, 2015. Professional Services On November 30, 2015, the Company sold the balance of its Professional Services segment to TRC for $130.0 million in cash, subject to working capital and other adjustments. At closing, TRC held back $7.5 million from the purchase price (the “Holdback Amount”) until the Company effects the novation of a customer contract from one of the subsidiaries sold in the transaction to the Company (or obtains written approval of a subcontract of all the work that is the subject of such contract) and obtains certain consents. If such novation, subcontract or consents are not approved by March 15, 2016, TRC would pay the Holdback Amount to the Company. In connection with this transaction, the Company recorded a net gain on sale of $97.0 million during the year ended December 31, 2015. During the year ended December 31, 2016, the Company reached an agreement with TRC on substantially all of the outstanding items related to the sale of the Professional Services segment. As a result, the Company received $4.6 million during the year ended December 31, 2016 in relation to the sale and inclusive of the final settlement of working capital and the Holdback Amount and recorded $2.5 million in charges against the original net gain on sale in relation to working capital and other post-closing adjustments. Certain assets and liabilities associated with one Professional Services contract were retained by the Company and have been excluded from the transaction. In 2015, and prior to the sale of the balance of the Professional Services segment, the Company sold the following three subsidiaries that were historically part of the Professional Services segment. Downstream Professional Services On June 12, 2015, the Company sold all of its issued and outstanding equity of Downstream Professional Services to BR Engineers, LLC for approximately $10.0 million in cash. In connection with this transaction, the Company recorded a net loss on sale of $2.2 million during the year ended December 31, 2015. Premier On March 31, 2015, the Company sold all of its membership units in Premier to USIC Locating Services, LLC for approximately $51.0 million in cash, of which $4.0 million was deposited into an escrow account for a period of up to eighteen months to cover post-closing adjustments and any indemnification obligations of the Company. In connection with this transaction, the Company recorded a net gain on sale of $37.1 million during the year ended December 31, 2015. The Company received $3.7 million as full and final settlement of the outstanding escrow amount during the year ended December 31, 2016. UtilX On March 17, 2015, the Company sold all of its equity interests of UtilX to Novinium, Inc. for approximately $40.0 million in cash, of which $0.5 million was deposited into an escrow account for a period of six months to cover post-closing adjustments and any indemnification obligations of the Company. In the third quarter of 2015, the Company cleared the $0.5 million amount recorded in the escrow account as a post-closing adjustment. As a result of this transaction, the Company recorded a net gain on sale of $20.3 million during the year ended December 31, 2015. Hawkeye In the fourth quarter of 2013, the Company sold certain assets comprising its Hawkeye business to Elecnor Hawkeye, LLC, a subsidiary of Elecnor, Inc. Results of Discontinued Operations Condensed Statements of Operations of the Discontinued Operations for the years ended December 31, 2017 , 2016 and 2015 are as follows (in thousands): Year Ended December 31, 2017 Professional Services Hawkeye Other Total Contract revenue $ 1,006 $ — $ — $ 1,006 Contract costs 831 — — 831 General and administrative 1,219 (197 ) — 1,022 Other charges 525 — — 525 Operating income (loss) (1,569 ) 197 — (1,372 ) Non-operating income (expense) — — — — Pre-tax income (loss) (1,569 ) 197 — (1,372 ) Provision for income taxes 64 — — 64 Income (loss) from discontinued operations $ (1,633 ) $ 197 $ — $ (1,436 ) Year Ended December 31, 2016 Professional Services Hawkeye Other Total Contract revenue $ 2,126 $ — $ — $ 2,126 Contract costs 2,299 — — 2,299 Loss on sale of subsidiary 2,456 — — 2,456 General and administrative 2,633 (313 ) — 2,320 Other income (1,060 ) — — (1,060 ) Operating income (loss) (4,202 ) 313 — (3,889 ) Non-operating income (expense) — — — — Pre-tax income (loss) (4,202 ) 313 — (3,889 ) Provision for income taxes — — 88 88 Income (loss) from discontinued operations $ (4,202 ) $ 313 $ (88 ) $ (3,977 ) Year Ended December 31, 2015 Professional Services Hawkeye Other Total Contract revenue $ 229,482 $ 2,078 $ — $ 231,560 Contract costs 197,414 1,317 — 198,731 Amortization of intangibles 793 — — 793 Gain on sale of subsidiaries (152,208 ) — — (152,208 ) General and administrative 26,937 (370 ) — 26,567 Other charges 4,405 — — 4,405 Operating income 152,141 1,131 — 153,272 Non-operating income (expense) (36 ) 6 — (30 ) Pre-tax income 152,105 1,137 — 153,242 Provision for income taxes 57,210 — — 57,210 Income from discontinued operations $ 94,895 $ 1,137 $ — $ 96,032 Condensed Balance Sheets of the Discontinued Operations are as follows (in thousands): December 31, 2017 Professional Services Hawkeye Total Contract cost and recognized income not yet billed $ 324 $ — $ 324 Total assets associated with discontinued operations 324 — 324 Accounts payable and accrued liabilities 337 180 517 Other current liabilities 574 — 574 Other long-term liabilities 893 — 893 Total liabilities associated with discontinued operations 1,804 180 1,984 Net liabilities associated with discontinued operations $ (1,480 ) $ (180 ) $ (1,660 ) December 31, 2016 Professional Services Hawkeye Total Accounts receivable, net $ 313 $ — $ 313 Contract cost and recognized income not yet billed 192 — 192 Total assets associated with discontinued operations 505 — 505 Accounts payable and accrued liabilities 412 277 689 Contract billings in excess of costs 358 — 358 Other current liabilities 531 — 531 Other long-term liabilities 995 — 995 Total liabilities associated with discontinued operations 2,296 277 2,573 Net liabilities associated with discontinued operations $ (1,791 ) $ (277 ) $ (2,068 )

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) Selected unaudited quarterly financial data for the years ended December 31, 2017 and 2016 is presented below (in thousands): Year 2017 Quarter Ended March 31, 2017 June 30, 2017 September 30, 2017 December 31, 2017 Total 2017 Contract revenue $ 163,900 $ 227,447 $ 240,773 $ 217,863 $ 849,983 Contract income (loss) 1,681 17,079 (12,188 ) (31,327 ) (24,755 ) Operating income (loss) (14,853 ) 358 (27,789 ) (49,057 ) (91,341 ) Loss from continuing operations before income taxes (18,336 ) (3,318 ) (31,577 ) (54,392 ) (107,623 ) Loss from continuing operations (17,736 ) (1,121 ) (32,709 ) (55,093 ) (106,659 ) Income (loss) from discontinued operations, net of provision for income taxes (31 ) 19 (1,496 ) 72 (1,436 ) Net loss $ (17,767 ) $ (1,102 ) $ (34,205 ) $ (55,021 ) $ (108,095 ) Basic loss per share attributable to Company shareholders: Loss from continuing operations $ (0.29 ) $ (0.02 ) $ (0.52 ) $ (0.89 ) $ (1.72 ) Loss from discontinued operations — — (0.02 ) — (0.02 ) Net loss $ (0.29 ) $ (0.02 ) $ (0.54 ) $ (0.89 ) $ (1.74 ) Diluted loss per share attributable to Company shareholders: Loss from continuing operations $ (0.29 ) $ (0.02 ) $ (0.52 ) $ (0.89 ) $ (1.72 ) Loss from discontinued operations — — (0.02 ) — (0.02 ) Net loss $ (0.29 ) $ (0.02 ) $ (0.54 ) $ (0.89 ) $ (1.74 ) Weighted average number of common shares outstanding Basic 61,829,768 62,170,910 62,310,191 62,329,614 62,160,849 Diluted 61,829,768 62,170,910 62,310,191 62,329,614 62,160,849 Year 2016 Quarter Ended March 31, 2016 June 30, 2016 September 30, 2016 December 31, 2016 Total 2016 Contract revenue $ 199,030 $ 193,442 $ 174,821 $ 164,392 $ 731,685 Contract income 13,799 15,157 12,015 5,325 46,296 Operating loss (9,461 ) (2,741 ) (6,319 ) (12,140 ) (30,661 ) Loss from continuing operations before income taxes (13,131 ) (5,574 ) (9,869 ) (15,738 ) (44,312 ) Loss from continuing operations (13,298 ) (5,761 ) (10,661 ) (14,062 ) (43,782 ) Loss from discontinued operations, net of provision for income taxes (1,853 ) (658 ) (1,325 ) (141 ) (3,977 ) Net loss $ (15,151 ) $ (6,419 ) $ (11,986 ) $ (14,203 ) $ (47,759 ) Basic loss per share attributable to Company shareholders: Loss from continuing operations $ (0.22 ) $ (0.09 ) $ (0.17 ) $ (0.23 ) $ (0.71 ) Loss from discontinued operations (0.03 ) (0.01 ) (0.02 ) — (0.06 ) Net loss $ (0.25 ) $ (0.10 ) $ (0.19 ) $ (0.23 ) $ (0.77 ) Diluted loss per share attributable to Company shareholders: Loss from continuing operations $ (0.22 ) $ (0.09 ) $ (0.17 ) $ (0.23 ) $ (0.71 ) Loss from discontinued operations (0.03 ) (0.01 ) (0.02 ) — (0.06 ) Net loss $ (0.25 ) $ (0.10 ) $ (0.19 ) $ (0.23 ) $ (0.77 ) Weighted average number of common shares outstanding Basic 60,756,314 61,299,334 61,639,590 61,682,996 61,364,592 Diluted 60,756,314 61,299,334 61,639,590 61,682,996 61,364,592 Additional Notes: • During the quarter ended March 31, 2016, the Company made an early payment of $3.1 million against its Term Loan Facility and recorded debt extinguishment costs of $0.1 million , which consisted of the write-off of debt issuance costs. • During the quarter ended March 31, 2016, in relation to the sale of its Professional Services segment, the Company received $2.4 million of the Holdback Amount from TRC and recorded, as a working capital adjustment, a $1.5 million charge against the net gain on sale recorded during the quarter ended December 31, 2015. • During the quarter ended June 30, 2016, in relation to the sale of Premier, the Company received $2.0 million from USIC in relation to a portion of the outstanding escrow amount. • During the quarter ended June 30, 2016, in relation the sale of its Professional Services segment, the Company recorded, as a working capital adjustment, a $1.0 million charges against the net gain on sale recorded during the quarter ended December 31, 2015. • During the quarter ended September 30, 2016, in relation to the sale of its Professional Services segment, the Company received $2.2 million from TRC and inclusive of the final settlement of working capital and the Holdback Amount. • During the quarter ended September 30, 2016, in relation to the sale of Bemis, the Company received $0.9 million from Riggs Distler & Company in relation to a portion of the outstanding escrow amount. • During the quarter ended December 31, 2016, in relation to the sale of Premier, the Company received $1.7 million from USIC in relation to the full and final settlement of the outstanding escrow amount.

SCHEDULE II - CONSOLIDATED VALU

SCHEDULE II - CONSOLIDATED VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
SCHEDULE II - CONSOLIDATED VALUATION AND QUALIFYING ACCOUNTS	Year Ended Description Balance at Beginning of Year Charged (Credited) to Costs and Expense Charge Offs and Other Balance at End of Year December 31, 2015 Allowance for Bad Debts $ 2,723 $ 2,945 $ (1,186 ) $ 4,482 December 31, 2015 Deferred Tax Valuation Allowance 80,794 (22,359 ) — 58,435 December 31, 2016 Allowance for Bad Debts $ 4,482 $ 284 $ (2,803 ) $ 1,963 December 31, 2016 Deferred Tax Valuation Allowance 58,435 10,869 — 69,304 December 31, 2017 Allowance for Bad Debts $ 1,963 $ 887 $ (54 ) $ 2,796 December 31, 2017 Deferred Tax Valuation Allowance 69,304 (1,301 ) — 68,003

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Company	Company Description – Willbros Group, Inc., a Delaware corporation, and its subsidiaries (the “Company,” “Willbros” or “WGI”), is a specialty energy infrastructure contractor serving the oil and gas and power industries with offerings that primarily include construction, maintenance and facilities development services. The Company’s principal markets for continuing operations are the United States and Canada. The Company obtains its work through competitive bidding and negotiations with prospective clients. Contract values range from several thousand dollars to several hundred million dollars, and contract durations range from a few weeks to more than two years.
Segment Reporting	Business Segments – The Company has three reportable segments: Utility T&D , Canada and Oil & Gas . The Company’s Utility T&D segment provides a wide range of services in electric and natural gas transmission and distribution, including comprehensive engineering, procurement, maintenance and construction, repair and restoration of utility infrastructure. These services include engineering, design, installation, maintenance, procurement and repair of electrical transmission, distribution, substation, wireless and gas distribution systems. The Company’s Utility T&D segment conducts projects ranging from small engineering and consulting projects to multi-million dollar turnkey distribution, substation and transmission line projects, including those required for renewable energy facilities. The Company’s Canada segment provides construction, maintenance and fabrication services, including integrity and supporting civil work, pipeline construction, general mechanical and facility construction, American Petroleum Institute (“API”) storage tanks, general and modular fabrication, along with electrical and instrumentation projects serving the Canadian energy and water industries. The Company’s Oil & Gas segment provides construction, maintenance and lifecycle extension services to the midstream markets. These services include facilities construction such as tank terminals, pump stations, flow stations, gas compressor stations and metering stations, as well as small-diameter midstream pipeline construction, integrity construction, system maintenance, tank services and mainline pipeline construction.
Discontinued Operations	Discontinued Operations – On November 30, 2015, the Company sold the balance of its Professional Services segment to TRC Companies (“TRC”). As such, the Professional Services segment, including Willbros Engineers, LLC and Willbros Heater Services, LLC (collectively “Downstream Professional Services”), Premier Utility Services, LLC (“Premier”) and UtilX Corporation (“UtilX”), which were sold earlier in 2015, are presented as discontinued operations in the Company’s Consolidated Financial Statements . These subsidiaries, coupled with assets comprising the Company’s Hawkeye business that was sold in 2013 (“Hawkeye”), are referred to as the “Discontinued Operations.” Assets and liabilities related to the Discontinued Operations are included in the line item “Assets associated with discontinued operations,” “Current liabilities associated with discontinued operations” and “Long-term liabilities associated with discontinued operations” on the Consolidated Balance Sheets for all periods presented. The results of the Discontinued Operations are included in the line item “Income (loss) from discontinued operations, net of provision for income taxes” on the Consolidated Statements of Operations for all periods presented. See Note 18 – Discontinued Operations for more information.
Principles of Consolidation	Principles of Consolidation – The Consolidated Financial Statements of the Company include all of its majority-owned subsidiaries and all of its wholly-owned entities. Inter-company accounts and transactions are eliminated in consolidation. The ownership interest of noncontrolling participants in subsidiaries that are not wholly-owned is included as a separate component of equity.
Use of Estimates	Use of Estimates – The Consolidated Financial Statements are prepared in accordance with generally accepted accounting principles (“GAAP”) in the United States and include certain estimates and assumptions made by management of the Company in the preparation of the Consolidated Financial Statements . These estimates and assumptions relate to the reported amounts of assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenue and expense during the period. Significant items subject to such estimates and assumptions include revenue recognition under the percentage-of-completion method of accounting, including estimates of progress towards completion and estimates of gross profit or loss accrual on contracts in progress; tax accruals and certain other accrued liabilities; quantification of amounts recorded for contingencies; valuation allowances for accounts receivable and deferred income tax assets; and the carrying amount of property, plant and equipment, goodwill and intangible assets. The Company bases its estimates on historical experience and other assumptions that it believes relevant under the circumstances. Actual results could differ from these estimates.
Commitments and Contingencies	Commitments and Contingencies – Liabilities for loss contingencies arising from claims, assessments, litigation, fines, penalties and other sources are recorded when management assesses that it is probable that a liability has been incurred and the amount can be reasonably estimated. Recoveries of costs from third parties, which management assesses as being probable of realization, are recorded as “Other long-term assets” in the Consolidated Balance Sheets . Legal costs incurred in connection with matters relating to contingencies are expensed in the period incurred. See Note 15 – Contingencies, Commitments and Other Circumstances for more information.
Accounts Receivable	Accounts Receivable – Most of the accounts receivable and contract work in progress are from clients in the oil, gas, refinery, petrochemical and power industries in North America. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. Most contracts require payments as the projects progress or, in certain cases, advance payments. The Company generally does not require collateral, but in most cases can place liens against the property, plant or equipment constructed or terminate the contract if a material default occurs. The allowance for doubtful accounts is the Company’s best estimate of the probable amount of credit losses in the Company’s existing accounts receivable. A considerable amount of judgment is required in assessing the realization of receivables. Relevant assessment factors include the creditworthiness of the customer and prior collection history. Balances over 90 days past due are reviewed individually for collectability. Account balances are charged off against the allowance after all reasonable means of collection are exhausted and the potential for recovery is considered remote. The allowance requirements are based on the most current facts available and are re-evaluated and adjusted on a regular basis and as additional information is received.
Inventories	Inventories – Inventories, consisting primarily of parts and supplies, are stated at the lower of actual cost or market. Parts and supplies are evaluated at least annually and adjusted for excess and obsolescence.
Intangible Assets	Intangible Assets – The Company’s intangible assets with finite lives include customer relationships and trade names. The value of customer relationships is estimated using the income approach, specifically the excess earnings method. The excess earnings method consists of discounting to present value the projected cash flows attributable to the customer relationships, with consideration given to customer contract renewals, the importance or lack thereof of existing customer relationships to the Company’s business plan, income taxes and required rates of return. The value of trade names is estimated using the relief-from-royalty method of the income approach. This approach is based on the assumption that in lieu of ownership, a company would be willing to pay a royalty in order to exploit the related benefits of this intangible asset. The Company amortizes intangible assets based upon the estimated consumption of the economic benefits of each intangible asset or on a straight-line basis if the pattern of economic benefits consumption cannot otherwise be reliably estimated. Intangible assets subject to amortization are reviewed for impairment and are tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. For instance, a significant change in business climate or a loss of a significant customer, among other things, may trigger the need for an impairment test of intangible assets. An impairment loss is recognized if the carrying amount of an intangible asset is not recoverable and its carrying amount exceeds its fair value.
Property, Plant and Equipment	Property, Plant and Equipment – Property, plant and equipment is stated at cost. Depreciation, including amortization of capital leases, is provided on the straight-line method using estimated lives as follows: Construction equipment 3-20 years Furniture and equipment 3-12 years Buildings 20 years Transportation equipment 3-17 years Marine equipment 10 years Leasehold improvements are amortized on a straight-line basis over the shorter of their economic lives or the lease term. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized within operating expenses in the Consolidated Statements of Operations for the period. Normal repair and maintenance costs are charged to expense as incurred. Significant renewals and betterments are capitalized. The Company depreciates assets based on their estimated useful lives at the time of acquisition using the straight-line method. Depreciation and amortization related to operating activities is included in “Contract costs,” and depreciation and amortization related to general and administrative activities is included in “General and administrative” expense in the Consolidated Statements of Operations . “Contract costs” and “General and administrative” expenses are included within operating expenses in the Consolidated Statements of Operations . Further, amortization of assets under capital lease obligations is included in depreciation expense. Long-lived assets are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If an evaluation is required, the estimated future undiscounted cash flows associated with the asset are compared to the asset’s carrying amount to determine if an impairment of such asset is necessary. This evaluation, as well as an evaluation of our intangible assets, requires the Company to make long-term forecasts of the future revenues and costs related to the assets subject to review. Forecasts require assumptions about demand for the Company’s services and future market conditions. Estimating future cash flows requires significant judgment, and the Company’s projections may vary from the cash flows eventually realized. Future events and unanticipated changes to assumptions could require a provision for impairment in a future period. The effect of any impairment would be to expense the difference between the fair value (less selling costs) of such asset and its carrying value. Such expense would be reflected in earnings.
Revenue	Revenue – A number of factors relating to the Company’s business affect the recognition of contract revenue. The Company typically structures contracts as unit-price, time and materials, fixed-price or cost plus fixed fee. The Company believes that its operating results should be evaluated over a time horizon during which major contracts in progress are completed and change orders, extra work, variations in the scope of work, cost recoveries and other claims are negotiated and realized. Revenue from unit-price and time and materials contracts is recognized as earned. Revenue for fixed-price and cost plus fixed fee contracts is recognized using the percentage-of-completion method. Under this method, estimated contract income and resulting revenue is generally accrued based on costs incurred to date as a percentage of total estimated costs, taking into consideration physical completion. Total estimated costs, and thus contract income, are impacted by changes in productivity, scheduling, unit cost of labor, subcontracts, materials and equipment. Additionally, external factors such as weather, client needs, client delays in providing permits and approvals, labor availability, governmental regulation and politics may affect the progress of a project’s completion and thus the estimated amount and timing of revenue recognition. Certain fixed-price and cost plus fixed fee contracts include, or are amended to include, incentive bonus amounts, contingent on accomplishing a stated milestone. Revenue attributable to incentive bonus amounts is recognized when the risk and uncertainty surrounding the achievement of the milestone have been removed. The Company does not recognize income on a fixed-price contract until the contract is approximately five to ten percent complete, depending upon the nature of the contract. If a current estimate of total contract cost indicates a loss on a contract, the projected loss is recognized in full when determined. The Company considers unapproved change orders to be contract variations on which the Company has customer approval for scope change, but not for price associated with that scope change. Costs associated with unapproved change orders are included in the estimated cost to complete the contracts and are expensed as incurred. The Company recognizes revenue equal to cost incurred on unapproved change orders when realization of price approval is probable and the amount is estimable. Revenue recognized on unapproved change orders is included in “Contract cost and recognized income not yet billed” on the Consolidated Balance Sheets . Revenue recognized on unapproved change orders is subject to adjustment in subsequent periods to reflect the changes in estimates or final agreements with customers. The Company considers claims to be amounts that the Company seeks or will seek to collect from customers or others for customer-caused changes in contract specifications or design, or other customer-related causes of unanticipated additional contract costs on which there is no agreement with customers on both scope and price changes. Revenue from claims is recognized when agreement is reached with customers as to the value of the claims, which in some instances may not occur until after completion of work under the contract. Costs associated with claims are included in the estimated costs to complete the contracts and are expensed when incurred.
Insurance	Insurance – The Company is insured for workers’ compensation, employer’s liability, auto liability and general liability claims, subject to a deductible of $1.0 million per occurrence. Additionally, the Company’s largest non-union employee-related health care benefit plan is subject to a deductible of $0.3 million per claimant per year. Losses are accrued based upon the Company’s estimates of the ultimate liability for claims incurred (including an estimate of claims incurred but not reported), with assistance from third-party actuaries. For these claims, to the extent insurance coverage is above the deductible amounts, the Company has recorded a receivable reflected in “Other long-term assets” in the Consolidated Balance Sheets . These insurance liabilities are difficult to assess and estimate due to unknown factors, including the severity of an injury, the determination of the Company’s liability in proportion to other parties and the number of incidents not reported. The accruals are based upon known facts and historical trends.
Income Taxes	Income Taxes – The Financial Accounting Standards Board (“FASB”) standard for income taxes takes into account the differences between financial statement treatment and tax treatment of certain transactions. Deferred tax assets and liabilities are recognized for the expected future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of a change in tax rates due to changes in legislation is recognized as income or expense in the period that includes the enactment date. The ultimate realization of deferred tax assets related to net operating loss carry forwards, including federal and state net operating loss carry forwards, is dependent upon the generation of future taxable income in a particular tax jurisdiction during the periods in which the use of such net operating losses are allowed. The Company considers future taxable income, including the impacts of reversing taxable temporary differences, future forecasted income and available tax planning strategies, when evaluating whether deferred tax assets are more likely than not to be realized prior to expiration. The Company files income tax returns in the United States federal jurisdiction, in various states and in various foreign jurisdictions. The Company is subject to examination for 2008 forward for the United States and the majority of the state jurisdictions and for 2010 forward in Canada.
Retirement Plans and Benefits	Retirement Plans and Benefits – The Company has a voluntary defined contribution retirement plan for U.S. based employees that is qualified and contributory on the part of the employees. Additionally, the Company is subject to collective bargaining agreements with various unions. As a result, the Company participates with other companies in the unions’ multi-employer pension and other postretirement benefit plans.
Stock-Based Compensation	Stock-Based Compensation – Compensation cost resulting from all share-based payment transactions is recognized in the financial statements measured based on the grant-date fair value of the instrument issued and is recognized over the vesting period. Share-based compensation related to restricted stock and restricted stock units or rights, also described collectively as restricted stock units, is recorded based on the Company’s closing stock price as of the grant date. Awards granted are expensed ratably over the vesting period of the award.
Foreign Currency Translation	Foreign Currency Translation – All significant monetary asset and liability accounts denominated in currencies other than United States dollars are translated into United States dollars at current exchange rates. Translation adjustments are included in “Other comprehensive income (loss), net of tax” in the Company’s Consolidated Statements of Comprehensive Income (Loss) . Revenue and expense accounts are converted at prevailing rates throughout the year. Gains or losses on foreign currency transactions are recorded in income in the period in which they are incurred.
Concentration of Credit Risk	Concentration of Credit Risk – The Company has a concentration of customers in the oil and gas and power industries which expose the Company to a concentration of credit risk within a single industry. The Company seeks to obtain advance and progress payments for contract work performed on major contracts. Receivables are generally not collateralized.
Income (Loss) per Common Share	Income (Loss) per Common Share – Basic income (loss) per share is calculated by dividing net income (loss), less any preferred dividend requirements, by the weighted-average number of common shares outstanding during the year. Diluted income (loss) per share is calculated by including the weighted average number of all potentially dilutive common shares with the weighted-average number of common shares outstanding.
Derivative Financial Instruments	Derivative Financial Instruments – The Company may use derivative financial instruments such as forward contracts, options or other common hedging techniques to mitigate non-U.S. currency exchange risk when the Company is unable to match non-U.S. currency revenue with expense in the same currency. The Company has no forward contracts or options at December 31, 2017 and 2016 . The Company is subject to interest rate risk on its debt and investment of cash and cash equivalents arising in the normal course of business and has previously entered into hedging arrangements from time to time to fix or otherwise limit the interest cost of the variable interest rate borrowings.
Cash Equivalents	Cash Equivalents – The Company considers all highly liquid investments with an original maturity of 3 months or less to be cash equivalents.
Short-term Investments	Short-term Investments – The Company may invest a portion of its cash in short-term time deposits, some of which may have early withdrawal penalties. All such deposits have maturity dates that exceed three months .
Recent Accounting Pronouncements	Accounting Pronouncements Recently Adopted – In March 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-09, which changes how companies account for certain aspects of share-based payment awards to employees, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2016 and interim periods within those annual periods with early adoption permitted. The Company adopted ASU 2016-09 in the first quarter with an effective date of January 1, 2017. The recognition of previously unrecognized windfall tax benefits increased the Company’s deferred tax assets by $1.8 million offset by a related valuation allowance which resulted in a $0 cumulative-effect adjustment, net of tax, on the Company’s Consolidated Balance Sheet as of the beginning of 2017. The amendments within ASU 2016-09 related to the recognition of excess tax benefits and tax shortfalls in the Consolidated Statement of Operations and presentation within the operating section of the Consolidated Statement of Cash Flows were adopted prospectively with no adjustments to prior periods. The Company has elected to account for forfeitures as they occur. The remaining provisions of ASU 2016-09 did not have a material effect on the Company’s Consolidated Financial Statements . Accounting Pronouncements Not Yet Adopted – Revenue Recognition – In May 2014, the FASB issued ASU 2014-09 governing the recognition of revenue from contracts with customers. Under the new standard, a company will recognize revenue when it satisfies a performance obligation by transferring a promised good or service to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods and services. The standard also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. In August 2015, under ASU 2015-14, the FASB deferred the effective date of the standard to December 15, 2017 with early adoption permitted. The standard can be applied on a full retrospective or modified retrospective basis whereby the entity records a cumulative effect of initially applying this update at the date of initial application. Furthermore, in March, April, and May of 2016, the FASB issued ASUs 2016-08, 2016-10, and 2016-12, respectively, which provide practical expedients and clarification in regards to ASU 2014-09. ASU 2016-08 amends and clarifies the principal versus agent considerations under the new revenue recognition standard, which requires determination of whether the nature of a promise is to provide the specified good or service to the customer (that is, the entity is a principal) or to arrange for the good or service to be provided to the customer by another party (that is, the entity is an agent). This determination affects the timing and amount of revenue recognition. ASU 2016-10 clarifies issues related to identifying performance obligations. ASU 2016-12 provides practical expedients and clarification pertaining to the exclusion of sales tax from the measurement of a transaction price, the measurement of noncash consideration, allocation of a transaction price on the basis of all satisfied and unsatisfied performance obligations in a modified contract at transition, and the definition of a completed contract. The effective date of ASUs 2016-08, 2016-10, and 2016-12 is December 15, 2017 with early adoption permitted. Quantitative Disclosures of Directional Effects of Adoption The Company will adopt the new revenue guidance effective January 1, 2018 via the modified retrospective approach, by recognizing the cumulative effect of initially applying the new standard as an increase to the opening balance of retained earnings. Although still under the process of determining the impact, we expect this adjustment to be an immaterial impact to our opening balance of retained earnings as well as net income and earnings per share on an ongoing basis. Qualitative Status of Management’s Implementation Efforts Upon our initial evaluation of ASU 2014-09, there are no material changes in the standard that impact our revenue recognition relating to the allocation and measurement of contract revenues and the timing in which those revenues are recognized. However, the new standard will require a substantial increase in the amount and complexity of disclosures related to revenue recognition. The Company has taken steps to effectively implement the new standard by evaluating a representative sample of contracts with customers to identify the potential impacts that would result from applying the requirements of the standard to the Company’s existing revenue contracts. For most of the contracts entered into, the Company expects there to be a similar number of performance obligations, and in most cases, the Company has determined that the method of revenue recognition for these contracts will remain the same with the Company already considering different elements, such as variable consideration, when evaluating their transaction prices. The Company continues analyzing stand-alone pricing of the obligations as well as the timing related to revenue recognition. Significant judgments were used when concluding on the method of revenue recognition, but, in most cases, the Company determined that over time revenue recognition was appropriate via the percentage-of-completion method, based on time incurred, or as units are produced in accordance with the three over time criteria within ASC 606-10-25-27. However, there were also various industry-specific elements that the Company has identified that will have to be continuously monitored as new contracts are entered into in associated with ASU 2014-09, including uninstalled materials, customer provided materials and other elements. The Company has started to update its current accounting policies to align with revenue recognition practices under the new standard. As part of its evaluation of contracts with customers, the Company is holding regular meetings with key stakeholders across the organization to determine the impacts of the standards on its business processes. Additionally, the Company is evaluating its processes to address risks associated with incorporating these standards, and upon adoption, the Company expects to implement new internal controls related to accounting policies and procedures in order to validate the processes implemented upon adoption and going forward. Various trainings of the Accounting team are also expected to be held to further educate the business when applying some of the significant judgments required as part of the new standard. The Company is continuing to evaluate the future impact and method of adoption of ASU 2014-09 and related amendments on its Consolidated Financial Statements and related disclosures. Accounting Pronouncements Not Yet Adopted – Other – In February 2018, the FASB issued ASU 2018-02, which provides that the stranded tax effects from the Tax Cuts and Jobs Act on the balance of other comprehensive earnings may be reclassified to retained earnings. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with an option to adopt early. We are evaluating the effect of the standard on our Consolidated Financial Statements . In May 2017, the FASB issued ASU 2017-09, which clarifies when a change to the terms or conditions of a share-based payment award should be accounted for as a modification. An entity should account for the effects of a modification unless the fair value, vesting conditions and classification, as an equity instrument or a liability instrument, of the modified award are the same before and after a change to the terms or conditions of the share-based payment award. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company does not expect the new standard to have a material impact on its Consolidated Financial Statements . In November 2016, the FASB issued ASU 2016-18, which requires a reporting entity to include restricted cash and restricted cash equivalents in its cash and cash-equivalent balances presented in the entity’s statement of cash flows. A reconciliation between the statement of financial position and the statement of cash flows must be disclosed when the balance sheet includes more than one line item for cash, cash equivalents, restricted cash and restricted cash equivalents. Transfers between non-restricted and restricted cash should not be presented as cash flow activities in the statement of cash flows. Furthermore, an entity with a material restricted cash balance must disclose information regarding the nature of the restrictions. The standard is effective for annual periods beginning after December 15, 2017, including interim periods within those annual reporting periods. At December 31, 2017 and December 31, 2016 , approximately $40.4 million and $40.2 million , respectively, is recorded as “Restricted cash” on the Company’s Consolidated Balance Sheets . These amounts are primarily composed of eligible pledged cash in the Company’s December 31, 2017 and December 31, 2016 borrowing base calculation. The Company will adopt this standard in the first quarter of 2018. In October 2016, the FASB issued ASU 2016-16, which requires a reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. The new guidance does not apply to intra-entity transfers of inventory, and the income tax consequences from the sale of inventory from one member of a consolidated entity to another will continue to be deferred until the inventory is sold to a third party. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company does not expect the new standard to have any impact on its Consolidated Financial Statements . In August 2016, the FASB issued ASU 2016-15, which provides specific guidance for cash flow classifications of cash payments and receipts to reduce the diversity of treatment of such items. The standard is effective for annual periods beginning after December 15, 2017 and interim periods within those annual periods with early adoption permitted. The Company does not expect the new standard to have a material impact on its Consolidated Financial Statements . In February 2016, the FASB issued ASU 2016-02, which requires companies that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those assets. The standard is effective for interim and annual periods beginning after December 15, 2018. Early adoption is permitted for financial statements of fiscal years or interim periods that have not been previously issued. The Company is currently evaluating the impact of the standard on its Consolidated Financial Statements . Based on initial evaluation, the Company expects to include operating leases with durations greater than twelve months on its Consolidated Balance Sheets . The Company will provide additional information about the expected financial impact as it progresses through the evaluation and implementation of the standard.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Property Plant and Equipment	Depreciation, including amortization of capital leases, is provided on the straight-line method using estimated lives as follows: Construction equipment 3-20 years Furniture and equipment 3-12 years Buildings 20 years Transportation equipment 3-17 years Marine equipment 10 years

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Accounts Receivable, Net	Accounts receivable, net as of December 31, 2017 and 2016 is comprised of the following (in thousands): December 31, 2017 2016 Trade $ 95,923 $ 79,348 Unbilled revenue 22,018 20,447 Contract retention 26,146 12,091 Other receivables 901 2,114 Total accounts receivable 144,988 114,000 Less: allowance for doubtful accounts (2,796 ) (1,963 ) Total accounts receivable, net $ 142,192 $ 112,037

Contracts in Progress (Tables)

Contracts in Progress (Tables)	12 Months Ended
	Dec. 31, 2017
Contractors [Abstract]
Schedule of Contract Cost and Recognized Income Not Yet Billed and Related Amounts	Contract cost and recognized income not yet billed and related amounts billed as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Cost incurred on contracts in progress $ 445,029 $ 234,544 Recognized income (14,536 ) 28,702 430,493 263,246 Progress billings and advance payments (434,315 ) (256,246 ) $ (3,822 ) $ 7,000 Contract cost and recognized income not yet billed $ 13,992 $ 11,938 Contract billings in excess of cost and recognized income (17,814 ) (4,938 ) $ (3,822 ) $ 7,000

Assets Held For Sale (Tables)

Assets Held For Sale (Tables)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Components of Assets Held for Sale	Components of assets held for sale as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Accounts receivable, net $ 490 $ 7,806 Contract cost and recognized income not yet billed 234 136 Prepaid expenses and other assets 36 61 Parts and supplies inventories 409 468 Property, plant and equipment, net 375 318 Intangible assets, net 260 260 Other long-term assets — 1 Total assets held for sale 1,804 9,050 Accounts payable and accrued liabilities 100 3,789 Contract billings in excess of cost and recognized income 765 4,480 Other current liabilities — 3 Other long-term liabilities — 3 Total liabilities held for sale $ 865 $ 8,275 Condensed Statements of Operations of the Discontinued Operations for the years ended December 31, 2017 , 2016 and 2015 are as follows (in thousands): Year Ended December 31, 2017 Professional Services Hawkeye Other Total Contract revenue $ 1,006 $ — $ — $ 1,006 Contract costs 831 — — 831 General and administrative 1,219 (197 ) — 1,022 Other charges 525 — — 525 Operating income (loss) (1,569 ) 197 — (1,372 ) Non-operating income (expense) — — — — Pre-tax income (loss) (1,569 ) 197 — (1,372 ) Provision for income taxes 64 — — 64 Income (loss) from discontinued operations $ (1,633 ) $ 197 $ — $ (1,436 ) Year Ended December 31, 2016 Professional Services Hawkeye Other Total Contract revenue $ 2,126 $ — $ — $ 2,126 Contract costs 2,299 — — 2,299 Loss on sale of subsidiary 2,456 — — 2,456 General and administrative 2,633 (313 ) — 2,320 Other income (1,060 ) — — (1,060 ) Operating income (loss) (4,202 ) 313 — (3,889 ) Non-operating income (expense) — — — — Pre-tax income (loss) (4,202 ) 313 — (3,889 ) Provision for income taxes — — 88 88 Income (loss) from discontinued operations $ (4,202 ) $ 313 $ (88 ) $ (3,977 ) Year Ended December 31, 2015 Professional Services Hawkeye Other Total Contract revenue $ 229,482 $ 2,078 $ — $ 231,560 Contract costs 197,414 1,317 — 198,731 Amortization of intangibles 793 — — 793 Gain on sale of subsidiaries (152,208 ) — — (152,208 ) General and administrative 26,937 (370 ) — 26,567 Other charges 4,405 — — 4,405 Operating income 152,141 1,131 — 153,272 Non-operating income (expense) (36 ) 6 — (30 ) Pre-tax income 152,105 1,137 — 153,242 Provision for income taxes 57,210 — — 57,210 Income from discontinued operations $ 94,895 $ 1,137 $ — $ 96,032 Condensed Balance Sheets of the Discontinued Operations are as follows (in thousands): December 31, 2017 Professional Services Hawkeye Total Contract cost and recognized income not yet billed $ 324 $ — $ 324 Total assets associated with discontinued operations 324 — 324 Accounts payable and accrued liabilities 337 180 517 Other current liabilities 574 — 574 Other long-term liabilities 893 — 893 Total liabilities associated with discontinued operations 1,804 180 1,984 Net liabilities associated with discontinued operations $ (1,480 ) $ (180 ) $ (1,660 ) December 31, 2016 Professional Services Hawkeye Total Accounts receivable, net $ 313 $ — $ 313 Contract cost and recognized income not yet billed 192 — 192 Total assets associated with discontinued operations 505 — 505 Accounts payable and accrued liabilities 412 277 689 Contract billings in excess of costs 358 — 358 Other current liabilities 531 — 531 Other long-term liabilities 995 — 995 Total liabilities associated with discontinued operations 2,296 277 2,573 Net liabilities associated with discontinued operations $ (1,791 ) $ (277 ) $ (2,068 )

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment, which are used to secure debt or are subject to lien, at cost, as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Construction equipment $ 57,195 $ 59,607 Furniture and equipment 26,002 30,752 Land and buildings 1,715 1,521 Transportation equipment 57,346 65,501 Leasehold improvements 5,819 5,641 Marine equipment 82 82 Total property, plant and equipment 148,159 163,104 Less: accumulated depreciation (118,046 ) (124,981 ) Total property, plant and equipment, net $ 30,113 $ 38,123

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in the Carrying Amounts of Intangible Assets	The Company’s intangible assets as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 Customer Relationships Trademark/ Tradename Total Balance as of December 31, 2016 $ 73,100 $ 3,748 $ 76,848 Amortization (8,597 ) (1,070 ) (9,667 ) Balance as of December 31, 2017 $ 64,503 $ 2,678 $ 67,181 Weighted average remaining amortization period 7.5 years 2.5 years December 31, 2016 Customer Relationships Trademark/ Tradename Total Balance as of December 31, 2015 $ 82,044 $ 4,818 $ 86,862 Amortization (8,684 ) (1,070 ) (9,754 ) Transfer to assets held for sale $ (260 ) $ — $ (260 ) Balance as of December 31, 2016 $ 73,100 $ 3,748 $ 76,848 Weighted average remaining amortization period 8.5 years 3.5 years
Estimated Amortization Expense	Estimated amortization expense for each of the subsequent five years and thereafter is as follows (in thousands): Fiscal year: 2018 $ 9,667 2019 9,667 2020 9,135 2021 8,597 2022 8,597 Thereafter 21,518 Total amortization $ 67,181

Accounts Payable (Tables)

Accounts Payable (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Trade accounts payable $ 54,414 $ 34,770 Payroll liabilities 12,185 10,377 Accrued contract costs 52,847 15,840 Self-insurance accrual 6,601 11,210 Other accrued liabilities 12,114 11,291 Total accounts payable and accrued liabilities $ 138,161 $ 83,488

Debt Obligations (Tables)

Debt Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long Term Debt	The Company’s debt obligations as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Aggregate outstanding principal balance, 2014 Term Loan Facility $ 107,224 $ 92,224 Repayment fee, 2014 Term Loan Facility 9,650 4,611 Unamortized discount – repayment fee, 2014 Term Loan Facility (7,235 ) (3,592 ) Unamortized debt issuance costs, 2014 Term Loan Facility (4,464 ) (4,054 ) Revolver borrowings, 2013 ABL Credit Facility 28,108 — Total debt obligations, net of unamortized discount and debt issuance costs $ 133,283 $ 89,189 Current maturities of long-term debt $ 105,175 $ — Short-term borrowings under revolving credit facility 28,108 — Long-term debt obligations — 89,189 Total debt obligations, net of unamortized discount and debt issuance costs $ 133,283 $ 89,189
Makewhole amounts due in case of prepayment	Should a prepayment in full occur under the Sixth Amendment, the estimated makewhole amount due at future prepayment dates would be as follows (in thousands): March 31, June 30, September 30, December 31, March 31, June 30, September 30, Makewhole $ 16,843 $ 13,358 $ 9,874 $ 16,888 $ 12,331 $ 7,595 $ 3,350
Schedule of Interest Rate Margins	The interest rate margins will be adjusted each quarter based on the Company’s fixed charge coverage ratio as of the end of the previous quarter as follows: Fixed Charge Coverage Ratio U.S. Base Rate, Canadian Base Rate and Canadian Prime Rate Loans LIBOR Loans, BA Rate Loans and Letter of Credit Fees >1.25 to 1 1.25% 2.25% ≤1.25 to 1 and >1.15 to 1 1.50% 2.50% ≤1.15 to 1 1.75% 2.75%
Fair Value of Debt Instruments	The estimated fair value of the Company’s debt instruments as of December 31, 2017 and December 31, 2016 was as follows (in thousands): December 31, 2017 December 31, 2016 2014 Term Loan Facility $ 119,042 $ 95,577 Revolver borrowings, 2013 ABL Credit Facility 28,108 — Total fair value of debt instruments $ 147,150 $ 95,577
Principal Amounts Due under Remaining Debt Obligations	The principal amounts due under the Company’s remaining debt obligations as of December 31, 2017 is as follows (in thousands): Fiscal year: 2018 $ 135,332 $ 135,332

Retirement Plans and Benefits (

Retirement Plans and Benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Plans and Benefits	The following table contains a summary of plan information relating to the Company’s participation in multiemployer pension plans, including Company contributions for the last three years, status of the multiemployer plan, and whether the plan is subject to a funding improvement, rehabilitation plan or contribution surcharges. Information has been presented separately for individually significant plans (defined as plans that make up 70 to 80 percent of the total Company defined benefit contributions and any plan that exceeds individual contributions of $0.1 million in any plan year presented). Fund EIN/PN PPA Plan Year Subject to 2017 2016 2015 Sur-charge Imposed Expiration Pennsylvania Heavy and Highway Contractors Pension Trust 23-6531755/ 001 Green 12/31/2016 No $ 2,085 $ 975 $ 1,086 No 12/31/2018 Boilermaker-Blacksmith National Pension Trust 48-6168020/ 001 Yellow 12/31/2016 Implemented $ — $ — $ 208 No N/A Other Funds — — 43 Total Contributions: $ 2,085 $ 975 $ 1,337 (1) The zone status is based on information that the Company received from the plan as well as publicly available information per the Department of Labor website and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than 65 percent funded, plans in the yellow zone are less than 80 percent funded, and plans in the green zone are at least 80 percent funded. Although the Boilermaker-Blacksmith National Pension Trust plan was considered to be in the yellow zone for 2016, it proactively entered critical status early for 2017 and imposed a surcharge for contributions payable after May 28, 2017. (2) The “Subject to Funding Improvement / Rehabilitation Plan” column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. The last column lists the expiration date(s) of the collective-bargaining agreement(s) to which the plans are subject.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income (Loss) Before Income Taxes on Continuing Operations	Income (loss) before income taxes on continuing operations consists of the following (in thousands): Year Ended December 31, 2017 2016 2015 Foreign $ (4,406 ) $ (556 ) $ 334 United States (103,217 ) (43,756 ) (118,914 ) $ (107,623 ) $ (44,312 ) $ (118,580 )
Provision (Benefit) for Income Taxes on Continuing Operations by Country	Provision (benefit) for income taxes on continuing operations by country consists of the following (in thousands): Year Ended December 31, 2017 2016 2015 Current provision (benefit): Foreign $ (157 ) $ (550 ) $ 1,822 United States: Federal (833 ) 735 (51,475 ) State (391 ) (159 ) (4,497 ) (1,381 ) 26 (54,150 ) Deferred tax provision (benefit): Foreign 417 (556 ) 357 United States — — (238 ) 417 (556 ) 119 Total benefit for income taxes $ (964 ) $ (530 ) $ (54,031 )
Reconciliation of Differences Between Provision (Benefit) for Income Tax Computed and Reported Provision for Income Taxes	A reconciliation of the differences between the provision (benefit) for income taxes computed at the appropriate statutory rates and the reported provision (benefit) for income taxes is as follows (in thousands). For 2017 , 2016 and 2015 , the Company was domiciled in the United States, which has a 35 percent statutory tax rate. 2017 2016 2015 Taxes on earnings at statutory rate in domicile of parent company $ (37,668 ) $ (15,509 ) $ (41,503 ) Earnings taxed at rates less or greater than parent company rates: Foreign 443 246 (297 ) State income taxes, net of U.S. federal benefit — 116 (3,050 ) Non deductibles 3,033 2,017 2,681 Changes in provision for unrecognized tax positions 574 204 91 Change in valuation allowance 33,656 12,951 (19,027 ) Stock-based compensation 597 1,522 1,990 Deferred tax adjustments (276 ) (1,123 ) (595 ) Deemed dividend/previously taxed income — — 1,850 Prior year tax settlement 327 382 (246 ) Transfer pricing allocation (874 ) 6 2,011 Stock issuance costs — — 1,947 Alternative Minimum Tax credit carryforward — (1,031 ) — Other (124 ) (311 ) 117 Tax Cuts and Jobs Act (652 ) — — Total benefit for income taxes $ (964 ) $ (530 ) $ (54,031 )
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	21 percent , which decreased the gross position by $0.9 million with a full offset to the valuation allowance. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2017 2016 Beginning balance $ 2,406 $ 2,406 Impact of Tax Cuts and Jobs Act (870 ) — Other (49 ) — Ending balance $ 1,487 $ 2,406
Summary of Principal Components of Company's Net Deferred Tax Assets (Liabilities)	The principal components of the Company’s net deferred tax assets (liabilities) are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Non-current: Accrued vacation 293 144 Allowance for doubtful accounts 319 249 Estimated losses 2,021 143 Deferred compensation 311 696 Accrued insurance 4,620 7,581 Deferred rent 790 1,815 Various accrued liabilities 163 274 Goodwill 12,885 25,739 U.S. tax net operating loss carry forwards 53,617 59,258 State tax net operating loss carry forwards 8,201 6,148 Foreign tax net operating loss carry forwards 2,817 2,817 Alternative Minimum Tax credit carryforward — 846 Other 211 117 Gross deferred tax assets 86,248 105,827 Valuation allowance (68,003 ) (69,304 ) Deferred tax assets, net of valuation allowance 18,245 36,523 Deferred tax liabilities: Non-current: Term Loan amortization (394 ) (1,203 ) Depreciation (3,150 ) (7,409 ) Intangible amortization (14,701 ) (27,596 ) Deferred tax liabilities (18,245 ) (36,208 ) Net deferred tax assets $ — $ 315 United States $ — $ — Foreign — 315 Net deferred tax assets $ — $ 315

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component	Changes in Accumulated Other Comprehensive Income (Loss) by Component Year Ended December 31, 2017 Foreign currency Changes in Total Balance, December 31, 2016 $ (1,412 ) $ (2,822 ) $ (4,234 ) Other comprehensive income before reclassifications 1,287 — 1,287 Amounts reclassified from accumulated other comprehensive income (loss) — 1,085 1,085 Net current-period other comprehensive income 1,287 1,085 2,372 Balance, December 31, 2017 $ (125 ) $ (1,737 ) $ (1,862 ) Year Ended December 31, 2016 Foreign currency Changes in Total Balance, December 31, 2015 $ (1,965 ) $ (4,044 ) $ (6,009 ) Other comprehensive income before reclassifications 553 — 553 Amounts reclassified from accumulated other comprehensive income (loss) — 1,222 1,222 Net current-period other comprehensive income 553 1,222 1,775 Balance, December 31, 2016 $ (1,412 ) $ (2,822 ) $ (4,234 ) Year Ended December 31, 2015 Foreign currency Changes in Total Balance, December 31, 2014 $ 6,863 $ (4,075 ) $ 2,788 Other comprehensive loss before reclassifications (8,828 ) (2,928 ) (11,756 ) Amounts reclassified from accumulated other comprehensive income (loss) — 2,959 2,959 Net current-period other comprehensive income (loss) (8,828 ) 31 (8,797 ) Balance, December 31, 2015 $ (1,965 ) $ (4,044 ) $ (6,009 )
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	Reclassifications out of Accumulated Other Comprehensive Income (Loss) Year Ended December 31, 2017 Details about Accumulated Other Comprehensive Income Components Amount Details about Accumulated Other Comprehensive Income Components Interest rate contracts $ 1,085 Interest expense, net Total $ 1,085 Year Ended December 31, 2016 Details about Accumulated Other Comprehensive Income Components Amount Details about Accumulated Other Comprehensive Income Components Interest rate contracts $ 1,222 Interest expense, net Total $ 1,222 Year Ended December 31, 2015 Details about Accumulated Other Comprehensive Income Components Amount Details about Accumulated Other Comprehensive Income Components Interest rate contracts $ 2,959 Interest expense, net Total $ 2,959
RSU Activity and Related Information	The Company’s RSU activity and related information consist of: Year Ended December 31, 2017 Shares Weighted-Average Nonvested, beginning of year 1,219,446 $ 3.87 Granted 711,990 2.47 Vested (809,652 ) 4.10 Forfeited (108,137 ) 2.62 Nonvested, end of year 1,013,647 $ 2.84
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following table sets forth the assumptions used in the valuations of these awards: Year Ended December 31, 2017 2016 2015 Volatility 99.8% 91.1% 77.8% Risk-free interest rates 1.37% 1.01% 0.49% - 0.96%

Income (Loss) Per Common Share

Income (Loss) Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Loss Per Common Share	Basic and diluted loss per common share is computed as follows (in thousands, except share and per share amounts): Year Ended December 31, 2017 2016 2015 Net loss from continuing operations applicable to common shares (numerator for basic and diluted calculation) $ (106,659 ) $ (43,782 ) $ (64,549 ) Weighted average number of common shares outstanding for basic loss per share 62,160,849 61,364,592 57,759,988 Weighted average number of potentially dilutive common shares outstanding — — — Weighted average number of common shares outstanding for diluted loss per share 62,160,849 61,364,592 57,759,988 Loss per common share from continuing operations: Basic $ (1.72 ) $ (0.71 ) $ (1.12 ) Diluted $ (1.72 ) $ (0.71 ) $ (1.12 )
Schedule of Potentially Dilutive Shares	The Company has excluded shares potentially issuable under the terms of use of the securities listed below from the number of potentially dilutive shares outstanding as the effect would be anti-dilutive: Year Ended December 31, 2017 2016 2015 Stock options — 32,787 55,000 Restricted stock and restricted stock rights 274,210 519,137 665,955 274,210 551,924 720,955

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of Company's Operations by Reportable Segment	The following tables reflect the Company’s operations for the years ended December 31, 2017 , 2016 and 2015 (in thousands) by its three reportable segments. Year Ended December 31, 2017 Utility T&D Canada Oil & Gas Corporate Eliminations Consolidated Contract revenue $ 506,978 $ 121,151 $ 221,939 $ — $ (85 ) $ 849,983 Contract costs 486,340 115,870 272,613 — (85 ) 874,738 Contract income (loss) 20,638 5,281 (50,674 ) — — (24,755 ) Amortization of intangibles 9,559 — 108 — — 9,667 General and administrative 16,360 7,659 9,584 21,090 — 54,693 Other charges — 1,667 139 420 — 2,226 Operating loss $ (5,281 ) $ (4,045 ) $ (60,505 ) $ (21,510 ) $ — (91,341 ) Non-operating expenses (16,282 ) Benefit for income taxes (964 ) Loss from continuing operations (106,659 ) Loss from discontinued operations, net of provision for income taxes (1,436 ) Net loss $ (108,095 ) Year Ended December 31, 2016 Utility T&D Canada Oil & Gas Corporate Eliminations Consolidated Contract revenue $ 418,387 $ 143,140 $ 170,448 $ — $ (290 ) $ 731,685 Contract costs 378,229 134,248 173,202 — (290 ) 685,389 Contract income (loss) 40,158 8,892 (2,754 ) — — 46,296 Amortization of intangibles 9,559 — 195 — — 9,754 General and administrative 15,035 8,538 12,175 25,245 — 60,993 Other charges (income) (3 ) 1,004 1,659 3,550 — 6,210 Operating income (loss) $ 15,567 $ (650 ) $ (16,783 ) $ (28,795 ) $ — (30,661 ) Non-operating expenses (13,651 ) Benefit for income taxes (530 ) Loss from continuing operations (43,782 ) Loss from discontinued operations, net of provision for income taxes (3,977 ) Net loss $ (47,759 ) Year Ended December 31, 2015 Utility T&D Canada Oil & Gas Corporate Eliminations Consolidated Contract revenue $ 379,629 $ 232,534 $ 297,110 $ — $ (279 ) $ 908,994 Contract costs 354,267 209,439 304,813 — (279 ) 868,240 Contract income (loss) 25,362 23,095 (7,703 ) — — 40,754 Amortization of intangibles 9,559 — 315 — — 9,874 General and administrative 9,841 12,245 20,154 35,095 — 77,335 Gain on sale of subsidiary — — — — — — (12,826 ) Other charges 2,002 624 9,852 5,991 — 18,469 Operating income (loss) $ 3,960 $ 10,226 $ (38,024 ) $ (41,086 ) $ — (52,098 ) Non-operating expenses (66,482 ) Benefit for income taxes (54,031 ) Loss from continuing operations (64,549 ) Income from discontinued operations, net of provision for income taxes 96,032 Net income $ 31,483 Depreciation and amortization expense by segment are presented below (in thousands): Year Ended December 31, 2017 2016 2015 Utility T&D $ 15,300 $ 16,511 $ 18,719 Canada 737 924 1,321 Oil & Gas 2,041 3,142 5,241 Corporate 1,084 1,342 1,919 Total $ 19,162 $ 21,919 $ 27,200 Capital expenditures by segment are presented below (in thousands): Year Ended December 31, 2017 2016 2015 Utility T&D $ 1,953 $ 2,493 $ 451 Canada 271 693 519 Oil & Gas 275 323 605 Corporate 62 293 608 Total $ 2,561 $ 3,802 $ 2,183 Total assets by segment as of December 31, 2017 and 2016 are presented below (in thousands): Year Ended December 31, 2017 2016 Utility T&D $ 196,923 $ 201,339 Canada 41,958 47,704 Oil & Gas 50,779 42,887 Corporate 73,893 70,601 Total assets, continuing operations $ 363,553 $ 362,531
Total Contract Revenue	Customers representing 10 percent or more of total contract revenue are as follows: Year Ended December 31, 2017 2016 2015 Oncor 25.0 % 25.0 % 17.9 % Enterprise Products Partners L.P. 9.8 % 9.4 % 12.5 %
Information about the Company's Operation	Information about the Company’s operations in its work countries is shown below (in thousands): Year Ended December 31, 2017 2016 2015 Contract revenue: United States $ 728,832 $ 588,545 $ 676,460 Canada 121,151 143,140 232,534 $ 849,983 $ 731,685 $ 908,994 Year Ended December 31, 2017 2016 Property, plant and equipment, net: United States $ 25,804 $ 33,625 Canada 4,309 4,498 $ 30,113 $ 38,123

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Derivative Instruments, Effect on Other Comprehensive Income (Loss)	For the Year Ended December 31, Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Gain Recognized in OCI on Derivative (Effective Portion) Financial Statement Classification Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion) 2017 2016 2015 2017 2016 2015 Interest rate contracts $ — $ — $ (2,928 ) Interest expense, net $ 1,085 $ 1,222 $ 2,959 Total $ — $ — $ (2,928 ) $ 1,085 $ 1,222 $ 2,959

Other Charges (Tables)

Other Charges (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The following table reflects the Company’s other charges for the years ended December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 Equipment and facility lease abandonment (1) $ (225 ) $ 3,633 $ 7,747 Loss on disposal of equipment (2) — 1,030 6,683 Employee severance charges 1,564 1,300 1,728 Restatement costs (3) 636 (24 ) 595 Impairment of intangible assets (4) — — 534 Accelerated stock vesting 251 271 1,182 Total $ 2,226 $ 6,210 $ 18,469 (1) Includes $0.0 million , $0.8 million and $1.8 million of costs associated with the write-off of deferred rent attributed to the abandonment of a portion of the Company’s corporate facility lease headquarters during the years ended December 31, 2017 , 2016 and 2015 , respectively. In addition, the 2017 amount includes a $0.8 million adjustment to decrease one of the Company’s lease abandonment liabilities. (2) 2016 loss is attributed to the fourth quarter disposal of $0.7 million in equipment associated with the abandonment of a portion of the Company’s corporate facility lease headquarters, as well as the $0.3 million loss on sale of the Oil & Gas segment’s fabrication business that was finalized during the year. 2015 loss is attributed to a $2.2 million loss on the sale of a corporate asset, impairment charges of $2.0 million in relation to the Oil & Gas segment’s fabrication services which was sold in 2016, impairment charges of $1.3 million in relation to construction equipment in the Utility T&D segment and the disposal of $1.2 million in equipment associated with the abandonment of a portion of the Company’s corporate facility lease headquarters. (3) Includes accounting and legal fees associated with the investigation of the root cause behind the deterioration of certain construction projects within the Oil & Gas segment, which led to the restatements of the Company’s Condensed Consolidated Financial Statements for the quarterly periods ended March 31, 2014 and June 30, 2014. (4) Attributed to intangible assets associated with fabrication, field and union construction turnaround services in the Oil & Gas segment.
Schedule of Restructuring Reserve by Type of Cost	Activity in the accrual related to the equipment and facility lease abandonment charges during the year ended December 31, 2017 is as follows (in thousands): Utility T&D Canada Oil & Gas Corporate Total Accrued cost at December 31, 2016 $ 348 $ 290 $ 793 $ 4,048 $ 5,479 Cash payments (176 ) (120 ) (296 ) (1,127 ) (1,719 ) Non-cash charges (1) — — — 340 340 Change in estimates — 41 48 (314 ) (225 ) Accrued cost at December 31, 2017 $ 172 $ 211 $ 545 $ 2,947 $ 3,875 (1) Non-cash charges consist of accretion expense.

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Major Classes of Revenue and Income (Losses) with Respect to Discontinued Operations	Components of assets held for sale as of December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Accounts receivable, net $ 490 $ 7,806 Contract cost and recognized income not yet billed 234 136 Prepaid expenses and other assets 36 61 Parts and supplies inventories 409 468 Property, plant and equipment, net 375 318 Intangible assets, net 260 260 Other long-term assets — 1 Total assets held for sale 1,804 9,050 Accounts payable and accrued liabilities 100 3,789 Contract billings in excess of cost and recognized income 765 4,480 Other current liabilities — 3 Other long-term liabilities — 3 Total liabilities held for sale $ 865 $ 8,275 Condensed Statements of Operations of the Discontinued Operations for the years ended December 31, 2017 , 2016 and 2015 are as follows (in thousands): Year Ended December 31, 2017 Professional Services Hawkeye Other Total Contract revenue $ 1,006 $ — $ — $ 1,006 Contract costs 831 — — 831 General and administrative 1,219 (197 ) — 1,022 Other charges 525 — — 525 Operating income (loss) (1,569 ) 197 — (1,372 ) Non-operating income (expense) — — — — Pre-tax income (loss) (1,569 ) 197 — (1,372 ) Provision for income taxes 64 — — 64 Income (loss) from discontinued operations $ (1,633 ) $ 197 $ — $ (1,436 ) Year Ended December 31, 2016 Professional Services Hawkeye Other Total Contract revenue $ 2,126 $ — $ — $ 2,126 Contract costs 2,299 — — 2,299 Loss on sale of subsidiary 2,456 — — 2,456 General and administrative 2,633 (313 ) — 2,320 Other income (1,060 ) — — (1,060 ) Operating income (loss) (4,202 ) 313 — (3,889 ) Non-operating income (expense) — — — — Pre-tax income (loss) (4,202 ) 313 — (3,889 ) Provision for income taxes — — 88 88 Income (loss) from discontinued operations $ (4,202 ) $ 313 $ (88 ) $ (3,977 ) Year Ended December 31, 2015 Professional Services Hawkeye Other Total Contract revenue $ 229,482 $ 2,078 $ — $ 231,560 Contract costs 197,414 1,317 — 198,731 Amortization of intangibles 793 — — 793 Gain on sale of subsidiaries (152,208 ) — — (152,208 ) General and administrative 26,937 (370 ) — 26,567 Other charges 4,405 — — 4,405 Operating income 152,141 1,131 — 153,272 Non-operating income (expense) (36 ) 6 — (30 ) Pre-tax income 152,105 1,137 — 153,242 Provision for income taxes 57,210 — — 57,210 Income from discontinued operations $ 94,895 $ 1,137 $ — $ 96,032 Condensed Balance Sheets of the Discontinued Operations are as follows (in thousands): December 31, 2017 Professional Services Hawkeye Total Contract cost and recognized income not yet billed $ 324 $ — $ 324 Total assets associated with discontinued operations 324 — 324 Accounts payable and accrued liabilities 337 180 517 Other current liabilities 574 — 574 Other long-term liabilities 893 — 893 Total liabilities associated with discontinued operations 1,804 180 1,984 Net liabilities associated with discontinued operations $ (1,480 ) $ (180 ) $ (1,660 ) December 31, 2016 Professional Services Hawkeye Total Accounts receivable, net $ 313 $ — $ 313 Contract cost and recognized income not yet billed 192 — 192 Total assets associated with discontinued operations 505 — 505 Accounts payable and accrued liabilities 412 277 689 Contract billings in excess of costs 358 — 358 Other current liabilities 531 — 531 Other long-term liabilities 995 — 995 Total liabilities associated with discontinued operations 2,296 277 2,573 Net liabilities associated with discontinued operations $ (1,791 ) $ (277 ) $ (2,068 )

Quarterly Financial Data (Una45

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	Selected unaudited quarterly financial data for the years ended December 31, 2017 and 2016 is presented below (in thousands): Year 2017 Quarter Ended March 31, 2017 June 30, 2017 September 30, 2017 December 31, 2017 Total 2017 Contract revenue $ 163,900 $ 227,447 $ 240,773 $ 217,863 $ 849,983 Contract income (loss) 1,681 17,079 (12,188 ) (31,327 ) (24,755 ) Operating income (loss) (14,853 ) 358 (27,789 ) (49,057 ) (91,341 ) Loss from continuing operations before income taxes (18,336 ) (3,318 ) (31,577 ) (54,392 ) (107,623 ) Loss from continuing operations (17,736 ) (1,121 ) (32,709 ) (55,093 ) (106,659 ) Income (loss) from discontinued operations, net of provision for income taxes (31 ) 19 (1,496 ) 72 (1,436 ) Net loss $ (17,767 ) $ (1,102 ) $ (34,205 ) $ (55,021 ) $ (108,095 ) Basic loss per share attributable to Company shareholders: Loss from continuing operations $ (0.29 ) $ (0.02 ) $ (0.52 ) $ (0.89 ) $ (1.72 ) Loss from discontinued operations — — (0.02 ) — (0.02 ) Net loss $ (0.29 ) $ (0.02 ) $ (0.54 ) $ (0.89 ) $ (1.74 ) Diluted loss per share attributable to Company shareholders: Loss from continuing operations $ (0.29 ) $ (0.02 ) $ (0.52 ) $ (0.89 ) $ (1.72 ) Loss from discontinued operations — — (0.02 ) — (0.02 ) Net loss $ (0.29 ) $ (0.02 ) $ (0.54 ) $ (0.89 ) $ (1.74 ) Weighted average number of common shares outstanding Basic 61,829,768 62,170,910 62,310,191 62,329,614 62,160,849 Diluted 61,829,768 62,170,910 62,310,191 62,329,614 62,160,849 Year 2016 Quarter Ended March 31, 2016 June 30, 2016 September 30, 2016 December 31, 2016 Total 2016 Contract revenue $ 199,030 $ 193,442 $ 174,821 $ 164,392 $ 731,685 Contract income 13,799 15,157 12,015 5,325 46,296 Operating loss (9,461 ) (2,741 ) (6,319 ) (12,140 ) (30,661 ) Loss from continuing operations before income taxes (13,131 ) (5,574 ) (9,869 ) (15,738 ) (44,312 ) Loss from continuing operations (13,298 ) (5,761 ) (10,661 ) (14,062 ) (43,782 ) Loss from discontinued operations, net of provision for income taxes (1,853 ) (658 ) (1,325 ) (141 ) (3,977 ) Net loss $ (15,151 ) $ (6,419 ) $ (11,986 ) $ (14,203 ) $ (47,759 ) Basic loss per share attributable to Company shareholders: Loss from continuing operations $ (0.22 ) $ (0.09 ) $ (0.17 ) $ (0.23 ) $ (0.71 ) Loss from discontinued operations (0.03 ) (0.01 ) (0.02 ) — (0.06 ) Net loss $ (0.25 ) $ (0.10 ) $ (0.19 ) $ (0.23 ) $ (0.77 ) Diluted loss per share attributable to Company shareholders: Loss from continuing operations $ (0.22 ) $ (0.09 ) $ (0.17 ) $ (0.23 ) $ (0.71 ) Loss from discontinued operations (0.03 ) (0.01 ) (0.02 ) — (0.06 ) Net loss $ (0.25 ) $ (0.10 ) $ (0.19 ) $ (0.23 ) $ (0.77 ) Weighted average number of common shares outstanding Basic 60,756,314 61,299,334 61,639,590 61,682,996 61,364,592 Diluted 60,756,314 61,299,334 61,639,590 61,682,996 61,364,592

Company Description and Finan46

Company Description and Financial Condition (Details) $ / shares in Units, $ in Thousands	Mar. 27, 2018USD ($)	Mar. 26, 2018USD ($)$ / shares	Jan. 09, 2018Project	Dec. 31, 2017USD ($)Segment	Dec. 31, 2016USD ($)
Subsequent Event [Line Items]
Contract duration, upper limit, more than				2 years
Number of reportable segments | Segment				3
Total debt obligations, net of unamortized discount and debt issuance costs				$ 133,283	$ 89,189
Subsequent Event
Subsequent Event [Line Items]
Number of pipeline projects retained | Project			3
Number of projects to reach mechanical completion | Project			2
Revolver borrowings | Initial First Out Loan | Subsequent Event
Subsequent Event [Line Items]
Loans incurred during merger	$ 10,000	$ 10,000
Revolver borrowings | Additional First Out Loans | Subsequent Event
Subsequent Event [Line Items]
Loans incurred during merger	10,000	10,000
Revolver borrowings | 2014 Term Loan | Subsequent Event
Subsequent Event [Line Items]
Loans incurred during merger	1,100	1,100
Payment of total amendment expenses	$ 100,000	$ 100,000
Primoris | Subsequent Event
Subsequent Event [Line Items]
Price per share paid in merger | $ / shares		$ 0.60
Termination fee		$ 4,300
Termination fee for certain other circumstances		$ 8,000

Summary of Significant Accoun47

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in Accounting Estimate [Line Items]
Number of balance days due									90 days
Obsolescence allowances	$ 0				$ 0				$ 0	$ 0
Operating income (loss)	(49,057,000)	$ (27,789,000)	$ 358,000	$ (14,853,000)	(12,140,000)	$ (2,741,000)	$ (9,461,000)	$ (6,319,000)	(91,341,000)	(30,661,000)	$ (52,098,000)
Income recovery due to change in contract estimate									2,000,000
Deductible insurance claims for workers									1,000,000
Deductible non-union employee-related health care benefit plan									300,000
Allowance for doubtful accounts	2,796,000				1,963,000				$ 2,796,000	1,963,000
Maturity period of liquid investments (or less)									3 months
Short term investment maturity period minimum									3 months
Short term investment	0				0				$ 0	0
Deferred Tax Assets, Gross	86,248,000				105,827,000				86,248,000	105,827,000
Restricted cash	$ 40,367,000				40,206,000				40,367,000	40,206,000
ASU 2016-09
Change in Accounting Estimate [Line Items]
Deferred Tax Assets, Gross					1,800,000					1,800,000
Cumulative effect of new accounting principle					$ 0					0
Change In Contract Estimates
Change in Accounting Estimate [Line Items]
Operating income (loss)									$ 1,400,000	$ 7,600,000

Summary of Significant Accoun48

Summary of Significant Accounting Policies - Schedule of Property Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	20 years
Marine equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	10 years
Minimum | Construction equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	3 years
Minimum | Furniture and equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	3 years
Minimum | Transportation equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	3 years
Maximum | Construction equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	20 years
Maximum | Furniture and equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	12 years
Maximum | Transportation equipment
Property, Plant and Equipment [Line Items]
Useful life of the step up related to PP&E	17 years

Accounts Receivable, Net (Detai

Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 144,988	$ 114,000
Less: allowance for doubtful accounts	(2,796)	(1,963)
Total accounts receivable, net	142,192	112,037
Unbilled revenue
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	22,018	20,447
Trade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	95,923	79,348
Contract retention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	26,146	12,091
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 901	$ 2,114

Accounts Receivable - Additiona

Accounts Receivable - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for bad debt	$ 887	$ 284	$ 2,945
General and administrative expenses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for bad debt	$ 900	$ 300	$ 2,900

Contracts in Progress - Schedul

Contracts in Progress - Schedule of Contract Cost and Recognized Income Not Yet Billed and Related Amounts (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Contractors [Abstract]
Cost incurred on contracts in progress	$ 445,029	$ 234,544
Recognized income	(14,536)	28,702
Contract cost in excess of cost and recognized income	430,493	263,246
Progress billings and advance payments	(434,315)	(256,246)
Total Contract in progress	(3,822)	7,000
Contract cost and recognized income not yet billed	13,992	11,938
Contract billings in excess of cost and recognized income	(17,814)	(4,938)
Net cost of contracts in progress	$ (3,822)	$ 7,000

Contracts in Progress - Additio

Contracts in Progress - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Contractors [Abstract]
Contract cost and recognized income not yet billed on completed agreements	$ 0.5	$ 0.5

Assets Held For Sale - Componen

Assets Held For Sale - Components of assets held for sale (Details) - USD ($) $ in Thousands	Jan. 02, 2018	Dec. 31, 2017	Dec. 31, 2016
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Accounts receivable, net		$ 490	$ 7,806
Contract cost and recognized income not yet billed		234	136
Prepaid expenses and other assets		36	61
Parts and supplies inventories		409	468
Property, plant and equipment, net		375	318
Intangible assets, net		260	260
Other long-term assets		0	1
Total assets		1,804	9,050
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Accounts payable and accrued liabilities		100	3,789
Contract billings in excess of cost and recognized income		765	4,480
Other current liabilities		0	3
Other long-term liabilities		0	3
Total liabilities		$ 865	$ 8,275
Subsequent Event
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Gain on sale of tank services business	$ 3,000

Property, Plant and Equipment -

Property, Plant and Equipment - Total property, plant and equipment, net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 148,159	$ 163,104
Less: accumulated depreciation	(118,046)	(124,981)
Total property, plant and equipment, net	30,113	38,123
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	57,195	59,607
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	26,002	30,752
Land and buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,715	1,521
Transportation equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	57,346	65,501
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,819	5,641
Marine equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 82	$ 82

Property, Plant and Equipment55

Property, Plant and Equipment - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Construction in progress	$ 300	$ 800
Depreciation expense included in operating expense	19,162	21,919	$ 27,200
Operating Expense
Property, Plant and Equipment [Line Items]
Depreciation expense included in operating expense	$ 9,500	$ 12,100	$ 17,300

Intangible Assets - Schedule of

Intangible Assets - Schedule of Changes in the Carrying Amounts of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-lived Intangible Assets [Roll Forward]
Beginning Balance	$ 76,848	$ 86,862
Amortization	(9,667)	(9,754)	$ (9,874)
Transfer to assets held for sale		(260)
Ending Balance	67,181	76,848	86,862
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Beginning Balance	73,100	82,044
Amortization	(8,597)	(8,684)
Transfer to assets held for sale		(260)
Ending Balance	$ 64,503	$ 73,100	82,044
Weighted average remaining amortization period	7 years 6 months	8 years 6 months
Trademark/ Tradename
Finite-lived Intangible Assets [Roll Forward]
Beginning Balance	$ 3,748	$ 4,818
Amortization	(1,070)	(1,070)
Transfer to assets held for sale		0
Ending Balance	$ 2,678	$ 3,748	$ 4,818
Weighted average remaining amortization period	2 years 6 months	3 years 6 months

Intangible Assets - Narrative (

Intangible Assets - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Amortization of intangibles	$ 9,667	$ 9,754	$ 9,874
Minimum
Restructuring Cost and Reserve [Line Items]
Estimated useful lives of intangible asset	5 years
Maximum
Restructuring Cost and Reserve [Line Items]
Estimated useful lives of intangible asset	15 years

Intangible Assets - Estimated A

Intangible Assets - Estimated Amortization Expense (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fiscal year:
2,018	$ 9,667
2,019	9,667
2,020	9,135
2,021	8,597
2,022	8,597
Thereafter	21,518
Total amortization	$ 67,181	$ 76,848	$ 86,862

Accounts Payable and accrued li

Accounts Payable and accrued liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable Balance Sheet Location [Line Items]
Trade accounts payable	$ 54,414	$ 34,770
Payroll liabilities	12,185	10,377
Accrued contract costs	52,847	15,840
Self-insurance accrual	6,601	11,210
Other accrued liabilities	12,114	11,291
Total accounts payable and accrued liabilities	138,161	83,488
Provisions on loss projects	12,200	3,700
Short-term liabilities
Accounts Payable Balance Sheet Location [Line Items]
Self-insurance accrual	6,600	11,200
Other long-term liabilities
Accounts Payable Balance Sheet Location [Line Items]
Self-insurance accrual, long-term	$ 17,200	$ 14,500

Debt Obligations - Schedule of

Debt Obligations - Schedule of Debt Obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long term debt	$ 133,283	$ 89,189
Current maturities of long-term debt	105,175	0
Short-term borrowings under revolving credit facility	28,108	0
Long-term debt obligations	0	89,189
Total debt obligations, net of unamortized discount and debt issuance costs	133,283	89,189
Revolver borrowings
Debt Instrument [Line Items]
Long term debt	28,108	0
2014 Term Loan
Debt Instrument [Line Items]
Repayment fee, 2014 Term Loan Facility	9,650	4,611
Unamortized discount – repayment fee, 2014 Term Loan Facility	(7,235)	(3,592)
Unamortized debt issuance costs, 2014 Term Loan Facility	(4,464)	(4,054)
Long term debt	$ 107,224	$ 92,224

Debt Obligations - Narrative (D

Debt Obligations - Narrative (Detail) - USD ($)

Mar. 27, 2018

Mar. 26, 2018

Jan. 02, 2018

Sep. 28, 2015

Mar. 31, 2015

Dec. 15, 2014

Aug. 07, 2013

Jan. 31, 2018

Mar. 31, 2016

Dec. 31, 2015

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Short-term Debt [Line Items]

Payments on debt obligations

$ 0

$ 3,128,000

$ 174,648,000

Minimum amount of debt obligation that will lead to change of control and insolvency percentage

15,000,000

2014 Term Loan

Short-term Debt [Line Items]

Repayment fee, 2014 Term Loan Facility

9,650,000

4,611,000

Unamortized discount - repayment fee, 2014 Term Loan Facility

7,235,000

3,592,000

Unamortized debt issuance costs, 2014 Term Loan Facility

4,464,000

4,054,000

2014 Term Loan

Short-term Debt [Line Items]

Shares issued as consideration for suspension of covenant testing (in shares)

10,100,000

Percent of outstanding shares issued

19.90%

Debt extinguishment costs

$ 33,500,000

Debt extinguishment charges

$ 800,000

Amendment fees paid

$ 2,300,000

$ 4,600,000

Consolidated EBITDA multiplier

2

Payments on debt obligations

$ 3,100,000

$ 93,600,000

ABL Credit Facility

Short-term Debt [Line Items]

Expiration period

5 years

Debt instrument, maturity date

Aug. 7, 2018

Sublimit for letters of credit

$ 80,000,000

Threshold percentage for commitment fee

50.00%

Fronting fee percentage

0.125%

ABL Credit Facility | U.S. Facility

Short-term Debt [Line Items]

Debt, principal amount

$ 90,000,000

$ 80,000,000

ABL Credit Facility | Canadian Facility

Short-term Debt [Line Items]

Debt, principal amount

10,000,000

10,000,000

Revolving Credit Facility | Minimum

Short-term Debt [Line Items]

Unused availability on credit facility

$ 10,000,000

Revolving Credit Facility | Five consecutive days | Minimum

Short-term Debt [Line Items]

Unused availability on credit facility

15,000,000

Excess availability period

5 days

Revolving Credit Facility | Anytime | Minimum

Short-term Debt [Line Items]

Unused availability on credit facility

12,500,000

JP Morgan Chase Bank NA and KKR Credit Advisors (US) LLC | 2014 Term Loan

Short-term Debt [Line Items]

Expiration period

5 years

Debt, principal amount

$ 270,000,000

Additional loan amount

$ 15,000,000

Effective interest rate

13.00%

11.00%

Repayment fee, 2014 Term Loan Facility

$ 4,600,000

$ 9,700,000

Prepayment penalty

5.00%

9.00%

Unamortized discount - repayment fee, 2014 Term Loan Facility

$ 7,200,000

$ 3,600,000

Debt extinguishment costs

0

100,000

Unamortized debt issuance costs, 2014 Term Loan Facility

4,500,000

4,100,000

Payments on debt obligations

0

$ 3,100,000

Outstanding revolver borrowings

$ 107,200,000

JP Morgan Chase Bank NA and KKR Credit Advisors (US) LLC | 2014 Term Loan | Minimum

Short-term Debt [Line Items]

Interest rate floor

1.25%

JP Morgan Chase Bank NA and KKR Credit Advisors (US) LLC | 2014 Term Loan | Base Rate

Short-term Debt [Line Items]

Basis spread on variable rate

8.75%

JP Morgan Chase Bank NA and KKR Credit Advisors (US) LLC | 2014 Term Loan | Eurodollar Rate

Short-term Debt [Line Items]

Basis spread on variable rate

9.75%

11.75%

9.75%

Bank of America, N.A. | ABL Credit Facility

Short-term Debt [Line Items]

Debt, principal amount

$ 100,000,000

$ 90,000,000

Current line of credit

$ 28,100,000

Borrowing base, percent of eligible accounts receivable

85.00%

Borrowing base, percent of unbilled accounts receivable

75.00%

Borrowing base, limit on eligible unbilled accounts receivable

$ 33,000,000

Borrowing base, limit on milestone buildings, retainage and other performance-based benchmarks

23,000,000

Minimum fixed charge coverage ratio, covenants requirements

1.15

Bank of America, N.A. | ABL Credit Facility | Cash | Maximum

Short-term Debt [Line Items]

Cash collateral amount

$ 25,000,000

Bank of America, N.A. | ABL Credit Facility | Preceding calendar month is less than 50% of the commitments

Short-term Debt [Line Items]

Commitment fee percentage

50.00%

Bank of America, N.A. | ABL Credit Facility | Usage equals or exceeds 50% of the commitments for the period

Short-term Debt [Line Items]

Commitment fee percentage

37.50%

Bank of America, N.A. | ABL Credit Facility | Five consecutive days | Minimum

Short-term Debt [Line Items]

Excess availability threshold percentage

15.00%

Bank of America, N.A. | ABL Credit Facility | Anytime | Minimum

Short-term Debt [Line Items]

Excess availability threshold percentage

12.50%

Letter of Credit | Bank of America, N.A. | ABL Credit Facility | Cash

Short-term Debt [Line Items]

Cash collateral amount

$ 40,000,000

March 31, 2018 | 2014 Term Loan

Short-term Debt [Line Items]

Maximum leverage ratio

5.50

Minimum interest coverage ratio

1.75

June 30, 2018 | 2014 Term Loan

Short-term Debt [Line Items]

Maximum leverage ratio

4.50

Minimum interest coverage ratio

2

December 31, 2018 | 2014 Term Loan

Short-term Debt [Line Items]

Minimum interest coverage ratio

1.50

September 30, 2018 | 2014 Term Loan

Short-term Debt [Line Items]

Maximum leverage ratio

4.25

March 31, 2019 | 2014 Term Loan

Short-term Debt [Line Items]

Maximum leverage ratio

3

Minimum interest coverage ratio

2.75

Subsequent Event | ABL Credit Facility

Short-term Debt [Line Items]

Payments on debt obligations

$ 2,500,000

Unused availability on credit facility

$ 12,800,000

Subsequent Event | Bank of America, N.A. | ABL Credit Facility

Short-term Debt [Line Items]

Payments on debt obligations

$ 2,500,000

Subsequent Event | Initial First Out Loan | Revolver borrowings

Short-term Debt [Line Items]

Debt, principal amount

$ 10,000,000

$ 10,000,000

Subsequent Event | Additional First Out Loans | Revolver borrowings

Short-term Debt [Line Items]

Debt, principal amount

10,000,000

10,000,000

Subsequent Event | 2014 Term Loan | Revolver borrowings

Short-term Debt [Line Items]

Debt, principal amount

1,100,000

1,100,000

Payment of total amendment expenses

$ 100,000,000

$ 100,000,000

Debt Obligations - Makewhole am

Debt Obligations - Makewhole amounts due in future quarters (Details) - JP Morgan Chase Bank NA and KKR Credit Advisors (US) LLC - 2014 Term Loan $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
March 31, 2018
Debt Instrument [Line Items]
Makewhole amount	$ 16,843
June 30, 2018
Debt Instrument [Line Items]
Makewhole amount	13,358
September 30, 2018
Debt Instrument [Line Items]
Makewhole amount	9,874
December 31, 2018
Debt Instrument [Line Items]
Makewhole amount	16,888
March 31, 2019
Debt Instrument [Line Items]
Makewhole amount	12,331
June 30, 2019
Debt Instrument [Line Items]
Makewhole amount	7,595
September 30, 2019
Debt Instrument [Line Items]
Makewhole amount	$ 3,350

Debt Obligations - Schedule o63

Debt Obligations - Schedule of Interest Rate Margins (Detail)	12 Months Ended
	Dec. 31, 2017
Greater than 1.25 to 1
Debt Instrument [Line Items]
Fixed charge coverage ratio	1.25
Greater than 1.25 to 1 | U.S. Base Rate, Canadian Base Rate and Canadian Prime Rate Loans
Debt Instrument [Line Items]
LIBOR and BA Equivalent Rate Loans and Letter of Credit Fees	1.25%
Greater than 1.25 to 1 | LIBOR Loans, BA Rate Loans and Letter of Credit Fees
Debt Instrument [Line Items]
LIBOR and BA Equivalent Rate Loans and Letter of Credit Fees	2.25%
1.25 to 1 and 1.15 to 1 | Minimum
Debt Instrument [Line Items]
Fixed charge coverage ratio	1.15
1.25 to 1 and 1.15 to 1 | Maximum
Debt Instrument [Line Items]
Fixed charge coverage ratio	1.25
1.25 to 1 and 1.15 to 1 | U.S. Base Rate, Canadian Base Rate and Canadian Prime Rate Loans
Debt Instrument [Line Items]
LIBOR and BA Equivalent Rate Loans and Letter of Credit Fees	1.50%
1.25 to 1 and 1.15 to 1 | LIBOR Loans, BA Rate Loans and Letter of Credit Fees
Debt Instrument [Line Items]
LIBOR and BA Equivalent Rate Loans and Letter of Credit Fees	2.50%
1.15 to 1
Debt Instrument [Line Items]
Fixed charge coverage ratio	1.15
1.15 to 1 | U.S. Base Rate, Canadian Base Rate and Canadian Prime Rate Loans
Debt Instrument [Line Items]
LIBOR and BA Equivalent Rate Loans and Letter of Credit Fees	1.75%
1.15 to 1 | LIBOR Loans, BA Rate Loans and Letter of Credit Fees
Debt Instrument [Line Items]
LIBOR and BA Equivalent Rate Loans and Letter of Credit Fees	2.75%

Debt Obligations - Fair Value o

Debt Obligations - Fair Value of Debt Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total fair value of debt instruments	$ 147,150	$ 95,577
2014 Term Loan
Debt Instrument [Line Items]
Total fair value of debt instruments	119,042	95,577
Revolver borrowings
Debt Instrument [Line Items]
Total fair value of debt instruments	$ 28,108	$ 0

Debt Obligations - Principal Am

Debt Obligations - Principal Amounts Due under Remaining Debt Obligations (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Debt Disclosure [Abstract]
2,018	$ 135,332
Total	$ 135,332

Retirement Plans and Benefits -

Retirement Plans and Benefits - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Multiemployer Plans [Line Items]
Percentage limit of total plan contributions	5.00%
Contributions to defined contribution plans	$ 9.1	$ 6.9	$ 9.9
Minimum
Multiemployer Plans [Line Items]
Percentage limit of total plan contributions	70.00%
Limit of individual contributions of plan	$ 0.1
Maximum
Multiemployer Plans [Line Items]
Percentage limit of total plan contributions	80.00%

Retirement Plans and Benefits67

Retirement Plans and Benefits - Summary of plan information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Multiemployer Plans [Line Items]
Contributions	$ 2,085	$ 975	$ 1,337
Pennsylvania Heavy and Highway Contractors Pension Trust
Multiemployer Plans [Line Items]
EIN/PN	23-6531755/ 001
PPA Zone Status	Green
Plan Year End for Zone Status	Dec. 31, 2016
Subject to Funding Improvement/ Rehabilitation Plan	No
Contributions	$ 2,085	975	1,086
Sur-charge Imposed	No
Expiration Date of Collective Bargaining Agreement	Dec. 31, 2018
Boilermaker-Blacksmith National Pension Trust
Multiemployer Plans [Line Items]
EIN/PN	48-6168020/ 001
PPA Zone Status	Yellow
Plan Year End for Zone Status	Dec. 31, 2016
Subject to Funding Improvement/ Rehabilitation Plan	Implemented
Contributions	$ 0	0	208
Sur-charge Imposed	No
Other Funds
Multiemployer Plans [Line Items]
Contributions	$ 0	$ 0	$ 43

Income Taxes - Income (Loss) Be

Income Taxes - Income (Loss) Before Income Taxes on Continuing Operations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Foreign									$ (4,406)	$ (556)	$ 334
United States									(103,217)	(43,756)	(118,914)
Loss from continuing operations before income taxes	$ (54,392)	$ (31,577)	$ (3,318)	$ (18,336)	$ (15,738)	$ (5,574)	$ (13,131)	$ (9,869)	$ (107,623)	$ (44,312)	$ (118,580)

Income Taxes - Provision (Benef

Income Taxes - Provision (Benefit) for Income Taxes on Continuing Operations by Country (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current provision (benefit):
Foreign	$ (157)	$ (550)	$ 1,822
Federal	(833)	735	(51,475)
State	(391)	(159)	(4,497)
Total	(1,381)	26	(54,150)
Deferred tax provision (benefit):
Foreign	417	(556)	357
United States	0	0	(238)
Total deferred tax expense (benefit)	417	(556)	119
Total benefit for income taxes	$ (964)	$ (530)	$ (54,031)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Income Taxes [Line Items]
Decrease in valuation allowance	$ 36,600
Increase (decrease) in deferred taxes due to ASC 740-10	(1,300)
Tax Cuts and Jobs Act of 2017, Income tax expense (benefit)	(700)
Provision for income tax, discontinued operation	0	$ 100	$ 57,200
Provision (benefit) for income taxes	(964)	(530)	(54,031)
Net provision (benefit) for income taxes	(1,000)	(400)	3,200
Impact of Tax Cuts and Jobs Act	(870)	0
Tax Cuts and Jobs Act of 2017, unrecognized tax benefits that would affect tax rate if recognized	0
Tax Cuts and Jobs Act of 2017, Remeasurement of interest and penalties	400
Recognized interest expense	200	200	$ 200
Accrued interest on income tax	1,000	1,200
Valuation allowance	68,003	69,304
U.S. tax net operating loss carry forwards	53,617	59,258
State tax net operating loss carry forwards	8,201	6,148
Foreign tax net operating loss carry forwards	$ 2,817	2,817
Expiry period of net operating losses	20 years
Domestic
Schedule Of Income Taxes [Line Items]
U.S. tax net operating loss carry forwards	$ 53,600
State and Local
Schedule Of Income Taxes [Line Items]
State tax net operating loss carry forwards	8,200
Foreign
Schedule Of Income Taxes [Line Items]
Foreign tax net operating loss carry forwards	2,800
United States
Schedule Of Income Taxes [Line Items]
Valuation allowance	$ 64,700	66,500
Canada
Schedule Of Income Taxes [Line Items]
Corporate income tax rate	27.00%
Valuation allowance	$ 500	0
Australia
Schedule Of Income Taxes [Line Items]
Valuation allowance	2,800	$ 2,800
Lapse of Statute or Settlement of Audits
Schedule Of Income Taxes [Line Items]
Unrecognized tax benefits expected to be recognized in next twelve months	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Differences Between Provision (Benefit) for Income Tax Computed and Reported Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Taxes on earnings at statutory rate in domicile of parent company	$ (37,668)	$ (15,509)	$ (41,503)
Earnings taxed at rates less or greater than parent company rates:
Foreign	443	246	(297)
State income taxes, net of U.S. federal benefit	0	116	(3,050)
Non deductibles	3,033	2,017	2,681
Changes in provision for unrecognized tax positions	574	204	91
Change in valuation allowance	33,656	12,951	(19,027)
Stock-based compensation	597	1,522	1,990
Deferred tax adjustments	(276)	(1,123)	(595)
Deemed dividend/previously taxed income	0	0	1,850
Prior year tax settlement	327	382	(246)
Transfer pricing allocation	(874)	6	2,011
Stock issuance costs	0	0	1,947
Alternative Minimum Tax credit carryforward	0	(1,031)	0
Other	(124)	(311)	117
Tax Cuts and Jobs Act	(652)	0	0
Total benefit for income taxes	$ (964)	$ (530)	$ (54,031)

Income Taxes - Reconciliation72

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 2,406	$ 2,406
Impact of Tax Cuts and Jobs Act	(870)	0
Other	(49)	0
Ending Balance	$ 1,487	$ 2,406

Income Taxes - Summary of Princ

Income Taxes - Summary of Principal Components of Company's Net Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Non-current:
Accrued vacation	$ 293	$ 144
Allowance for doubtful accounts	319	249
Estimated losses	2,021	143
Deferred compensation	311	696
Accrued insurance	4,620	7,581
Deferred rent	790	1,815
Various accrued liabilities	163	274
Goodwill	12,885	25,739
U.S. tax net operating loss carry forwards	53,617	59,258
State tax net operating loss carry forwards	8,201	6,148
Foreign tax net operating loss carry forwards	2,817	2,817
Alternative Minimum Tax credit carryforward	0	846
Other	211	117
Gross deferred tax assets	86,248	105,827
Valuation allowance	(68,003)	(69,304)
Deferred tax assets, net of valuation allowance	18,245	36,523
Non-current:
Term Loan amortization	(394)	(1,203)
Depreciation	(3,150)	(7,409)
Intangible amortization	(14,701)	(27,596)
Deferred tax liabilities	(18,245)	(36,208)
United States	0	0
Foreign	0	315
Net deferred tax assets	$ 0	$ 315

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications	$ 1,287	$ 553	$ (11,756)
Amounts reclassified from accumulated other comprehensive income (loss)	1,085	1,222	2,959
Net current-period other comprehensive income	2,372	1,775	(8,797)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(4,234)	(6,009)	2,788
Balance, end of period	(1,862)	(4,234)	(6,009)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(1,412)	(1,965)	6,863
Other comprehensive income before reclassifications	1,287	553	(8,828)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Net current-period other comprehensive income	1,287	553	(8,828)
Balance, end of period	(125)	(1,412)	(1,965)
Changes in derivative financial instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(2,822)	(4,044)	(4,075)
Other comprehensive income before reclassifications	0	0	(2,928)
Amounts reclassified from accumulated other comprehensive income (loss)	1,085	1,222	2,959
Net current-period other comprehensive income	1,085	1,222	31
Balance, end of period	$ (1,737)	$ (2,822)	$ (4,044)

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Detail) - Amount Reclassified from Accumulated Other Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Total	$ 1,085	$ 1,222	$ 2,959
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate contracts	$ 1,085	$ 1,222	$ 2,959

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 2.9	$ 4.1	$ 8.6
Fair value of RSU's vested	3.3	5.9	9.8
Unrecognized compensation cost, net of estimated forfeitures, related to all non-vested share-based compensation arrangements	$ 3.6
Expected recognized cost over a weighted-average period	2 years 3 months 18 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted period under the options plan	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted period under the options plan	4 years
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 0.4	$ 0.5	$ 2.3
Director Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted period under the options plan	1 year
2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	4,960,315

Stockholders' Equity - RSU Acti

Stockholders' Equity - RSU Activity and Related Information (Detail) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding balance, Shares | shares	1,219,446
Granted, Shares | shares	711,990
Vested, Shares | shares	(809,652)
Forfeited, Shares | shares	(108,137)
Outstanding balance, Shares | shares	1,013,647
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding balance, Weighted-Average Grant-Date Fair Value (in USD per share) | $ / shares	$ 3.87
Granted, Weighted-Average Grant-Date Fair Value (in USD per share) | $ / shares	2.47
Vested, Weighted-Average Grant-Date Fair Value (in USD per share) | $ / shares	4.10
Forfeited, Weighted-Average Grant-Date Fair Value (in USD per share) | $ / shares	2.62
Outstanding balance, Weighted-Average Grant-Date Fair Value (in USD per share) | $ / shares	$ 2.84

Stockholders' Equity - Fair Val

Stockholders' Equity - Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	99.80%	91.10%	77.80%
Risk-free interest rates	1.37%	1.01%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rates		0.49%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rates		0.96%

Income (Loss) Per Common Shar79

Income (Loss) Per Common Share - Schedule of Basic and Diluted Income (Loss) Per Common Share from Continuing Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net loss from continuing operations applicable to common shares (numerator for basic and diluted calculation)	$ (55,093)	$ (32,709)	$ (1,121)	$ (17,736)	$ (14,062)	$ (5,761)	$ (13,298)	$ (10,661)	$ (106,659)	$ (43,782)	$ (64,549)
Weighted average number of common shares outstanding for basic income per share (in shares)	62,329,614	62,310,191	62,170,910	61,829,768	61,682,996	61,299,334	60,756,314	61,639,590	62,160,849	61,364,592	57,759,988
Weighted average number of potentially dilutive common shares outstanding (in shares)									0	0	0
Weighted average number of common shares outstanding for diluted income per share (in shares)	62,329,614	62,310,191	62,170,910	61,829,768	61,682,996	61,299,334	60,756,314	61,639,590	62,160,849	61,364,592	57,759,988
Loss per common share from continuing operations:
Basic (in dollar per share)	$ (0.89)	$ (0.52)	$ (0.02)	$ (0.29)	$ (0.23)	$ (0.09)	$ (0.22)	$ (0.17)	$ (1.72)	$ (0.71)	$ (1.12)
Diluted (in dollar per share)	$ (0.89)	$ (0.52)	$ (0.02)	$ (0.29)	$ (0.23)	$ (0.09)	$ (0.22)	$ (0.17)	$ (1.72)	$ (0.71)	$ (1.12)

Income (Loss) Per Common Shar80

Income (Loss) Per Common Share - Schedule of Potentially Dilutive Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from the computation of diluted income (loss) per share (shares)	274,210	551,924	720,955
Restricted stock and restricted stock rights
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from the computation of diluted income (loss) per share (shares)	274,210	519,137	665,955
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from the computation of diluted income (loss) per share (shares)	0	32,787	55,000

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017ProjectSegment
Segment Reporting [Abstract]
Number of reportable segments | Segment	3
Number of Projects | Project	1
Customers representing percent	10.00%

Segment Information - Schedule

Segment Information - Schedule of Company's Operations by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Contract revenue	$ 217,863	$ 240,773	$ 227,447	$ 163,900	$ 164,392	$ 193,442	$ 199,030	$ 174,821	$ 849,983	$ 731,685	$ 908,994
Contract costs									874,738	685,389	868,240
Contract income (loss)									(24,755)	46,296	40,754
Amortization of intangibles									9,667	9,754	9,874
General and administrative									54,693	60,993	77,335
Gain on sale of subsidiary									0	0	(12,826)
Other charges									2,226	6,210	18,469
Operating loss	(49,057)	(27,789)	358	(14,853)	(12,140)	(2,741)	(9,461)	(6,319)	(91,341)	(30,661)	(52,098)
Non-operating expenses									(16,282)	(13,651)	(66,482)
Benefit for income taxes									(964)	(530)	(54,031)
Loss from continuing operations	(55,093)	(32,709)	(1,121)	(17,736)	(14,062)	(5,761)	(13,298)	(10,661)	(106,659)	(43,782)	(64,549)
Income (loss) from discontinued operations, net of provision for income taxes	72	(1,496)	19	(31)	(141)	(658)	(1,853)	(1,325)	(1,436)	(3,977)	96,032
Net income (loss)	(55,021)	$ (34,205)	$ (1,102)	$ (17,767)	(14,203)	$ (6,419)	$ (15,151)	$ (11,986)	(108,095)	(47,759)	31,483
Depreciation and amortization									19,162	21,919	27,200
Capital expenditures by segment									2,561	3,802	2,183
Total assets, continuing operations	363,553				362,531				363,553	362,531
Operating segments | Utility T&D
Segment Reporting Information [Line Items]
Contract revenue									506,978	418,387	379,629
Contract costs									486,340	378,229	354,267
Contract income (loss)									20,638	40,158	25,362
Amortization of intangibles									9,559	9,559	9,559
General and administrative									16,360	15,035	9,841
Gain on sale of subsidiary											0
Other charges									0	(3)	2,002
Operating loss									(5,281)	15,567	3,960
Depreciation and amortization									15,300	16,511	18,719
Capital expenditures by segment									1,953	2,493	451
Total assets, continuing operations	196,923				201,339				196,923	201,339
Operating segments | Canada
Segment Reporting Information [Line Items]
Contract revenue									121,151	143,140	232,534
Contract costs									115,870	134,248	209,439
Contract income (loss)									5,281	8,892	23,095
Amortization of intangibles									0	0	0
General and administrative									7,659	8,538	12,245
Gain on sale of subsidiary											0
Other charges									1,667	1,004	624
Operating loss									(4,045)	(650)	10,226
Depreciation and amortization									737	924	1,321
Capital expenditures by segment									271	693	519
Total assets, continuing operations	41,958				47,704				41,958	47,704
Operating segments | Oil & Gas
Segment Reporting Information [Line Items]
Contract revenue									221,939	170,448	297,110
Contract costs									272,613	173,202	304,813
Contract income (loss)									(50,674)	(2,754)	(7,703)
Amortization of intangibles									108	195	315
General and administrative									9,584	12,175	20,154
Gain on sale of subsidiary											0
Other charges									139	1,659	9,852
Operating loss									(60,505)	(16,783)	(38,024)
Depreciation and amortization									2,041	3,142	5,241
Capital expenditures by segment									275	323	605
Total assets, continuing operations	50,779				42,887				50,779	42,887
Corporate
Segment Reporting Information [Line Items]
Contract revenue									0	0	0
Contract costs									0	0	0
Contract income (loss)									0	0	0
Amortization of intangibles									0	0	0
General and administrative									21,090	25,245	35,095
Gain on sale of subsidiary											0
Other charges									420	3,550	5,991
Operating loss									(21,510)	(28,795)	(41,086)
Depreciation and amortization									1,084	1,342	1,919
Capital expenditures by segment									62	293	608
Total assets, continuing operations	$ 73,893				$ 70,601				73,893	70,601
Eliminations
Segment Reporting Information [Line Items]
Contract revenue									(85)	(290)	(279)
Contract costs									(85)	(290)	(279)
Contract income (loss)									0	0	0
Amortization of intangibles									0	0	0
General and administrative									0	0	0
Gain on sale of subsidiary											0
Other charges									0	0	0
Operating loss									$ 0	$ 0	$ 0

Segment Information - Total Con

Segment Information - Total Contract Revenue (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Oncor
Revenues from External Customers and Long-Lived Assets [Line Items]
Total contract revenue	25.00%	25.00%	17.90%
Enterprise Products Partners L.P.
Revenues from External Customers and Long-Lived Assets [Line Items]
Total contract revenue	9.80%	9.40%	12.50%

Segment Information - Informati

Segment Information - Information about the Company's Operations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Contract revenue:
Contract revenue	$ 217,863	$ 240,773	$ 227,447	$ 163,900	$ 164,392	$ 193,442	$ 199,030	$ 174,821	$ 849,983	$ 731,685	$ 908,994
Property, plant and equipment, net:
Property, plant and equipment, net	30,113				38,123				30,113	38,123
United States
Contract revenue:
Contract revenue									728,832	588,545	676,460
Property, plant and equipment, net:
Property, plant and equipment, net	25,804				33,625				25,804	33,625
Canada
Contract revenue:
Contract revenue									121,151	143,140	$ 232,534
Property, plant and equipment, net:
Property, plant and equipment, net	$ 4,309				$ 4,498				$ 4,309	$ 4,498

Contingencies, Commitments an85

Contingencies, Commitments and Other Circumstances - Contingencies (Details)	Jan. 31, 2015Plaintiff	Mar. 04, 2015Complaint
In re Willbros Group, Inc. Securities Litigation
Loss Contingencies [Line Items]
Number of plaintiffs | Plaintiff	2
Markovich v Harl et al And Kumararatne v. McNabb et al
Loss Contingencies [Line Items]
Number of complaints filed | Complaint		2

Contingencies, Commitments an86

Contingencies, Commitments and Other Circumstances - Commitments and Other (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitment And Contingencies [Line Items]
Face value of primarily performance bonds	$ 155.3
Liability recognized for letters of credit	0
Rental expense for continuing operations	16.3	$ 23.3	$ 33
Operating lease payable, future minimum due	90.4
Operating lease payable, 2018	25.1
Operating lease payable, 2019	19.3
Operating lease payable, 2020	14.1
Operating lease payable, 2021	12.1
Operating lease payable, 2022	6.9
Operating lease payable, thereafter	12.9
Continuing Operations
Commitment And Contingencies [Line Items]
Outstanding letters of credit, continuing operations	$ 49.1

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payments on term loan facility				$ 0	$ 3,128,000	$ 174,648,000
Fair value of swap agreement reclassified from OCI to interest expense				16,017,000	13,976,000	$ 27,254,000
Recognized interest expense for next twelve months				1,100,000
2014 Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payments on term loan facility	$ 3,100,000	$ 93,600,000
Changes in derivative financial instruments | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of swap agreement reclassified from OCI to interest expense	$ 100,000	$ 1,200,000
Designated as Hedging Instrument | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount of derivatives							$ 124,100,000
Variable rate interest expense							$ 124,100,000
Termination of swap agreement recorded in AOCI as fair value			$ 5,700,000
Net Investment Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount of derivatives				$ 0	$ 0

Fair Value Measurements - Deriv

Fair Value Measurements - Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Gain Recognized in OCI on Derivative (Effective Portion)	$ 0	$ 0	$ (2,928)
Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion)	1,085	1,222	2,959
Interest expense, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion)	1,085	1,222	2,959
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Gain Recognized in OCI on Derivative (Effective Portion)	$ 0	$ 0	$ (2,928)

Other Charges (Narrative) (Deta

Other Charges (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Costs recognized	$ 2,226	$ 6,210	$ 18,469
Write-off of deferred rent	0	800	1,800
Gain (loss) on sale of equipment		(700)	(1,200)
Gain (loss) on sale of assets			(2,200)
Oil & Gas | Fabrication Services
Restructuring Cost and Reserve [Line Items]
Gain (loss) on sale of assets		(300)
Impairment of PP&E held for sale			2,000
Utility T&D
Restructuring Cost and Reserve [Line Items]
Impairment of PP&E held for sale			1,300
Equipment and facility lease abandonment
Restructuring Cost and Reserve [Line Items]
Costs recognized	(225)	3,633	7,747
Adjustment to decrease lease abandonment liabilities	800
Loss on disposal of equipment
Restructuring Cost and Reserve [Line Items]
Costs recognized	0	1,030	6,683
Employee severance charges
Restructuring Cost and Reserve [Line Items]
Costs recognized	1,564	1,300	1,728
Restatement costs
Restructuring Cost and Reserve [Line Items]
Costs recognized	636	(24)	595
Impairment of intangible assets
Restructuring Cost and Reserve [Line Items]
Costs recognized	0	0	534
Accelerated stock vesting
Restructuring Cost and Reserve [Line Items]
Costs recognized	$ 251	$ 271	$ 1,182

Other Charges - Restructuring R

Other Charges - Restructuring Reserve (Details) - Equipment and facility lease abandonment $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Restructuring Reserve [Roll Forward]
Accrued cost at December 31, 2016	$ 5,479
Cash payments	(1,719)
Non-cash charges	340
Change in estimates	(225)
Accrued cost at December 31, 2017	3,875
Operating segments | Utility T&D
Restructuring Reserve [Roll Forward]
Accrued cost at December 31, 2016	348
Cash payments	(176)
Non-cash charges	0
Change in estimates	0
Accrued cost at December 31, 2017	172
Operating segments | Canada
Restructuring Reserve [Roll Forward]
Accrued cost at December 31, 2016	290
Cash payments	(120)
Non-cash charges	0
Change in estimates	41
Accrued cost at December 31, 2017	211
Operating segments | Oil & Gas
Restructuring Reserve [Roll Forward]
Accrued cost at December 31, 2016	793
Cash payments	(296)
Non-cash charges	0
Change in estimates	48
Accrued cost at December 31, 2017	545
Corporate
Restructuring Reserve [Roll Forward]
Accrued cost at December 31, 2016	4,048
Cash payments	(1,127)
Non-cash charges	340
Change in estimates	(314)
Accrued cost at December 31, 2017	$ 2,947

Discontinued Operations - Addit

Discontinued Operations - Additional Information (Detail) $ in Millions	Mar. 31, 2015USD ($)	Mar. 17, 2015USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)Business	Nov. 30, 2015USD ($)	Jun. 12, 2015USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of businesses disposed | Business									3
Discontinued Operations, Disposed of by Sale | Professional Services
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration for sale of equity interest										$ 130
Holdback amount										$ 7.5
Gain (loss) on sale of business									$ 97
Escrow amount received				$ 2.2		$ 2.4		$ 4.6
Adjustment to prior period gain (loss) on disposal					$ (1)	$ (1.5)		(2.5)
Discontinued Operations, Disposed of by Sale | Downstream Professional Services
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration for sale of equity interest											$ 10
Gain (loss) on sale of business								(2.2)
Discontinued Operations, Disposed of by Sale | Premier Utility Services, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration for sale of equity interest	$ 51
Gain (loss) on sale of business									37.1
Escrow amount received			$ 1.7		$ 2			$ 3.7
Escrow deposit	$ 4
Escrow deposit period	18 months
Discontinued Operations, Disposed of by Sale | UtilX
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration for sale of equity interest		$ 40
Gain (loss) on sale of business									$ 20.3
Escrow deposit		$ 0.5
Escrow deposit period		6 months
Decrease in escrow account							$ (0.5)

Discontinued Operations - Held

Discontinued Operations - Held for Sale Operations and Asset Disposals - Schedule of Major Classes of Revenue And Income (Losses) With Respect to the Discontinued Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets with respect to discontinued operations
Accounts receivable, net	$ 490	$ 7,806
Total assets	1,804	9,050
Contract billings in excess of costs	765	4,480
Total liabilities	865	8,275
Discontinued Operations, Disposed of by Sale
Revenues from External Customers and Long-Lived Assets [Line Items]
Contract revenue	1,006	2,126	$ 231,560
Contract costs	831	2,299	198,731
Amortization of intangibles			793
Loss (gain) on sale of subsidiaries		2,456	(152,208)
General and administrative	1,022	2,320	26,567
Other charges	525		4,405
Other income		(1,060)
Operating income (loss)	(1,372)	(3,889)	153,272
Non-operating income (expense)	0	0	(30)
Pre-tax income (loss)	(1,372)	(3,889)	153,242
Provision for income taxes	64	88	57,210
Net income (loss)	(1,436)	(3,977)	96,032
Assets with respect to discontinued operations
Accounts receivable, net		313
Contract cost and recognized income not yet billed	324	192
Total assets	324	505
Accounts payable and accrued liabilities	517	689
Contract billings in excess of costs		358
Other current liabilities	574	531
Other long-term liabilities	893	995
Total liabilities	1,984	2,573
Net liabilities associated with discontinued operations	(1,660)	(2,068)
Discontinued Operations, Disposed of by Sale | Professional Services
Revenues from External Customers and Long-Lived Assets [Line Items]
Contract revenue	1,006	2,126	229,482
Contract costs	831	2,299	197,414
Amortization of intangibles			793
Loss (gain) on sale of subsidiaries		2,456	(152,208)
General and administrative	1,219	2,633	26,937
Other charges	525		4,405
Other income		(1,060)
Operating income (loss)	(1,569)	(4,202)	152,141
Non-operating income (expense)	0	0	(36)
Pre-tax income (loss)	(1,569)	(4,202)	152,105
Provision for income taxes	64	0	57,210
Net income (loss)	(1,633)	(4,202)	94,895
Assets with respect to discontinued operations
Accounts receivable, net		313
Contract cost and recognized income not yet billed	324	192
Total assets	324	505
Accounts payable and accrued liabilities	337	412
Contract billings in excess of costs		358
Other current liabilities	574	531
Other long-term liabilities	893	995
Total liabilities	1,804	2,296
Net liabilities associated with discontinued operations	(1,480)	(1,791)
Discontinued Operations, Disposed of by Sale | Hawkeye
Revenues from External Customers and Long-Lived Assets [Line Items]
Contract revenue	0	0	2,078
Contract costs	0	0	1,317
Amortization of intangibles			0
Loss (gain) on sale of subsidiaries		0	0
General and administrative	(197)	(313)	(370)
Other charges	0		0
Other income		0
Operating income (loss)	197	313	1,131
Non-operating income (expense)	0	0	6
Pre-tax income (loss)	197	313	1,137
Provision for income taxes	0	0	0
Net income (loss)	197	313	1,137
Assets with respect to discontinued operations
Accounts receivable, net		0
Contract cost and recognized income not yet billed	0	0
Total assets	0	0
Accounts payable and accrued liabilities	180	277
Contract billings in excess of costs		0
Other current liabilities	0	0
Other long-term liabilities	0	0
Total liabilities	180	277
Net liabilities associated with discontinued operations	(180)	(277)
Discontinued Operations, Disposed of by Sale | Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Contract revenue	0	0	0
Contract costs	0	0	0
Amortization of intangibles			0
Loss (gain) on sale of subsidiaries		0	0
General and administrative	0	0	0
Other charges	0		0
Other income		0
Operating income (loss)	0	0	0
Non-operating income (expense)	0	0	0
Pre-tax income (loss)	0	0	0
Provision for income taxes	0	88	0
Net income (loss)	$ 0	$ (88)	$ 0

Quarterly Financial Data (Una93

Quarterly Financial Data (Unaudited) - Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Contract revenue	$ 217,863	$ 240,773	$ 227,447	$ 163,900	$ 164,392	$ 193,442	$ 199,030	$ 174,821	$ 849,983	$ 731,685	$ 908,994
Contract income	(31,327)	(12,188)	17,079	1,681	5,325	15,157	13,799	12,015	(24,755)	46,296
Operating income (loss)	(49,057)	(27,789)	358	(14,853)	(12,140)	(2,741)	(9,461)	(6,319)	(91,341)	(30,661)	(52,098)
Income (loss) from continuing operations before income taxes	(54,392)	(31,577)	(3,318)	(18,336)	(15,738)	(5,574)	(13,131)	(9,869)	(107,623)	(44,312)	(118,580)
Loss from continuing operations	(55,093)	(32,709)	(1,121)	(17,736)	(14,062)	(5,761)	(13,298)	(10,661)	(106,659)	(43,782)	(64,549)
Income (loss) from discontinued operations, net of provision for income taxes	72	(1,496)	19	(31)	(141)	(658)	(1,853)	(1,325)	(1,436)	(3,977)	96,032
Net income (loss)	$ (55,021)	$ (34,205)	$ (1,102)	$ (17,767)	$ (14,203)	$ (6,419)	$ (15,151)	$ (11,986)	$ (108,095)	$ (47,759)	$ 31,483
Basic income (loss) per share attributable to Company shareholders:
Loss from continuing operations (in dollar per share)	$ (0.89)	$ (0.52)	$ (0.02)	$ (0.29)	$ (0.23)	$ (0.09)	$ (0.22)	$ (0.17)	$ (1.72)	$ (0.71)	$ (1.12)
Loss from discontinued operations (in dollar per share)	0	(0.02)	0	0	0	(0.01)	(0.03)	(0.02)	(0.02)	(0.06)	1.66
Net income (loss) (in dollar per share)	(0.89)	(0.54)	(0.02)	(0.29)	(0.23)	(0.10)	(0.25)	(0.19)	(1.74)	(0.77)	0.54
Diluted income (loss) per share attributable to Company shareholders:
Loss from continuing operations (in dollar per share)	(0.89)	(0.52)	(0.02)	(0.29)	(0.23)	(0.09)	(0.22)	(0.17)	(1.72)	(0.71)	(1.12)
Loss from discontinued operations (in dollar per share)	0	(0.02)	0	0	0	(0.01)	(0.03)	(0.02)	(0.02)	(0.06)	1.66
Net income (loss) (in dollar per share)	$ (0.89)	$ (0.54)	$ (0.02)	$ (0.29)	$ (0.23)	$ (0.10)	$ (0.25)	$ (0.19)	$ (1.74)	$ (0.77)	$ 0.54
Weighted average number of common shares outstanding
Basic (in shares)	62,329,614	62,310,191	62,170,910	61,829,768	61,682,996	61,299,334	60,756,314	61,639,590	62,160,849	61,364,592	57,759,988
Diluted (in shares)	62,329,614	62,310,191	62,170,910	61,829,768	61,682,996	61,299,334	60,756,314	61,639,590	62,160,849	61,364,592	57,759,988

Quarterly Financial Data (Una94

Quarterly Financial Data (Unaudited) - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Line Items]
Payments on term loan facility							$ 0	$ 3,128	$ 174,648
2014 Term Loan
Quarterly Financial Data [Line Items]
Payments on term loan facility					$ 3,100	$ 93,600
Debt extinguishment costs	$ 33,500
Professional Services | Discontinued Operations, Disposed of by Sale
Quarterly Financial Data [Line Items]
Escrow amount received			$ 2,200		2,400			4,600
Adjustment to prior period gain (loss) on disposal				$ (1,000)	$ (1,500)			(2,500)
Premier Utility Services, LLC | Discontinued Operations, Disposed of by Sale
Quarterly Financial Data [Line Items]
Escrow amount received		$ 1,700		$ 2,000				3,700
Bemis | Discontinued Operations, Disposed of by Sale
Quarterly Financial Data [Line Items]
Escrow amount received			$ 900
JP Morgan Chase Bank NA and KKR Credit Advisors (US) LLC | 2014 Term Loan
Quarterly Financial Data [Line Items]
Payments on term loan facility							0	3,100
Debt extinguishment costs							$ 0	$ 100

SCHEDULE II - CONSOLIDATED VA95

SCHEDULE II - CONSOLIDATED VALUATION AND QUALIFYING ACCOUNTS Schedule II - Consolidated Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Bad Debts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 1,963	$ 4,482	$ 2,723
Charged (Credited) to Costs and Expense	887	284	2,945
Charge Offs and Other	(54)	(2,803)	(1,186)
Balance at End of Year	2,796	1,963	4,482
Deferred Tax Valuation Allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	69,304	58,435	80,794
Charged (Credited) to Costs and Expense		10,869	(22,359)
Balance at End of Year	$ 68,003	$ 69,304	$ 58,435