Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ 29,160	$ (7,990)	$ (35,412)
Loss from discontinued operations	0	0	3,847
Income (loss) from continuing operations	29,160	(7,990)	(31,565)
Adjustments to reconcile to net cash provided by operating activities:
Depreciation and amortization	46,719	43,791	44,312
Gain on sale of fixed assets	(1,916)	(929)	(310)
Equity-based compensation expense	9,261	7,987	5,073
Deferred income taxes	1,772	924	(16,816)
Equity in earnings of affiliated companies	0	0	(570)
Non-cash restructuring charges	300	1,816	20,592
Non-cash portion of litigation settlement	(3,000)	0	0
Fixed asset impairment	0	0	11,870
Definite-lived intangible asset impairment	0	0	12,116
Goodwill impairment	0	43,484	51,512
Debt issuance costs	0	3,377	157
Loss on sale of businesses	0	3,414	988
Loss on foreign currency transactions	911	80	627
Other	(1,044)	(168)	1,279
Changes in operating assets and liabilities (net of acquisitions):
Restricted cash related to operating activities	2,055	(382)	(454)
Return on equity of affiliated companies	0	0	590
Receivables net, retainage and costs and estimated earnings in excess of billings	52,774	12,283	(41,211)
Inventories	(2,569)	6,984	(5,286)
Prepaid expenses and other assets	16,759	(28,895)	3,465
Accounts payable and accrued expenses	(49,259)	(582)	5,997
Billings in excess of costs and estimated earnings	(27,761)	45,700	19,100
Other operating	(946)	1,129	402
Net cash provided by operating activities of continuing operations	73,216	132,023	81,868
Net cash used in operating activities of discontinued operations	0	0	(1,045)
Net cash provided by operating activities	73,216	132,023	80,823
Cash flows from investing activities:
Capital expenditures	(38,760)	(29,454)	(32,899)
Proceeds from sale of fixed assets	3,310	3,173	1,547
Patent expenditures	(1,043)	(1,503)	(1,923)
Restricted cash related to investing activities	(1,086)	(3,538)	(1,153)
Purchase of Underground Solutions, Inc., net of cash acquired	(84,740)	0	0
Purchase of Fyfe Europe S.A. and related companies	(2,800)	0	0
Purchase of CIPP business of Leif M. Jensen A/S	(3,235)	0	0
Purchase of Concrete Solutions Limited and Building Chemical Supplies Limited	(5,532)	0	0
Purchase of Schultz Mechanical Contractors, Inc.	0	(6,662)	0
Sale of interest in Bayou Perma-Pipe Canada, Ltd., net of cash disposed	6,599	0	0
Sale of interests in Bayou Coating, L.L.C.	0	0	9,065
Sale of Ka-te Insituform AG	0	0	1,123
Payment to Fyfe Asia sellers for final net working capital	0	(1,098)	0
Payment from Brinderson sellers for final net working capital	0	0	(1,000)
Net cash used in investing activities of continuing operations	(127,287)	(39,082)	(23,240)
Net cash provided by investing activities of discontinued operations	0	0	1,045
Net cash used in investing activities	(127,287)	(39,082)	(22,195)
Cash flows from financing activities:
Proceeds from issuance of common stock upon stock option exercises, including tax effects	1,818	2,466	8,615
Repurchase of common stock	(44,454)	(27,804)	(31,085)
Sale of non-controlling interest	0	239	0
Purchase of or distributions to non-controlling interests	(1,276)	(472)	(617)
Payment of contingent consideration	(500)	(684)	0
Credit facility financing fees	0	(4,360)	(783)
Proceeds from notes payable	0	1,505	1,284
Principal payments on notes payable	0	(1,875)	0
Proceeds from line of credit	42,000	26,000	18,000
Payments on line of credit	(6,000)	(71,500)	(8,000)
Proceeds from long-term debt	0	350,000	0
Principal payments on long-term debt	(17,500)	(323,750)	(22,039)
Net cash used in financing activities	(25,912)	(50,235)	(34,625)
Effect of exchange rate changes on cash	(2,213)	(5,975)	(7,083)
Net increase (decrease) in cash and cash equivalents for the year	(82,196)	36,731	16,920
Cash and cash equivalents, beginning of year	211,696	174,965	158,045
Cash and cash equivalents, end of year	129,500	211,696	174,965
Cash and cash equivalents associated with assets held for sale, end of year	0	(2,443)	0
Cash and cash equivalents from continuing operations, end of year	129,500	209,253	174,965
Supplemental disclosures of cash flow information:
Interest	11,118	9,873	9,602
Income taxes	$ (517)	$ 8,753	$ 12,594