Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 3,087	$ (66,582)	$ 29,125
Adjustments to reconcile to net cash provided by operating activities:
Depreciation and amortization	37,855	44,419	46,719
(Gain) loss on sale of fixed assets	143	(59)	(1,916)
Equity-based compensation expense	7,838	10,060	10,059
Deferred income taxes	(648)	(9,376)	1,772
Non-cash restructuring charges	13,814	10,080	300
Non-cash portion of litigation settlement	0	0	3,000
Goodwill impairment	1,389	45,390	0
Definite-lived intangible asset impairment	2,169	41,032	0
Loss on sale of businesses	7,048	0	0
Loss on foreign currency transactions	623	2,152	911
Other	1,278	(1,562)	(1,044)
Changes in operating assets and liabilities (net of acquisitions):
Receivables net, retainage and contract assets	(6,821)	(29,847)	52,774
Inventories	2,306	(1,926)	(2,569)
Prepaid expenses and other assets	614	8,732	16,759
Accounts payable and accrued expenses	(7,339)	18,803	(50,022)
Contract liabilities	(24,144)	(5,924)	(27,761)
Other operating	457	(1,798)	(946)
Net cash provided by operating activities	39,669	63,594	71,161
Cash flows from investing activities:
Capital expenditures	(30,514)	(30,830)	(38,760)
Proceeds from sale of fixed assets	3,036	707	3,310
Patent expenditures	(299)	(379)	(1,043)
Purchase of Underground Solutions, Inc., net of cash acquired	0	0	(84,740)
Other acquisition activity, net of cash acquired	(9,000)	(9,045)	(11,567)
Sale of Bayou, net of cash disposed	37,942	0	0
Sale of interest in Bayou Perma-Pipe Canada, Ltd., net of cash disposed	0	0	(6,599)
Net cash provided by (used in) investing activities	1,165	(39,547)	(126,201)
Cash flows from financing activities:
Proceeds from issuance of common stock upon stock option exercises, including tax effects	0	823	1,818
Repurchase of common stock	(25,775)	(37,849)	(44,454)
Investments from non-controlling interest	0	158	0
Purchase of or distributions to non-controlling interests	0	(71)	(1,276)
Payment of contingent consideration	0	(500)	(500)
Credit facility amendment fees	(1,657)	0	0
Proceeds from notes payable, net	234	639	0
Proceeds from (payments on) line of credit, net	(7,000)	2,000	36,000
Principal payments on long-term debt	(26,250)	(21,647)	(17,500)
Net cash used in financing activities	(60,448)	(56,447)	(25,912)
Effect of exchange rate changes on cash	(4,045)	6,553	(2,148)
Net decrease in cash, cash equivalents and restricted cash for the year	(23,659)	(25,847)	(83,100)
Cash, cash equivalents and restricted cash, beginning of year	108,545	134,392	217,492
Cash, cash equivalents and restricted cash, end of year	84,886	108,545	134,392
Cash, cash equivalents and restricted cash, assets held for sale, end of year	0	989	0
Cash, cash equivalents and restricted cash	84,886	107,556	134,392
Supplemental disclosures of cash flow information:
Interest	15,622	14,998	11,118
Income taxes	$ 4,625	$ 5,649	$ (517)