Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 7,753	$ (3,949)
Adjustments to reconcile to net cash used in operating activities:
Depreciation and amortization	11,852	11,376
Gain on sale of fixed assets	(116)	(499)
Equity-based compensation expense	3,096	2,363
Deferred income taxes	5,533	(1,187)
Non-cash restructuring charges	42	(212)
Loss on foreign currency transactions	378	1,131
Other	(62)	(485)
Changes in operating assets and liabilities (net of acquisitions):
Restricted cash related to operating activities	1,354	462
Receivables net, retainage and costs and estimated earnings in excess of billings	(30,257)	29,618
Inventories	(3,491)	(1,806)
Prepaid expenses and other assets	5,351	3,382
Accounts payable and accrued expenses	(9,988)	(39,086)
Billings in excess of costs and estimated earnings	(18,078)	(3,672)
Other operating	300	582
Net cash used in operating activities	(26,333)	(1,982)
Cash flows from investing activities:
Capital expenditures	(3,907)	(10,060)
Proceeds from sale of fixed assets	165	956
Patent expenditures	(289)	(541)
Restricted cash related to investing activities	2,000	(1,086)
Purchase of Underground Solutions, Inc., net of cash acquired	0	(85,167)
Other acquisition activity, net of cash acquired	(9,045)	(500)
Sale of interest in Bayou Perma-Pipe Canada, Ltd., net of cash disposed	0	4,599
Net cash used in investing activities	(11,076)	(91,799)
Cash flows from financing activities:
Proceeds from issuance of common stock upon stock option exercises	0	38
Repurchase of common stock	(10,508)	(16,325)
Payment of contingent consideration	500	0
Proceeds from line of credit	10,000	34,000
Principal payments on long-term debt	(4,375)	(4,375)
Net cash provided by (used in) financing activities	(5,383)	13,338
Effect of exchange rate changes on cash	894	(3,394)
Net decrease in cash and cash equivalents for the period	(41,898)	(83,837)
Cash and cash equivalents, beginning of period	129,500	211,696
Cash and cash equivalents, end of period	$ 87,602	$ 127,859