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)	$ 400	$ (3,620)	$ (8,060)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization	29,491	34,162	28,083
Deferred financing cost amortization	1,269	1,225	462
Bad debt expense	0	0	22
Deferred income taxes	(4,166)	751	(2,885)
Stock-based compensation	2,303	2,280	2,275
(Gain) loss on sale of property and equipment	(674)	(1,579)	466
Change in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	15,022	(23,935)	(2,666)
Income tax receivable	(952)	(49)	249
Inventory	89	1,696	1,150
Accounts receivable, non-current	0	(511)	(222)
Prepaid expenses and other	(226)	856	(467)
Costs and estimated earnings in excess of billings on uncompleted contracts	(6,030)	19,640	(10,655)
Accounts payable	(5,666)	(5,717)	12,245
Accrued liabilities	(1,519)	(1,123)	1,658
Income tax payable	(433)	(125)	(1,097)
Billings in excess of costs and estimated earnings on uncompleted contracts	5,225	(802)	4,655
Deferred revenue	0	0	(34)
Net cash provided by operating activities	34,133	23,149	25,179
Cash flows from investing activities:
Proceeds from sale of property and equipment	6,826	2,152	2,708
Purchase of property and equipment	(10,729)	(18,715)	(20,802)
TBC acquisition adjustment	(557)	0	0
Insurance proceeds for PPE	925	0	0
Net cash used in investing activities	(10,080)	(17,686)	(128,795)
Cash flows from financing activities:
Borrowings from Credit Facility	72,000	57,000	149,021
Payments made on borrowings from Credit Facility	(87,813)	(63,084)	(42,955)
Extinguishment of debt	0	0	(32,427)
Loan costs from Credit Facility	(779)	(486)	(4,498)
Exercise of stock options	1,320	67	28
Purchase of shares into treasury	0	0	(3,101)
Net cash (used in) provided by financing activities	(15,272)	(6,503)	66,068
Net change in cash and cash equivalents	8,781	(1,040)	(37,548)
Cash and cash equivalents at beginning of year	305	1,345	38,893
Cash and cash equivalents at end of year	9,086	305	1,345
Supplemental disclosures of cash flow information, cash paid during the period for:
Interest	4,413	5,031	3,063
Taxes, net of refunds	1,008	999	584
Acquisition of TAS and purchase price adjustment
Cash flows from investing activities:
Payments for acquisition of businesses	0	(369)	(110,344)
Houston Industrial Tool Services, Inc.
Cash flows from investing activities:
Payments for acquisition of businesses	0	0	(357)
Acquisition of business in Pacific Northwest
Cash flows from investing activities:
Payments for acquisition of businesses	(6,000)	0	0
Acquisition of TW LaQuay Dredging [Member]
Cash flows from investing activities:
Payments for acquisition of businesses	$ (545)	$ (754)	$ 0