Assets and Liabilities Held for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Assets held for sale:
Cash and cash equivalents	$ 813	$ 1,000	$ 0
Total current assets	72,683	70,314
Liabilities held for sale:
Total current liabilities	14,731	20,900
Bayou | Disposal Group, Held-for-sale, Not Discontinued Operations
Assets held for sale:
Cash and cash equivalents	813	989
Receivables, net	8,143	6,368
Contract assets	1,371	1,299
Inventories	3,541	3,727
Prepaid expenses and other current assets	763	827
Total current assets	14,631	13,210
Property, plant & equipment, less accumulated depreciation	54,835	53,887
Identified intangible assets, less accumulated amortization	3,217	3,217
Total assets held for sale	72,683	70,314
Liabilities held for sale:
Accounts payable	2,249	5,763
Accrued expenses	1,543	1,805
Contract liabilities	3,076	5,478
Total current liabilities	6,868	13,046
Long-term debt	7,757	7,757
Other non-current liabilities	106	97
Total liabilities held for sale	$ 14,731	$ 20,900