Business Segment Information - Property and Equipment Additions, Depreciation and Amortization and Identifiable Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Property and equipment additions	$ 5,461	$ 763	$ 1,151
Depreciation and amortization	18,903	16,520	11,268
Identifiable Assets	498,634	598,819
Environmental Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	404	166	486
Depreciation and amortization	3,816	4,443	2,263
Identifiable Assets	118,680	135,171
Energy Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	569	429	136
Depreciation and amortization	9,555	5,293	2,329
Identifiable Assets	257,566	283,002
Fluid Handling and Filtration Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	4,481	150	486
Depreciation and amortization	5,406	6,331	6,545
Identifiable Assets	104,294	161,394
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	7	18	43
Depreciation and amortization	126	453	$ 131
Identifiable Assets	$ 18,094	$ 19,252