Business Segment Information - Property and Equipment Additions, Depreciation and Amortization and Identifiable Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property and equipment additions	$ 231	$ 3,638	$ 641	$ 3,848
Depreciation and amortization	4,030	5,132	8,168	10,328
Identifiable Assets	458,360		458,360		$ 498,634
Environmental Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	31	115	40	228
Depreciation and amortization	842	907	1,687	1,874
Identifiable Assets	109,215		109,215		118,680
Energy Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	114	220	350	304
Depreciation and amortization	1,966	2,939	4,030	5,741
Identifiable Assets	229,918		229,918		257,566
Fluid Handling and Filtration Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	72	3,301	221	3,310
Depreciation and amortization	1,197	1,254	2,395	2,648
Identifiable Assets	104,924		104,924		104,294
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	14	2	30	6
Depreciation and amortization	25	$ 32	56	$ 65
Identifiable Assets	$ 14,303		$ 14,303		$ 18,094