Business Segment Information - Property and Equipment Additions, Depreciation and Amortization and Identifiable Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Property and equipment additions	$ 1,151	$ 1,377	$ 273
Depreciation and amortization	11,268	6,647	1,250
Identifiable Assets	414,365	349,210
Air Pollution Control Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	486	266	225
Depreciation and amortization	2,263	1,264	747
Identifiable Assets	133,899	74,556
Energy Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	136	476	26
Depreciation and amortization	2,329	2,174	255
Identifiable Assets	91,850	76,960
Fluid Handling Filtration Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	486	628
Depreciation and amortization	6,545	3,048	36
Identifiable Assets	172,779	186,320
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	43	7	22
Depreciation and amortization	131	161	212
Identifiable Assets	$ 15,837	$ 11,374