Business Segment Information - Intra-Segment and Inter-Segment Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Net sales	$ 98,230	$ 63,300	$ 266,176	$ 187,111
Environmental Segment [Member]
Segment Reporting Information [Line Items]
Net sales	40,644	27,709	124,158	87,396
Energy Segment [Member]
Segment Reporting Information [Line Items]
Net sales	40,014	17,977	91,666	50,093
Fluid Handling and Filtration Segment [Member]
Segment Reporting Information [Line Items]
Net sales	17,136	17,584	50,075	49,729
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net sales	436	30	277	(107)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	102,090	67,289	278,199	198,194
Operating Segments [Member] | Environmental Segment [Member]
Segment Reporting Information [Line Items]
Net sales	42,925	29,920	130,315	93,580
Operating Segments [Member] | Energy Segment [Member]
Segment Reporting Information [Line Items]
Net sales	41,511	19,193	96,037	53,503
Operating Segments [Member] | Fluid Handling and Filtration Segment [Member]
Segment Reporting Information [Line Items]
Net sales	17,654	18,176	51,847	51,111
Inter-segment Elimination [Member]
Segment Reporting Information [Line Items]
Net sales	(3,842)	(3,398)	(10,531)	(9,828)
Inter-segment Elimination [Member] | Environmental Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(101)	(44)	(823)	(88)
Inter-segment Elimination [Member] | Energy Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(345)	(444)	(938)	(766)
Inter-segment Elimination [Member] | Fluid Handling Filtration Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(8)	(133)	(8)	(294)
Inter-segment Elimination [Member] | Corporate And Other Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	436	30	277	(107)
Inter-segment Elimination [Member] | Environmental Segment [Member]
Segment Reporting Information [Line Items]
Net sales	(1,928)	(1,634)	(5,211)	(5,124)
Inter-segment Elimination [Member] | Environmental Segment [Member] | Energy Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(345)	(444)	(938)	(766)
Inter-segment Elimination [Member] | Environmental Segment [Member] | Fluid Handling Filtration Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(8)	(133)	(8)	(294)
Inter-segment Elimination [Member] | Energy Segment [Member]
Segment Reporting Information [Line Items]
Net sales	(1,490)	(1,200)	(3,745)	(3,393)
Inter-segment Elimination [Member] | Energy Segment [Member] | Environmental Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(7)	(16)	(626)	(17)
Inter-segment Elimination [Member] | Fluid Handling and Filtration Segment [Member]
Segment Reporting Information [Line Items]
Net sales	(424)	(564)	(1,575)	(1,311)
Inter-segment Elimination [Member] | Fluid Handling and Filtration Segment [Member] | Environmental Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	(94)	(28)	(197)	(71)
Inter-segment Elimination [Member] | Corporate and Other [Member] | Corporate And Other Inter-Segment Sales [Member]
Segment Reporting Information [Line Items]
Net sales	$ 436	$ 30	$ 277	$ (107)