Goodwill and Intangible Assets - Goodwill / Tradename (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill, beginning balance		$ 170,153	$ 220,163
Goodwill, acquisitions and related adjustments			4,205
Goodwill, impairment charge		(4,443)	(53,762)
Goodwill, foreign currency translation		1,241	(453)
Goodwill, ending balance	$ 166,951	166,951	170,153
Tradename, beginning balance		22,042	26,337
Tradename, impairment charge		(2,725)	(4,161)
Tradename, foreign currency adjustments		374	(134)
Tradename, ending balance	19,691	19,691	22,042
Energy Segment [Member]
Goodwill [Line Items]
Goodwill, beginning balance		75,827	72,075
Goodwill, acquisitions and related adjustments			4,205
Goodwill, impairment charge	(4,400)	(4,443)
Goodwill, foreign currency translation		1,241	(453)
Goodwill, ending balance	72,625	72,625	75,827
Environmental Segment [Member]
Goodwill [Line Items]
Goodwill, beginning balance		48,203	55,031
Goodwill, impairment charge			(6,828)
Goodwill, ending balance	48,203	48,203	48,203
Fluid Handling and Filtration Segment [Member]
Goodwill [Line Items]
Goodwill, beginning balance		46,123	93,057
Goodwill, impairment charge			(46,934)
Goodwill, ending balance	$ 46,123	$ 46,123	$ 46,123