Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (3,029)	$ (38,254)	$ (5,734)
Other comprehensive income (loss), net of tax:
Translation income (loss)	4,021	(3,864)	(2,664)
Interest rate swap	180	312
Minimum pension/postretirement liability adjustment	(78)	87	(292)
Comprehensive income (loss)	1,094	(41,719)	(8,690)
Net loss attributable to noncontrolling interest		(36)	(132)
Comprehensive income (loss) attributable to CECO Environmental Corp.	$ 1,094	$ (41,683)	$ (8,558)