Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 345,051	$ 417,011	$ 367,422
Cost of sales	231,857	282,152	258,251
Gross profit	113,194	134,859	109,171
Selling and administrative expenses	88,975	81,743	67,329
Acquisition and integration expenses		524	7,940
Amortization and earnout expenses	7,132	20,231	25,613
Intangible asset and goodwill impairment	7,168	57,923	3,340
Restructuring expenses	1,895
Income (loss) from operations	8,024	(25,562)	4,949
Other income (expense), net	106	310	(2,081)
Interest expense	(6,721)	(7,712)	(5,964)
Income (loss) before income taxes	1,409	(32,964)	(3,096)
Income tax expense	4,438	5,290	2,638
Net loss	(3,029)	(38,254)	(5,734)
Net loss attributable to noncontrolling interest		(36)	(132)
Net loss attributable to CECO Environmental Corp.	$ (3,029)	$ (38,218)	$ (5,602)
Loss per share:
Basic	$ (0.09)	$ (1.12)	$ (0.19)
Diluted	$ (0.09)	$ (1.12)	$ (0.19)
Weighted average number of common shares outstanding:
Basic	34,445,256	33,979,549	28,791,662
Diluted	34,445,256	33,979,549	28,791,662