Quarterly Data (Unaudited) - Schedule of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 99,982	$ 101,596	$ 112,258	$ 103,175	$ 101,246	$ 98,230	$ 86,961	$ 80,985	$ 417,011	$ 367,422	$ 263,217
Gross profit	35,667	33,676	33,930	31,586	30,773	30,795	26,628	20,975	134,859	109,171	84,823
Net income (loss)	(51,172)	5,826	4,037	3,055	(3,211)	(4,825)	2,104	198	$ (38,218)	$ (5,602)	$ 13,077
Net income (loss) attributable to CECO Environmental Corp.	$ (51,172)	$ 5,804	$ 4,050	$ 3,100	$ (3,079)	$ (4,825)	$ 2,104	$ 198
Basic earnings (loss) per share	$ (1.49)	$ 0.17	$ 0.12	$ 0.09	$ (0.09)	$ (0.17)	$ 0.08	$ 0.01	$ (1.12)	$ (0.19)	$ 0.51
Diluted earnings (loss) per share	$ (1.49)	$ 0.17	$ 0.12	$ 0.09	$ (0.09)	$ (0.17)	$ 0.08	$ 0.01	$ (1.12)	$ (0.19)	$ 0.50