Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 316,011	$ 341,869	$ 337,339
Cost of sales	210,883	227,770	225,802
Gross profit	105,128	114,099	111,537
Selling and administrative expenses	76,926	85,978	87,462
Amortization and earnout expenses	8,799	8,499	9,683
Restructuring expenses	2,331	1,097
Acquisition and integration expenses	1,354	465
Executive transition expenses	1,522
Loss on divestitures, net of selling costs		70	4,390
Intangible asset impairment	850	0	0
Income from operations	13,346	17,990	10,002
Other income (expense), net	2,033	751	(365)
Interest expense	(3,535)	(5,397)	(7,140)
Income before income taxes	11,844	13,344	2,497
Income tax expense (benefit)	3,672	(4,363)	9,618
Net income (loss)	8,172	17,707	(7,121)
Noncontrolling interest	39
Net income (loss) attributable to CECO Environmental Corp.	$ 8,211	$ 17,707	$ (7,121)
Income (loss) per share:
Basic	$ 0.23	$ 0.51	$ (0.21)
Diluted	$ 0.23	$ 0.50	$ (0.21)
Weighted average number of common shares outstanding:
Basic	35,289,616	34,987,878	34,714,395
Diluted	35,520,670	35,484,273	34,714,395