Restructuring, Asset Impairment, and Transition Expenses - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 4,143,000	$ 9,849,000	$ 7,214,000
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	4,143,000	9,849,000	7,214,000
2015 Altra Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	3,491,000	9,849,000	7,214,000
2015 Altra Plan [Member] | Operating Segments [Member] | Couplings, Clutches and Brakes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,849,000	7,302,000	2,527,000
2015 Altra Plan [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,600,000	2,700,000	5,200,000
2015 Altra Plan [Member] | Consolidation costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,200,000	1,700,000
2015 Altra Plan [Member] | Building impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs		900,000	$ 2,000,000
2015 Altra Plan [Member] | Moving and relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs		2,800,000
2015 Altra Plan [Member] | Other restructuring costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs		1,700,000
2015 Altra Plan [Member] | Other restructuring consolidation costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,300
2017 Altra Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	652,000
2017 Altra Plan [Member] | Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost remaining		2,000,000
2017 Altra Plan [Member] | Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost remaining		$ 4,000,000
2017 Altra Plan [Member] | Operating Segments [Member] | Couplings, Clutches and Brakes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	652,000
2017 Altra Plan [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	400,000
2017 Altra Plan [Member] | Consolidation costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 200,000