Restructuring, Asset Impairment, and Transition Expenses - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 566,000	$ 1,198,000	$ 1,509,000	$ 3,096,000
2015 Altra Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	$ 1,198,000		$ 3,096,000
2017 Altra Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	566,000		1,509,000
2017 Altra Plan [Member] | Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Expected additional restructuring cost remaining	1,000,000		1,000,000
2017 Altra Plan [Member] | Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Expected additional restructuring cost remaining	$ 3,000,000		$ 3,000,000