Restructuring, Asset Impairment, and Transition Expenses - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 1.6	$ 2.3
2017 Altra Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs	0.2	1.0
2019 Altra Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 1.4	$ 1.3
Expected period to incur restructuring expense	3 years
2019 Altra Plan [Member] | Minimum [Member]
Restructuring Cost And Reserve [Line Items]
Expected additional restructuring cost remaining	$ 15.0
2019 Altra Plan [Member] | Maximum [Member]
Restructuring Cost And Reserve [Line Items]
Expected additional restructuring cost remaining	20.0
Employee Severance, Consolidation and Other Restructuring Costs [Member] | 2017 Altra Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs	0.2
Severance [Member] | 2019 Altra Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs	1.1
Consolidation costs [Member] | 2019 Altra Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 0.3