Restructuring, Asset Impairment, and Transition Expenses - Reconciliation of Accrued Restructuring Costs (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 2.3	$ 4.1	$ 1.9
Restructuring expense incurred	3.0	7.4	14.1
Cash payments	(4.8)	(9.2)	(11.9)
Ending Balance	0.5	2.3	4.1
2017 Altra Plan [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0.5	1.5	1.9
Restructuring expense incurred	0.0	0.5	5.7
Cash payments	(0.5)	(1.5)	(6.1)
Ending Balance		0.5	1.5
2019 Altra Plan [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	1.8	2.6
Restructuring expense incurred	3.0	6.9	8.4
Cash payments	(4.3)	(7.7)	(5.8)
Ending Balance	$ 0.5	$ 1.8	$ 2.6