Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits – January 1	$ 41.5	$ 46.2	$ 45.8
Additions for:
Current year tax positions	0.6	0.9	1.5
Prior year tax positions	0.1	0.3	0.3
Reductions for:
Prior year tax positions	(5.5)	0.0	(0.1)
Expiration of statute of limitations	(19.7)	(4.7)	(1.2)
Settlements	(9.4)	(1.2)	(0.1)
Unrecognized tax benefits – December 31	$ 7.6	$ 41.5	$ 46.2