SCHEDULE II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-09, Allowance, Credit Loss
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year		$ 2.9	$ 2.4	$ 1.6
Charged to Costs and Expenses		0.3	2.4	1.9
Charged to Other Accounts	[1]	0.0	0.0	0.0
Deductions	[2]	(1.1)	(1.9)	(1.1)
Balance at End of Year		2.1	2.9	2.4
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year		8.8	8.2	9.4
Charged to Costs and Expenses		(3.6)	0.1	(0.8)
Charged to Other Accounts	[1]	(0.1)	0.5	(0.4)
Deductions	[2]	0.0	0.0	0.0
Balance at End of Year		$ 5.1	$ 8.8	$ 8.2

[1] epresents amounts recognized in Accumulated other comprehensive loss and other adjustments that had no net impact on Income tax expense in the year.

[2] Represents amounts written off, net of related recoveries.