Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning Balance	$ 5.6	$ 4.2	$ 7.1
Charge to Expenses	5.5	4.2	1.1
Charged (credited) to other accounts	(0.1)	(0.1)	0.4
Deductions	(1.9)	(2.7)	(4.4)
Balance at end of period	9.1	5.6	4.2
Tax Valuation Allowance [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning Balance	171.2	189.4	149.8
Additions Charged to Income	24.6	33.1	25.8
Additions Charged to Equity	(1.0)	(10.4)	13.8
Deductions	0.0	(40.9)	0.0
Balance at end of period	$ 194.8	$ 171.2	$ 189.4