Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 16.4	$ 18.0	$ 21.4
Charged to costs and expenses	0.7	0.1	(2.3)
Deductions	(0.9)	(1.7)	(1.1)
Balance at end of period	16.2	16.4	18.0
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	15.9	16.0	20.9
Charged to costs and expenses	0.0	0.0	(3.0)
Deductions	(0.8)	(0.1)	(1.9)
Balance at end of period	15.1	15.9	16.0
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	0.5	2.0	0.5
Charged to costs and expenses	0.7	0.1	0.7
Deductions	(0.1)	(1.6)	0.8
Balance at end of period	$ 1.1	$ 0.5	$ 2.0