Schedule II - Valuation Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 1.6	$ 1.6	$ 1.6
Charged to Expense	0.0	0.0	0.0
Deductions	0.0	0.0	0.0
Other	0.0	0.0	0.0
Ending balance	1.6	1.6	1.6
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	103.1	166.9	407.3
Charged to Expense	3.3	10.9	3.3
Deductions	0.0	0.0	0.0
Other	0.0	(74.7)	(243.7)
Ending balance	$ 106.4	$ 103.1	$ 166.9