Schedule II - Valuation Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at January 1	$ 1.6	$ 1.6	$ 1.6
Charged (Credited) to Expense	0.0	0.0	0.0
Deductions	0.0	0.0	0.0
Other	0.0	0.0	0.0
Balance at January 1	1.6	1.6	1.6
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at January 1	166.9	407.3	236.4
Charged (Credited) to Expense	10.9	3.3	18.6
Deductions	0.0	0.0	0.0
Other	(74.7)	(243.7)	152.3
Balance at January 1	$ 103.1	$ 166.9	$ 407.3