Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 222.9	$ 4.8
Intangible Assets, Net (Excluding Goodwill)	215.2	1.2
Other assets
Prepaid Expense, Current	16.3	19.3
Income Taxes Receivable, Current	315.3	74.2
Other Assets, Miscellaneous, Current	4.7	5.2
Other Assets, Current	336.3	98.7
Deferred financing costs	0.9	41.7
Less: Accumulated amortization-deferred financing costs	(0.5)	(36.9)
Deferred financing costs, net	0.4	4.8
Equity in net assets of affiliates	3.1	11.5
Equity in net assets of affiliates	11.4	7.7
Restricted Cash and Investments, Noncurrent	19.5	16.4	$ 20.2	$ 20.0
Other	49.2	36.4
Goodwill	565.3	2.4
Total	83.6	76.8
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	2.0	2.0
Finite-Lived Intangible Assets, Accumulated Amortization	(2.0)	(1.9)
Favorable Leasehold [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	2.8	2.8
Finite-Lived Intangible Assets, Accumulated Amortization	(1.8)	(1.7)
Developed Technology
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	94.0	0.0
Finite-Lived Intangible Assets, Accumulated Amortization	(2.6)	0.0
Customer Contracts
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	124.1	0.0
Finite-Lived Intangible Assets, Accumulated Amortization	$ (1.3)	$ 0.0