Variable Interest Entities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Income Tax Expense (Benefit)	$ (27,100,000)	$ 33,600,000	$ (28,700,000)	$ 47,300,000
Other Assets	649,700,000		649,700,000		$ 575,900,000
Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Variable Interest Entity, Funding Investment Commitment, Funding	0	0	48,500,000	0
Distribution of Accumulated Earnings of Equity Method Limited Liability Investments	0	0	0	0
Income (Loss) from Equity Method Investments	(7,700,000)	0	(23,100,000)	0
Income Tax Credits and Adjustments	7,700,000	0	36,100,000	0
Income Tax Expense (Benefit)	900,000	$ 0	1,100,000	$ 0
Cash and Cash Equivalents, at Carrying Value	33,100,000		33,100,000
Property, Plant and Equipment, Net	121,500,000		121,500,000
Other Assets	2,800,000		2,800,000
Assets	157,400,000		157,400,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 46,600,000		$ 46,600,000