Fair Value Disclosure Fair Value Disclosure - Other Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	$ 9.7	$ 40.0
Short-Term Investments	0.0	148.5
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	6,248.3	6,045.1
Recourse Floating Rate Debt Fair Value Disclosure	570.0	417.8
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	5,564.2	5,309.8
Recourse Floating Rate Debt Fair Value Disclosure	$ 567.9	$ 417.0