Fair Value Disclosure Fair Value Disclosure - Other Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	$ 16.2	$ 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	5,822.2	6,045.1
Recourse Floating Rate Debt Fair Value Disclosure	569.2	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	5,222.5	5,309.8
Recourse Floating Rate Debt Fair Value Disclosure	$ 567.1	$ 417.0