Fair Value Disclosure Fair Value Disclosure - Other Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$ 8,131.5	$ 6,977.5
Recourse Debt	8,293.5	7,388.1
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	7,701.8	7,026.6
Recourse Floating Rate Debt Fair Value Disclosure	591.7	361.5
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	7,530.6	6,614.6
Recourse Floating Rate Debt Fair Value Disclosure	$ 600.9	$ 362.9