Fair Value Disclosure Fair Value Disclosure - Other Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$ 8,600.6	$ 7,861.2
Recourse Debt	8,751.3	8,215.3
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	8,002.7	7,609.5
Recourse Floating Rate Debt Fair Value Disclosure	748.6	605.8
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	7,841.4	7,243.9
Recourse Floating Rate Debt Fair Value Disclosure	$ 759.2	$ 617.3