Fair Value Disclosure Fair Value Disclosure - Other Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	$ 4,153.8	$ 4,389.3
Recourse Floating Rate Debt Fair Value Disclosure	915.6	417.5
Lines of Credit, Fair Value Disclosure	250.0
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Recourse Fixed Rate Debt Fair Value Disclosure	4,354.7	4,644.6
Recourse Floating Rate Debt Fair Value Disclosure	911.8	$ 419.0
Line of Credit Facility, Fair Value of Amount Outstanding	$ 248.9