Fair Value of Financial Instruments (Schedule of Comparison of the Carrying Value and Estimated Fair Value of Financial Instruments) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	[1]	$ 10.7	$ 23.3
Restricted cash and cash equivalents	[1]	384.7	410.9
Debt Securities, Available-for-sale, Restricted		68.0	62.1
Loans receivable, net	[1]	6,741.5	6,580.4
Liabilities
Revolving secured line of credit	[1]	188.9	2.6
Secured financing	[1]	3,509.5	3,832.1
Senior notes	[1]	745.0	825.8
Mortgage note	[1]	9.0	9.7
Carrying Amount [Member]
Assets
Cash and cash equivalents		10.7	23.3
Restricted cash and cash equivalents		384.7	410.9
Debt Securities, Available-for-sale, Restricted		68.0	62.1
Loans receivable, net		6,311.6	6,336.3
Liabilities
Revolving secured line of credit		188.9	2.6
Secured financing		3,634.1	3,811.5
Senior notes		793.9	792.5
Mortgage note		9.0	9.7
Estimated Fair Value [Member]
Assets
Cash and cash equivalents		10.7	23.3
Restricted cash and cash equivalents		384.7	410.9
Debt Securities, Available-for-sale, Restricted		68.0	62.1
Loans receivable, net		6,741.5	6,580.4
Liabilities
Revolving secured line of credit		188.9	2.6
Secured financing		3,509.5	3,832.1
Senior notes		745.0	825.8
Mortgage note		$ 9.0	$ 9.7

[1] Measured at amortized cost with fair value disclosed.