Fair Value of Financial Instruments (Schedule of Comparison of the Carrying Value and Estimated Fair Value of Financial Instruments) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents	[1]	$ 45.7	$ 16.0
Restricted cash and cash equivalents	[1]	538.5	380.2
Restricted securities available for sale	[2]	68.1	66.1
Loans receivable, net	[1]	7,254.1	7,216.4
Liabilities
Revolving secured line of credit	[1]	0.0	95.9
Secured financing	[1]	3,993.6	3,793.9
Senior notes	[1]	829.5	842.0
Mortgage note	[1]	10.3	10.5
Carrying Amount [Member]
Assets
Cash and cash equivalents		45.7	16.0
Restricted cash and cash equivalents		538.5	380.2
Restricted securities available for sale		68.1	66.1
Loans receivable, net		6,875.3	6,787.9
Liabilities
Revolving secured line of credit		0.0	95.9
Secured financing		3,914.6	3,711.6
Senior notes		791.1	790.6
Mortgage note		10.3	10.5
Estimated Fair Value [Member]
Assets
Cash and cash equivalents		45.7	16.0
Restricted cash and cash equivalents		538.5	380.2
Restricted securities available for sale		68.1	66.1
Loans receivable, net		7,254.1	7,216.4
Liabilities
Revolving secured line of credit		0.0	95.9
Secured financing		3,993.6	3,793.9
Senior notes		829.5	842.0
Mortgage note		$ 10.3	$ 10.5

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

[2] Measured at fair value on a recurring basis.