Fair Value of Financial Instruments (Schedule of Comparison of the Carrying Value and Estimated Fair Value of Financial Instruments) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Assets
Cash and cash equivalents	[1]	$ 8.5	$ 187.4
Restricted cash and cash equivalents	[1]	382.7	330.3
Restricted securities available for sale	[2]	67.9	59.3
Loans receivable, net	[1]	7,248.6	6,777.2
Liabilities
Revolving secured line of credit	[1]	160.5	0.0
Secured financing	[1]	3,889.6	3,397.5
Senior notes	[1]	796.1	1,257.6
Mortgage note	[1]	10.9	11.3
Carrying Amount [Member]
Assets
Cash and cash equivalents		8.5	187.4
Restricted cash and cash equivalents		382.7	330.3
Restricted securities available for sale		67.9	59.3
Loans receivable, net		6,749.8	6,685.2
Liabilities
Revolving secured line of credit		160.5	0.0
Secured financing		3,838.0	3,339.7
Senior notes		789.7	1,187.8
Mortgage note		10.9	11.3
Estimated Fair Value [Member]
Assets
Cash and cash equivalents		8.5	187.4
Restricted cash and cash equivalents		382.7	330.3
Restricted securities available for sale		67.9	59.3
Loans receivable, net		7,248.6	6,777.2
Liabilities
Revolving secured line of credit		160.5	0.0
Secured financing		3,889.6	3,397.5
Senior notes		796.1	1,257.6
Mortgage note		$ 10.9	$ 11.3

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

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