Fair Value of Financial Instruments (Schedule of Assets and Liabilities, Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	[1]	$ 25.7	$ 187.4
Restricted cash and cash equivalents	[1]	408.1	330.3
Restricted securities available for sale	[2]	63.2	59.3
Loans receivable, net	[1]	7,044.3	6,777.2
Revolving secured line of credit	[1]	79.9	0.0
Secured financing	[1]	3,915.7	3,397.5
Senior notes	[1]	738.6	1,257.6
Mortgage note	[1]	11.1	11.3
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	[1]	25.7	187.4
Restricted cash and cash equivalents	[1]	408.1	330.3
Restricted securities available for sale	[2]	48.9	47.5
Senior notes	[1]	738.6	1,257.6
Mortgage note	[1]	0.0	0.0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted securities available for sale	[2]	14.3	11.8
Revolving secured line of credit	[1]	79.9	0.0
Secured financing	[1]	3,915.7	3,397.5
Mortgage note	[1]	11.1	11.3
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans receivable, net	[1]	$ 7,044.3	$ 6,777.2

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

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