Fair Value of Financial Instruments (Schedule of Assets and Liabilities, Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 86.7	$ 6.4
Restricted cash and cash equivalents	198.9	157.6
Restricted securities available for sale	53.0	53.2
Net investment in Loans receivable	2,739.4	2,517.3
Revolving secured line of credit		119.5
Secured financing	1,438.1	1,334.7
Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes	535.8	299.3
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	86.7	6.4
Restricted cash and cash equivalents	198.9	157.6
Restricted securities available for sale	43.0	47.8
Level 1 [Member] | Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes	535.8	299.3
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted securities available for sale	10.0	5.4
Revolving secured line of credit		119.5
Secured financing	1,438.1	1,334.7
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net investment in Loans receivable	$ 2,739.4	$ 2,517.3