Fair Value of Financial Instruments (Schedule of Comparison of the Carrying Value and Estimated Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Assets
Cash and cash equivalents	$ 6.7	$ 4.2
Restricted cash and cash equivalents	156.6	111.3
Restricted securities available for sale	54.6	53.6
Net investment in Loans receivable	2,369.1	2,226.7
Liabilities
Revolving secured line of credit	106.2	102.8
Secured financing	1,255.1	938.9
Mortgages [Member]
Liabilities
Notes		3.8
Senior Notes [Member]
Liabilities
Notes	315.0	367.1
Carrying Amount [Member]
Assets
Cash and cash equivalents	6.7	4.2
Restricted cash and cash equivalents	156.6	111.3
Restricted securities available for sale	54.6	53.6
Net investment in Loans receivable	2,358.0	2,212.8
Liabilities
Revolving secured line of credit	106.2	102.8
Secured financing	1,248.5	935.6
Carrying Amount [Member] | Mortgages [Member]
Liabilities
Notes	0	3.8
Carrying Amount [Member] | Senior Notes [Member]
Liabilities
Notes	300.0	350.2
Estimated Fair Value [Member]
Assets
Cash and cash equivalents	6.7	4.2
Restricted cash and cash equivalents	156.6	111.3
Restricted securities available for sale	54.6	53.6
Net investment in Loans receivable	2,369.1	2,226.7
Liabilities
Revolving secured line of credit	106.2	102.8
Secured financing	1,255.1	938.9
Estimated Fair Value [Member] | Mortgages [Member]
Liabilities
Notes	0	3.8
Estimated Fair Value [Member] | Senior Notes [Member]
Liabilities
Notes	$ 315.0	$ 367.1