Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets:
Receivable, fair value	$ 21,058	$ 0
Level 3
Liabilities:
Non-recourse debt	2,950,978	1,477,497
Level 3 | Carrying Value
Liabilities:
Non-recourse debt	2,961,999	1,492,410
Level 3 | Notes Receivable
Assets:
Receivable, fair value	21,512	0
Level 3 | Notes Receivable | Carrying Value
Assets:
Receivable, fair value	21,058	0
Level 3 | Deferred acquisition fees receivable
Assets:
Receivable, fair value	21,364	20,733
Level 3 | Deferred acquisition fees receivable | Carrying Value
Assets:
Receivable, fair value	20,479	19,684
Level 3 | Senior Unsecured Credit Facility
Liabilities:
Lines of Credit, Fair Value Disclosure	366,278	275,000
Level 3 | Senior Unsecured Credit Facility | Carrying Value
Liabilities:
Lines of Credit, Fair Value Disclosure	366,278	275,000
Level 3 | Unsecured Term Loan
Liabilities:
Lines of Credit, Fair Value Disclosure	0	300,000
Level 3 | Unsecured Term Loan | Carrying Value
Liabilities:
Lines of Credit, Fair Value Disclosure	0	300,000
Level 2 | Senior Unsecured Notes
Liabilities:
Non-recourse debt	498,210	0
Level 2 | Senior Unsecured Notes | Carrying Value
Liabilities:
Non-recourse debt	$ 498,210	$ 0