Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Assets:
Receivable, fair value	$ 20,983	$ 0
Level 3 | Carrying Value
Liabilities:
Non-recourse debt	2,702,133	1,492,410
Level 3 | Fair Value
Liabilities:
Non-recourse debt	2,720,181	1,477,497
Level 3 | Notes Receivable | Carrying Value
Assets:
Receivable, fair value	20,983	0
Level 3 | Notes Receivable | Fair Value
Assets:
Receivable, fair value	19,988	0
Level 3 | Deferred acquisition fees receivable | Carrying Value
Assets:
Receivable, fair value	19,585	19,684
Level 3 | Deferred acquisition fees receivable | Fair Value
Assets:
Receivable, fair value	22,188	20,733
Level 2 | Senior Unsecured Notes | Carrying Value
Liabilities:
Non-recourse debt	498,300	0
Level 2 | Senior Unsecured Notes | Fair Value
Liabilities:
Non-recourse debt	518,523	0
Level 2 | Senior Unsecured Credit Facility | Carrying Value
Liabilities:
Lines of Credit, Fair Value Disclosure	618,945	275,000
Level 2 | Senior Unsecured Credit Facility | Fair Value
Liabilities:
Lines of Credit, Fair Value Disclosure	618,945	275,000
Level 2 | Unsecured Term Loan | Carrying Value
Liabilities:
Lines of Credit, Fair Value Disclosure	0	300,000
Level 2 | Unsecured Term Loan | Fair Value
Liabilities:
Lines of Credit, Fair Value Disclosure	$ 0	$ 300,000