Fair Value of Assets and Liabilities (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jan. 01, 2012
Assets:
Cash and cash equivalents	$ 53,161,000	$ 31,755,000	$ 68,878,000	$ 43,377,000
Liabilities:
Non-recourse debt	93,476,000	123,482,000
Carrying Value
Assets:
Cash and cash equivalents	53,161,000	31,755,000
Restricted cash	19,126,000	34,949,000
Liabilities:
Borrowings under senior credit facility	599,250,000	797,430,000
Carrying Value | 7¾% Senior Notes
Liabilities:
Senior Notes	247,867,000	247,543,000
Carrying Value | 6.625% Senior Notes
Liabilities:
Senior Notes	300,000,000	300,000,000
Carrying Value | 5.125% Senior Notes
Liabilities:
Senior Notes	300,000,000
Carrying Value | Other non recourse debt including current portion [Member]
Liabilities:
Non-recourse debt	66,813,000	88,650,000
Total Fair Value
Assets:
Cash and cash equivalents	53,161,000	31,755,000
Restricted cash	19,126,000	34,949,000
Liabilities:
Borrowings under senior credit facility	602,991,000	803,097,000
Total Fair Value | 7¾% Senior Notes
Liabilities:
Senior Notes	261,095,000	270,313,000
Total Fair Value | 6.625% Senior Notes
Liabilities:
Senior Notes	317,064,000	335,814,000
Total Fair Value | 5.125% Senior Notes
Liabilities:
Senior Notes	276,750,000
Total Fair Value | Other non recourse debt including current portion [Member]
Liabilities:
Non-recourse debt	68,852,000	91,345,000
Level 1
Assets:
Cash and cash equivalents	53,161,000	31,755,000
Restricted cash	19,126,000	34,949,000
Liabilities:
Borrowings under senior credit facility	0	0
Level 1 | 7¾% Senior Notes
Liabilities:
Senior Notes	0	0
Level 1 | 6.625% Senior Notes
Liabilities:
Senior Notes	0	0
Level 1 | 5.125% Senior Notes
Liabilities:
Senior Notes	0
Level 1 | Other non recourse debt including current portion [Member]
Liabilities:
Non-recourse debt	0	0
Level 2
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Liabilities:
Borrowings under senior credit facility	602,991,000	803,097,000
Level 2 | 7¾% Senior Notes
Liabilities:
Senior Notes	261,095,000	270,313,000
Level 2 | 6.625% Senior Notes
Liabilities:
Senior Notes	317,064,000	335,814,000
Level 2 | 5.125% Senior Notes
Liabilities:
Senior Notes	276,750,000
Level 2 | Other non recourse debt including current portion [Member]
Liabilities:
Non-recourse debt	68,852,000	91,345,000
Level 3
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Liabilities:
Borrowings under senior credit facility	0	0
Level 3 | 7¾% Senior Notes
Liabilities:
Senior Notes	0	0
Level 3 | 6.625% Senior Notes
Liabilities:
Senior Notes	0	0
Level 3 | 5.125% Senior Notes
Liabilities:
Senior Notes	0
Level 3 | Other non recourse debt including current portion [Member]
Liabilities:
Non-recourse debt	0	0
Australian subsidiary | Carrying Value
Liabilities:
Non-recourse debt	26,759,000	34,832,000
Australian subsidiary | Total Fair Value
Liabilities:
Non-recourse debt	27,446,000	34,973,000
Australian subsidiary | Level 1
Liabilities:
Non-recourse debt	0	0
Australian subsidiary | Level 2
Liabilities:
Non-recourse debt	27,446,000	34,973,000
Australian subsidiary | Level 3
Liabilities:
Non-recourse debt	$ 0	$ 0