Members' Equity Members' Equity - AOCI (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive loss, beginning balance			$ (25,672)	$ (20,154)
Other comprehensive income before reclassifications:
Deferred losses on interest rate swaps	(4,468)	(5,705)	1,125	(18,626)
Unrealized gain (loss) on available-for-sale securities	(57)	86	(173)	200
Other comprehensive income before reclasifications			952	(18,426)
Reclassification of deferred losses on interest rate swaps into income	3,346	3,930	9,821	10,225
Other comprehensive (loss) income for the period, net			10,773	(8,201)
Accumulated other comprehensive loss, ending balance	(14,899)	(28,355)	(14,899)	(28,355)
Interest Rate Swap [Member]
Other comprehensive income before reclassifications:
Deferred losses on interest rate swaps			1,125	(18,626)
Reclassification of deferred losses on interest rate swaps into income			9,821	10,225
Unrealized Losses on Interest Rate Swaps [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive loss, beginning balance			(25,778)	(20,047)
Other comprehensive income before reclassifications:
Other comprehensive income before reclasifications			1,125	(18,626)
Other comprehensive (loss) income for the period, net			10,946	(8,401)
Accumulated other comprehensive loss, ending balance	(14,832)	(28,448)	(14,832)	(28,448)
Unrealized Losses on Interest Rate Swaps [Member] | Interest Rate Swap [Member]
Other comprehensive income before reclassifications:
Deferred losses on interest rate swaps			1,125	(18,626)
Reclassification of deferred losses on interest rate swaps into income			9,821	10,225
Unrealized Gain (Loss) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive loss, beginning balance			106	(107)
Other comprehensive income before reclassifications:
Unrealized gain (loss) on available-for-sale securities			(173)	200
Other comprehensive income before reclasifications			(173)	200
Other comprehensive (loss) income for the period, net			(173)	200
Accumulated other comprehensive loss, ending balance	$ (67)	$ 93	$ (67)	$ 93