Cash Distributions and Net Income (Loss) per Common Unit (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss	$ (63,521)	$ (42,422)	$ (24,861)	$ (19,332)	$ (7,463)	$ (14,479)	$ (6,868)	$ (2,209)	$ (150,136)	$ (31,019)	$ 107,568
Declared distributions									61,501	50,136	104,538
Amortization ofbeneficial conversion feature of Class B units									0
Assumed allocation of undistributed net loss									(211,637)	(81,155)	3,030
Weighted average units outstanding										27,910	26,416
Net income (loss) per common unit	$ (0.06)	$ 0.04	$ 0.17	$ 0.23	$ 0.30	$ 0.29	$ 0.32	$ 0.35		$ 1.23	$ 1.70
Subordinated Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss									(114,678)	(25,301)	88,206
Declared distributions									0	0	57,538
Amortization ofbeneficial conversion feature of Class B units									(20,170)
Assumed allocation of undistributed net loss									(157,917)	(64,713)	2,969
Assumed allocation of net income (loss)									(178,087)	(64,713)	60,507
Weighted average units outstanding									135,384	135,384	135,384
Net income (loss) per common unit									$ (1.32)	$ (0.48)	$ 0.45
Class B Unit [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Declared distributions									0	0	0
Amortization ofbeneficial conversion feature of Class B units									25,319
Assumed allocation of undistributed net loss									0	0	0
Assumed allocation of net income (loss)									25,319	0	0
Weighted average units outstanding									43,303	0	0
Net income (loss) per common unit									$ 0.58	$ 0.00	$ 0.00
General Partner [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss									(7,107)	(620)	2,151
Declared distributions									1,230	1,002	2,090
Amortization ofbeneficial conversion feature of Class B units									0
Assumed allocation of undistributed net loss									(7,659)	(1,623)	61
Assumed allocation of net income (loss)									(6,429)	(621)	2,151
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss									(28,351)	(5,098)	17,211
Declared distributions									60,271	49,134	44,910
Amortization ofbeneficial conversion feature of Class B units									(5,149)
Assumed allocation of undistributed net loss									(46,061)	(14,819)	0
Assumed allocation of net income (loss)									$ 9,061	$ 34,315	$ 44,910
Weighted average units outstanding									33,470	27,910	26,416
Net income (loss) per common unit									$ 0.27	$ 1.23	$ 1.70