CONSOLIDATED STATEMENT OF CHANGES IN PARTNERS' CAPITAL (USD $) In Thousands, unless otherwise specified	Total	Predecessor [Member]	Limited Partners-Public Common [Member]	Limited Partners-Affiliated - Common [Member]	Limited Partners-Affiliated - Subordinated [Member]	Predecesor's Capital [Member]	Predecesor's Capital [Member] Predecessor [Member]	Class C Convertible Preferred Unitholder [Member]	General Partner [Member]	General Partner [Member] Predecessor [Member]	Limited Partner [Member] Predecessor [Member]	Non-controlling Interest [Member] Predecessor [Member]
Balance at Dec. 31, 2008		$ 139,935					$ 5,957			$ 59	$ 5,898	$ 133,978
Increase (decrease) in partners' capital [Roll Forward]
Contributions by partners		15,991					1,441			14	1,427	14,550
Distributions to partners/unitholders		(27,200)					(933)			(9)	(924)	(26,267)
Net income (loss)		(115,414)					(7,886)			(79)	(7,807)	(107,528)
Balance at Dec. 31, 2009		13,312					(1,421)			(15)	(1,406)	14,733
Increase (decrease) in partners' capital [Roll Forward]
Contributions by partners		474,864					14,062			141	13,921	460,802
Distributions to partners/unitholders		(30,000)					(900)			(9)	(891)	(29,100)
Recognition of unit-based awards (See Note 11)		1,617					1,617			16	1,601	0
Net income (loss)		31,913					1,812			18	1,794	30,101
Balance at Dec. 21, 2010	354,734	491,706	0	0	0	354,734	15,170	0	0	151	15,019	476,536
Increase (decrease) in partners' capital [Roll Forward]
Contributions by partners	715		0	0	0	0		0	715
Contributions from the Predecessor (See Note 14)	53,034		0	0	0	53,034		0	0
Other contributions from affiliates (See Note 14)	666		0	113	71	482		0	0
Recognition of unit-based awards (See Note 11)	20		20	0	0	0		0	0
Distribution to the Fund	(300,000)		0	(183,767)	(116,233)	0		0	0
Net income (loss)	(12,067)		(3,181)	(2,396)	(1,515)	(4,968)		0	(7)
Book value of assets contributed by the Predecessor	0		0	137,051	86,685	(223,736)		0	0
Initital public offering	279,750		279,750	0	0	0		0	0
Deferred tax benefit as a result of IPO	299		134	101	64	0		0	0
Balance at Dec. 31, 2010	377,151		276,723	(48,898)	(30,928)	179,546		0	708
Increase (decrease) in partners' capital [Roll Forward]
Contributions from the Predecessor (See Note 14)	8,986		0	0	0	8,986		0	0
Other contributions from affiliates (See Note 14)	31,896		0	12,366	7,822	11,708		0	0
Distributions to partners/unitholders	66,571		30,673	19,854	12,557	0		3,424	63
Recognition of unit-based awards (See Note 11)	1,351		1,351	0	0	0		0	0
Reduction in units to cover individuals' tax withholding	(215)		(215)	0	0	0		0	0
Distribution to the Fund	(42,000)		0	(25,727)	(16,273)	0		0	0
Net income (loss)	61,137		1,648	1,079	682	49,091		7,062	1,575
Proceeds from over-allotment	41,963		41,963	0	0	0		0	0
Book value of assets contributed by the Predecessor	(249,331)		0	0	0	(249,331)		0	0
Fair value of Preferred Units issued to the Fund	354,500		0	0	0	0		354,500	0
Fair value of Preferred Units in excess of net assets received from the Fund	(102,454)		(49,491)	(32,380)	(20,481)	0		0	(102)
Amortization of discount on increasing rate distributions	3,638		0	0	0	0		3,638	0
Noncash distribution to preferred unitholders	(3,638)		0	0	0	0		(3,638)	0
Management incentive fee earned	(1,572)		0	0	0	0		0	(1,572)
Balance at Dec. 31, 2011	$ 414,841		$ 241,306	$ (113,414)	$ (71,735)	$ 0		$ 358,138	$ 546