Segment Information (Schedule of Segment Reporting Information, by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Revenue:
Revenues - third party	$ 407,841	$ 292,207
Revenues - affiliates	71	79
Total revenues	407,912	292,286
Costs and expenses:
Operating costs and expenses	347,399	247,250
General and administrative	13,798	9,945
Other costs	530	(34)
Depreciation and amortization	30,458	20,842
Interest expense	18,686	8,708
Total costs and expenses	410,871	286,711
Equity income	2,040	896
Loss on early extinguishment of debt	(26,582)	0
Income (loss) before tax	(27,501)	6,471
Income tax benefit	(9)	0
Net income (loss)	(27,492)	6,471
Capital expenditures	108,516	81,167
Schedule of Assets, by Segment
Equity method investment in joint venture	86,242		86,002
Goodwill	319,285		319,285
Total assets	3,154,430		3,065,638
Gathering and Processing [Member]
Revenue:
Revenues - third party	418,607	305,388
Revenues - affiliates	71	79
Total revenues	418,678	305,467
Costs and expenses:
Operating costs and expenses	347,055	247,167
Other costs		(34)
Depreciation and amortization	29,971	20,842
Total costs and expenses	377,026	267,975
Income tax benefit	(9)
Net income (loss)	41,661	37,492
Capital expenditures	108,393	81,167
Schedule of Assets, by Segment
Goodwill	292,448		292,448
Total assets	2,926,959		2,831,639
Transportation, Treating and Other [Member]
Revenue:
Revenues - third party	1,433
Total revenues	1,433
Costs and expenses:
Operating costs and expenses	344	83
Depreciation and amortization	268
Total costs and expenses	612	83
Equity income	2,040	896
Net income (loss)	2,861	813
Capital expenditures	123
Schedule of Assets, by Segment
Equity method investment in joint venture	86,242		86,002
Goodwill	26,837		26,837
Total assets	139,809		141,356
Corporate and Other [Member]
Revenue:
Revenues - third party	(12,199)	(13,181)
Total revenues	(12,199)	(13,181)
Costs and expenses:
General and administrative	13,798	9,945
Other costs	530
Depreciation and amortization	219
Interest expense	18,686	8,708
Total costs and expenses	33,233	18,653
Loss on early extinguishment of debt	(26,582)
Net income (loss)	(72,014)	(31,834)
Schedule of Assets, by Segment
Total assets	87,662		92,643
Parent Company [Member]
Costs and expenses:
Total costs and expenses	18,596	8,350
Equity income	16,317	13,285
Loss on early extinguishment of debt	(26,582)
Income (loss) before tax	(28,861)
Net income (loss)	(28,861)	4,935
Schedule of Assets, by Segment
Total assets	$ 2,870,028		$ 2,785,022