Acquisitions Narrative (Details) (USD $)	3 Months Ended			2 Months Ended		0 Months Ended			2 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 30, 2013	Mar. 31, 2014 Hoover Energy [Member]	Feb. 03, 2014 Hoover Energy [Member]	Mar. 31, 2014 PVR [Member]	Mar. 21, 2014 PVR [Member]	Dec. 23, 2013 Eagle Rock [Member]	Mar. 31, 2014 Private Common Unit Offering [Member] Hoover Energy [Member]
Business Acquisition, Transaction Costs							$ 36,100,000
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds			1,500,000,000		293,200,000		5,700,000,000	1,300,000,000
Partners' Capital Account, Units, Sold in Private Placement									4,040,471
Business Combination, Acquisition Related Costs				183,600,000
Asset Retirement Obligation					2,000,000
Revenues	863,000,000	540,000,000		5,000,000		37,000,000
Net Income (Loss) Attributable to Parent	9,000,000	(29,000,000)		2,000,000		2,000,000
Business Acquisition, Share Price							$ 27.82
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities							$ 1,800,000,000
Number of Share Received in Exchange of Each Share							1.02