Acquisitions and Divestitures - Impact to Historical Consolidated Statement of Income Table (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		$ 416,572	$ 357,381	[1]	$ 804,981		$ 658,630	[1]
Equity income, net	[2],[3]	18,941	13,008	[1]	37,161	[4]	22,259	[1],[4]
Net income (loss)		115,648	101,881	[1]	(61,744)		195,677	[1]
Delaware Basin JV Gathering LLC [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues			15,625				29,885
Equity income, net			0				0
Net income (loss)			4,135				7,756
WGP Historical [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues	[5]		341,756				628,745
Equity income, net	[5]		13,008				22,259
Net income (loss)		$ 112,546	$ 97,746	[5]	$ 198,512		$ 187,921	[5]

[1] Financial information has been recast to include the financial position and results attributable to the DBJV system. See Note 1 and Note 2.

[2] Income earned from equity investments is classified as affiliate. See Note 1.

[3] Represents amounts earned or incurred on and subsequent to the date of acquisition of WES assets, as well as amounts earned or incurred by Anadarko on a historical basis related to WES assets prior to the acquisition of such assets by WES, recognized under gathering, treating or processing agreements, and purchase and sale agreements. See Adjustments to Previously Issued Financial Statements in Note 1.

[4] Income earned on, distributions from and contributions to equity investments are classified as affiliate. See Note 1.

[5] See Adjustments to Previously Issued Financial Statements in Note 1.