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		$ 402,412	$ 345,569	[1]	$ 777,506		$ 639,286	[1]
Equity income, net	[2],[3]	18,941	13,008	[1]	37,161	[4]	22,259	[1],[4]
Net income		$ 112,546	101,881	[1]	$ 198,512		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			4,135				7,756
WGP Historical [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues			329,944				609,401
Equity income, net			13,008				22,259
Net income			$ 97,746				$ 187,921

[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.

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