Acquisitions and Divestitures - Impact to Historical Consolidated Statements of Income Table (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other		$ 385,101	$ 357,521	[1]	$ 1,190,082		$ 1,016,151	[1]
Equity income, net	[2],[3]	21,976	19,063	[1]	59,137	[4]	41,322	[1],[4]
Net income		$ 162,752	112,266	[1]	$ 361,264		307,943	[1]
Delaware Basin JV Gathering LLC [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other			16,239				46,124
Equity income, net			0				0
Net income			6,482				14,238
WGP Historical [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other	[5]		341,282				970,027
Equity income, net	[5]		19,063				41,322
Net income	[5]		$ 105,784				$ 293,705

[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.

[5] As adjusted for the reclassification described in Note 1.