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 (loss)		165,735	112,266	[1]	103,991		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 (loss)			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 (loss)		$ 162,752	$ 105,784	[5]	$ 361,264		$ 293,705	[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.