Acquisitions and Divestitures - Impact to Historical Consolidated Statements of Income Table (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other		$ 1,561,372	$ 1,382,868	[1]	$ 1,085,482	[1]
Equity income, net	[2],[3],[4]	71,251	57,836	[1]	22,948	[1]
Net income (loss)		$ (66,546)	404,688	[1]	285,974	[1]
Delaware Basin JV Gathering LLC [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other			62,112		32,545
Equity income, net			0		0
Net income (loss)			17,309		4,096
WGP Historical [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other	[5]		1,320,756		1,052,937
Equity income, net	[5]		57,836		22,948
Net income (loss)	[5]		$ 387,379		$ 281,878

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

[4] 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.

[5] See Adjustments to previously issued financial statements in Note 1.