Description of Business and Basis of Presentation - Additional Information (Details) - Western Gas Partners, LP [Member] - USD ($) $ in Millions			1 Months Ended	3 Months Ended	9 Months Ended
	Mar. 02, 2015	[1]	Nov. 30, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
General partner's interest			2.00%		1.80%
Marginal percentage interest in distributions					48.00%
Operating Income (Loss) [Member] | Restatement Adjustment [Member]
Correction of an immaterial error				$ 12.0	$ 25.0	$ 28.6
Other Subsidiaries Of Anadarko [Member]
Common units issued					757,619
Non-Operated Marcellus Interest [Member]
Ownership interest					33.75%
Anadarko-Operated Marcellus Interest [Member]
Ownership interest					33.75%
Newcastle [Member]
Ownership interest					50.00%
Delaware Basin JV Gathering LLC [Member]
Ownership interest	50.00%				50.00%
Incentive Distribution Rights [Member]
General partner's interest					100.00%
General Partner [Member]
Ownership interest					100.00%
Fort Union [Member]
Equity investment ownership					14.81%
Rendezvous [Member]
Equity investment ownership					22.00%
White Cliffs [Member]
Equity investment ownership					10.00%
Mont Belvieu JV [Member]
Equity investment ownership					25.00%
Texas Express Pipeline LLC [Member]
Equity investment ownership					20.00%
Texas Express Gathering LLC [Member]
Equity investment ownership					20.00%
Front Range Pipeline LLC [Member]
Equity investment ownership					33.33%

[1] WES acquired Anadarko’s interest in Delaware Basin JV Gathering LLC (“DBJV”), which owns a 50% interest in a gathering system and related facilities (the “DBJV system”). The DBJV system is located in the Delaware Basin in Loving, Ward, Winkler and Reeves Counties, Texas. WES will make a cash payment on March 31, 2020, to Anadarko as consideration for the acquisition of DBJV. WES currently estimates the future payment will be $282.8 million, the net present value of which was $174.3 million as of the acquisition date. See DBJV acquisition—Deferred purchase price obligation - Anadarko below.