Equity and Partners' Capital - Additional Information (details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		3 Months Ended
		Nov. 30, 2014	Jul. 31, 2014	Mar. 31, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Limited partner units owned				218,909,977	218,909,977
Anadarko [Member]
Schedule of Investments [Line Items]
Limited partner units owned				193,387,365
Ownership interest				88.30%
Anadarko [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued			5,750,000
Anadarko [Member] | Option on Securities [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued			750,000
Public [Member]
Schedule of Investments [Line Items]
Limited partner units owned				25,522,612
Ownership interest				11.70%
Western Gas Partners [Member]
Schedule of Investments [Line Items]
General partner units owned				2,583,068
General partner's interest		2.00%		1.80%
Units issued				45,711
Price per unit	[1]	$ 70.85
Western Gas Partners [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned				49,296,205
Ownership interest				34.80%
Common units issued	[1]	8,620,153
Western Gas Partners [Member] | Incentive Distribution Rights [Member]
Schedule of Investments [Line Items]
General partner's interest				100.00%
Western Gas Partners [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Units issued				45,711
Price per unit		$ 68.72
Proceeds from the issuance of WES Class C units		$ 750.0
Western Gas Partners [Member] | Class C Units [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Redeemable option on units		$ 150.0
Western Gas Partners [Member] | Option on Securities [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued		1,120,153
Western Gas Partners [Member] | Public [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned				78,123,429
Ownership interest				55.10%
Western Gas Partners [Member] | Other Subsidiaries Of Anadarko [Member]
Schedule of Investments [Line Items]
Ownership interest				8.30%
Western Gas Partners [Member] | Other Subsidiaries Of Anadarko [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned				757,619
Western Gas Partners [Member] | Other Subsidiaries Of Anadarko [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned				10,959,564
Units issued		10,913,853

[1] Includes the issuance of 1,120,153 WES common units pursuant to the partial exercise of the underwriters’ over-allotment option, the net proceeds from which were $77.0 million. Beginning with this partial exercise, WES GP elected not to make a corresponding capital contribution to maintain its 2.0% interest in WES.