Equity and Partners' Capital - Additional Information (Details) $ / shares in Units, $ in Millions		1 Months Ended			6 Months Ended
		Jun. 30, 2015 $ / unit shares	Nov. 30, 2014 USD ($) $ / shares shares	Jul. 31, 2014 shares	Jun. 30, 2015 $ / unit shares	Dec. 31, 2014 shares
Schedule of Investments [Line Items]
Limited partner units owned		218,913,688			218,913,688	218,909,977
Anadarko [Member]
Schedule of Investments [Line Items]
Limited partner units owned		191,087,365			191,087,365
Ownership interest					87.30%
Anadarko [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued		2,300,000		5,750,000
Anadarko [Member] | Option on Securities [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued		300,000		750,000
Anadarko [Member] | Tangible Equity Units [Member]
Schedule of Investments [Line Items]
Tangible equity units issued		9,200,000
Tangible equity unit rate		7.50%			7.50%
Stated amount per tangible equity unit | $ / unit		50.00			50.00
Debt instrument, maturity date					Jun. 07, 2018
Anadarko [Member] | Tangible Equity Units [Member] | Option on Securities [Member]
Schedule of Investments [Line Items]
Tangible equity units issued		1,200,000
Public [Member]
Schedule of Investments [Line Items]
Limited partner units owned		27,826,323			27,826,323
Ownership interest					12.70%
Western Gas Partners, LP [Member]
Schedule of Investments [Line Items]
General partner units owned		2,583,068			2,583,068
General partner's interest			2.00%		1.80%
Units issued					163,941
Price per unit | $ / shares	[1]		$ 70.85
Western Gas Partners, LP [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned		49,296,205			49,296,205
Ownership interest					34.70%
Common units issued	[1]		8,620,153
Western Gas Partners, LP [Member] | Incentive Distribution Rights [Member]
Schedule of Investments [Line Items]
General partner's interest					100.00%
Western Gas Partners, LP [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Units issued					163,941
Price per unit | $ / shares			$ 68.72
Proceeds from the issuance of Class C units | $			$ 750.0
Western Gas Partners, LP [Member] | Class C Units [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Redeemable option on units | $			$ 150.0
Western Gas Partners, LP [Member] | Option on Securities [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued			1,120,153
Western Gas Partners, LP [Member] | Public [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned		78,520,822			78,520,822
Ownership interest					55.20%
Western Gas Partners, LP [Member] | Other Subsidiaries Of Anadarko [Member]
Schedule of Investments [Line Items]
Ownership interest					8.30%
Western Gas Partners, LP [Member] | Other Subsidiaries Of Anadarko [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned		757,619			757,619
Western Gas Partners, LP [Member] | Other Subsidiaries Of Anadarko [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned		11,077,794			11,077,794
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.