Equity and Partners' Capital - Additional Information (Details) $ in Millions			1 Months Ended		3 Months Ended	12 Months Ended
	May 02, 2017 shares	Mar. 01, 2017 shares	Jun. 30, 2015 $ / unit shares	Nov. 30, 2014 shares	Mar. 31, 2018 shares	Dec. 31, 2016 shares	Dec. 31, 2017 shares	Jul. 31, 2017 USD ($)
Schedule of Investments [Line Items]
Limited partner units owned					218,933,141		218,933,141
7.50% Tangible Equity Units [Member] | Anadarko [Member]
Schedule of Investments [Line Items]
Tangible equity units issued			9,200,000
Tangible equity unit rate			7.50%
Stated amount per tangible equity unit | $ / unit			50.00
Debt instrument, maturity date			Jun. 07, 2018
7.50% Tangible Equity Units [Member] | Anadarko [Member] | Over-Allotment Option [Member]
Schedule of Investments [Line Items]
Tangible equity units issued			1,200,000
Western Gas Equity Partners, LP [Member] | Public [Member]
Schedule of Investments [Line Items]
Limited partner units owned					40,345,776
Ownership interest					18.40%
Western Gas Partners, LP [Member] | Public [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned					100,458,679
Ownership interest					59.60%
Anadarko [Member] | Western Gas Equity Partners, LP [Member]
Schedule of Investments [Line Items]
Limited partner units owned					178,587,365
Ownership interest					81.60%
Western Gas Equity Partners, LP [Member] | Western Gas Partners, LP [Member]
Schedule of Investments [Line Items]
General partner units owned					2,583,068
General partner's interest					1.50%
Western Gas Equity Partners, LP [Member] | Western Gas Partners, LP [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned					50,132,046
Ownership interest					29.70%
Western Gas Equity Partners, LP [Member] | 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]
Schedule of Investments [Line Items]
Units issued					261,394
Western Gas Partners, LP [Member] | July 2017 COP [Member]
Schedule of Investments [Line Items]
Maximum aggregate principal of common units | $								$ 500.0
Western Gas Partners, LP [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Units issued					261,394
Class C units, common units issued upon conversion					1
Western Gas Partners, LP [Member] | Class C Units [Member] | Other Subsidiaries of Anadarko [Member]
Schedule of Investments [Line Items]
Units issued				10,913,853
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Series A Preferred Units March 2017 Conversion [Member]
Schedule of Investments [Line Items]
Series A Preferred units, percentage converted		50.00%
Series A Preferred units, common units issued upon conversion		1
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Series A Preferred Units May 2017 Conversion [Member]
Schedule of Investments [Line Items]
Series A Preferred units, percentage converted	50.00%
Series A Preferred units, common units issued upon conversion	1
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Private Investor [Member]
Schedule of Investments [Line Items]
Units issued						21,922,831
Other Subsidiaries of Anadarko [Member] | Western Gas Partners, LP [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned					2,011,380
Other Subsidiaries of Anadarko [Member] | Western Gas Partners, LP [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned					13,505,277
Other Subsidiaries of Anadarko [Member] | Western Gas Partners, LP [Member] | Common and Class C Units [Member]
Schedule of Investments [Line Items]
Ownership interest					9.20%