Noncontrolling Interests (Detail)	Mar. 31, 2013
Western Gas Equity Partners Limited Partnership [Member] | Limited Partner [Member]
Noncontrolling Interest [Line Items]
Ownership interest in subsidiary	91.00%
Western Gas Partners Limited Partnership [Member] | Limited Partner [Member] | Western Gas Equity Partners Limited Partnership, Ownership Interest [Member]
Noncontrolling Interest [Line Items]
Ownership interest in subsidiary	46.00%
Western Gas Partners Limited Partnership [Member] | Limited Partner [Member] | Other Anadarko Subsidiary, Ownership Interest [Member]
Noncontrolling Interest [Line Items]
Ownership interest in subsidiary	0.40%
Western Gas Partners Limited Partnership [Member] | General Partner [Member] | Western Gas Equity Partners Limited Partnership, Ownership Interest [Member]
Noncontrolling Interest [Line Items]
Ownership interest in subsidiary	2.00%