Equity and Partners' Capital - Additional Information (details) (USD $) In Millions, except Share data, unless otherwise specified			3 Months Ended			1 Months Ended	3 Months Ended			1 Months Ended	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Common [Member] Western Gas Partners [Member]	Mar. 31, 2013 Common [Member] Public [Member]	Mar. 31, 2013 Common [Member] Public [Member] Western Gas Partners [Member]	Jun. 30, 2012 Common [Member] Public [Member] June 2012 Equity Offering [Member] Western Gas Partners [Member]	Mar. 31, 2013 Common [Member] Anadarko [Member]	Mar. 31, 2013 Common [Member] Anadarko Marcellus Midstream [Member] Western Gas Partners [Member]	Mar. 31, 2013 General Partner Member Western Gas Partners [Member]	Jun. 30, 2012 General Partner Member June 2012 Equity Offering [Member] Western Gas Partners [Member]	Mar. 31, 2013 Incentive Distribution Rights [Member] Western Gas Partners [Member]
Schedule Of Investments Line Items
Units Issued						5,000,000				102,041
Price per unit						$ 43.88
General partner's interest									2.00%		100.00%
Net proceeds						$ 216.4
Units owned	218,895,515	218,895,515	49,296,205	19,758,150	55,364,348		199,137,365	449,129
Ownership interest			46.00%	9.00%	51.60%		91.00%	0.40%
General partner units owned									2,145,096