Description of Business and Basis of Presentation - Additional Information (details) (USD $) In Millions, except Share data, unless otherwise specified			9 Months Ended			1 Months Ended	9 Months Ended			9 Months Ended				1 Months Ended			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Western Gas Partners [Member]	May 31, 2013 Western Gas Partners [Member]	Jun. 30, 2012 Western Gas Partners [Member]	Dec. 31, 2012 IPO [Member]	Sep. 30, 2012 Statement Of Cash Flow [Member]	Sep. 30, 2013 Fort Union [Member] Western Gas Partners [Member]	Sep. 30, 2013 Rendezvous [Member] Western Gas Partners [Member]	Sep. 30, 2013 Incentive Distribution Rights [Member] Western Gas Partners [Member]	Sep. 30, 2013 Non-Operated Marcellus Interest [Member] Western Gas Partners [Member]	Sep. 30, 2013 Anadarko-Operated Marcellus Interest [Member] Western Gas Partners [Member]	Sep. 30, 2013 Newcastle [Member] Western Gas Partners [Member]	Jul. 31, 2009 Chipeta Processing Limited Liability Company [Member] Western Gas Partners [Member]	Sep. 30, 2013 Chipeta Processing Limited Liability Company [Member] Western Gas Partners [Member]	Aug. 31, 2012 Chipeta Processing Limited Liability Company [Member] Western Gas Partners [Member]	Sep. 30, 2013 Anadarko Marcellus Midstream [Member] Western Gas Partners [Member]	Sep. 30, 2013 General Partner [Member] Western Gas Partners [Member]
Equity method investment ownership								14.81%	22.00%
Ownership interest			100.00%							100.00%	33.75%	33.75%	50.00%	51.00%
General partner's interest																		2.00%
Marginal percentage interest in distributions																		48.00%
Common units issued	218,895,515	218,895,515				19,758,150
Price per unit				$ 61.18	$ 43.88	$ 22.00
Proceeds from issuance initial public offering						$ 412.0
Payment for purchase of private placement						409.4
Correction of error							$ 35.7
Units issued											458,295						449,129
Ownership interest by noncontrolling owners															25.00%	24.00%