Equity and Partners' Capital - Limited Partner and General Partner Units (details) (Western Gas Partners [Member])	1 Months Ended				9 Months Ended
	May 31, 2013		Jun. 30, 2012		Sep. 30, 2013
Capital Unit [Line Items]
Balance					106,796,483
Long-term incentive plan awards					7,019
Common units issued	7,015,000	[1]	5,000,000	[1]
Balance					114,463,484
Non-Operated Marcellus Interest [Member]
Capital Unit [Line Items]
Acquisition					458,295
May 2013 Equity Offering [Member]
Capital Unit [Line Items]
Offering					7,158,163
Continuous Offering Program [Member]
Capital Unit [Line Items]
Offering					43,524
Common Units [Member]
Capital Unit [Line Items]
Balance					104,660,553
Long-term incentive plan awards					6,879
Balance					112,174,911
Common Units [Member] | Non-Operated Marcellus Interest [Member]
Capital Unit [Line Items]
Acquisition					449,129
Common Units [Member] | May 2013 Equity Offering [Member]
Capital Unit [Line Items]
Common units issued					7,015,000
Common Units [Member] | Continuous Offering Program [Member]
Capital Unit [Line Items]
Common units issued					43,350
General Partner [Member]
Capital Unit [Line Items]
Balance					2,135,930
Long-term incentive plan awards					140
Offering	143,163	[2]	102,041	[2]
Balance					2,288,573
General Partner [Member] | Non-Operated Marcellus Interest [Member]
Capital Unit [Line Items]
Acquisition					9,166
General Partner [Member] | May 2013 Equity Offering [Member]
Capital Unit [Line Items]
Offering					143,163
General Partner [Member] | Continuous Offering Program [Member]
Capital Unit [Line Items]
Offering					174

[1] Includes the issuance of 915,000 WES common units pursuant to the full exercise of the underwriters’ over-allotment option granted in connection with the May 2013 equity offering.

[2] Represents general partner units of WES issued to WES GP in exchange for WES GP’s proportionate capital contribution to maintain its 2.0% general partner interest.