Equity and Partners' Capital - Limited Partner and General Partner Units Table (details) (Western Gas Partners [Member])	12 Months Ended				1 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Nov. 30, 2014		Dec. 31, 2013		May 31, 2013		Jun. 30, 2012		Dec. 31, 2012
Capital Unit [Line Items]
Balance	119,717,157		106,796,483
Long-term incentive plan awards	10,403		12,648
Balance	141,192,051		119,717,157				119,717,157
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	1,156,516		699,731
December 2013 Equity Offering [Member]
Capital Unit [Line Items]
Offering	306,122		4,591,837
Texas Express And Front Range [Member]
Capital Unit [Line Items]
Acquisition	314,786
November 2014 Equity Offering [Member]
Capital Unit [Line Items]
Offering	8,773,214	[1],[2]
Common Units [Member]
Capital Unit [Line Items]
Balance	117,322,812		104,660,553
Common units issued	8,620,153				8,620,153	[1]	4,800,000	[3]	7,015,000	[4]	5,000,000
Long-term incentive plan awards	10,291		12,395
Balance	127,695,130		117,322,812				117,322,812
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	1,133,384	[5]	685,735	[6]
Common Units [Member] | December 2013 Equity Offering [Member]
Capital Unit [Line Items]
Common units issued	300,000		4,500,000
Class C Units [Member]
Capital Unit [Line Items]
Balance	0												0
Class C units issued	10,913,853
Balance	10,913,853												0
General Partner [Member]
Capital Unit [Line Items]
Balance	2,394,345		2,135,930
Offering					153,061	[1],[2]	97,959	[2],[3]	143,163	[2],[4]	102,041	[2]
Long-term incentive plan awards	112		253
Balance	2,583,068		2,394,345				2,394,345
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	23,132	[2],[5]	13,996	[2],[6]
General Partner [Member] | December 2013 Equity Offering [Member]
Capital Unit [Line Items]
Offering	6,122		91,837
General Partner [Member] | Texas Express And Front Range [Member]
Capital Unit [Line Items]
Acquisition	6,296
General Partner [Member] | November 2014 Equity Offering [Member]
Capital Unit [Line Items]
Offering	153,061

[1] Includes the issuance of 1,120,153 WES common units pursuant to the partial exercise of the underwriters’ over-allotment option. Net proceeds from this partial exercise were $77.0 million. Beginning with this partial exercise, WES WGP elected not to make a corresponding capital contribution to maintain the 2.0% general partner interest in WES. See Note 3.

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

[3] Includes the issuance of 300,000 WES common units on January 3, 2014, pursuant to the partial exercise of the underwriters’ over-allotment option. Net proceeds from this partial exercise (including WES GP’s proportionate capital contribution) were $18.1 million.

[4] Includes the issuance of 915,000 WES common units pursuant to the full exercise of the underwriters’ over-allotment option.

[5] Represents common and general partner units of WES issued during the year ended December 31, 2014, under the Continuous Offering Program. Gross proceeds generated (including WES GP’s proportionate capital contributions) during the year ended December 31, 2014, were $85.0 million. The price per unit in the table above represents an average price for all issuances under the Continuous Offering Program during the year ended December 31, 2014. As of December 31, 2014, WES had used all the capacity to issue common units under this registration statement.

[6] Represents common and general partner units of WES issued during the year ended December 31, 2013, pursuant to WES’s registration statement filed with the U.S. Securities and Exchange Commission (“SEC”) in August 2012 authorizing the issuance of up to an aggregate of $125.0 million of common units (the “Continuous Offering Program”). Gross proceeds generated (including WES GP’s proportionate capital contributions) during the year ended December 31, 2013, were $42.6 million. The price per unit in the table above represents an average price for all issuances under the Continuous Offering Program during 2013.