Equity and Partners' Capital - Equity Offerings Table (details) (Western Gas Partners [Member], USD $)	1 Months Ended		3 Months Ended		12 Months Ended		1 Months Ended
	Nov. 30, 2014		Mar. 31, 2015		Dec. 31, 2014		Apr. 30, 2015	Aug. 31, 2012	Aug. 31, 2014
Capital Unit [Line Items]
Units issued			45,711
Price per unit	$ 70.85	[1]
Underwriting discount and other offering expenses	$ 18,615,000	[1]
Net proceeds to WES	602,967,000	[1]
Table Text Block Supplement [Abstract]
General partner's interest	2.00%		1.80%
Option on Securities [Member]
Capital Unit [Line Items]
Net proceeds to WES	77,000,000
125 Million COP [Member]
Capital Unit [Line Items]
Average price per unit					$ 73.48	[2]
Underwriting discount and other offering expenses					1,738,000	[2]
Net proceeds to WES					83,245,000	[2]
Table Text Block Supplement [Abstract]
Maximum aggregate principal of common stock								125,000,000
Gross proceeds					85,000,000
500 Million COP [Member]
Capital Unit [Line Items]
Common units issued			480,109
Average price per unit			65.55	[3]
Underwriting discount and other offering expenses			396,000	[3]
Net proceeds to WES			31,076,000	[3]
Table Text Block Supplement [Abstract]
Maximum aggregate principal of common stock									500,000,000
Gross proceeds			31,500,000
Commissions paid			300,000
Common Units [Member]
Capital Unit [Line Items]
Common units issued	8,620,153	[1]
Common Units [Member] | Option on Securities [Member]
Capital Unit [Line Items]
Common units issued	1,120,153
Common Units [Member] | 125 Million COP [Member]
Capital Unit [Line Items]
Common units issued					1,133,384	[2]
Common Units [Member] | 500 Million COP [Member]
Capital Unit [Line Items]
Common units issued			480,109	[3]
Common Units [Member] | 500 Million COP [Member] | Subsequent Event [Member]
Capital Unit [Line Items]
Common units issued							289,744
General Partner [Member]
Capital Unit [Line Items]
Units issued	153,061	[1],[4]
General Partner [Member] | 125 Million COP [Member]
Capital Unit [Line Items]
Units issued					23,132	[2],[4]

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

[2] Represents common and general partner units of WES issued during the year ended December 31, 2014, pursuant to WES’s registration statement filed with the SEC in August 2012 authorizing the issuance of up to an aggregate of $125.0 million of WES common units (the “$125.0 million COP”). 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 $125.0 million COP 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.

[3] Represents common units of WES issued during the three months ended March 31, 2015, pursuant to WES’s registration statement filed with the SEC in August 2014 authorizing the issuance of up to an aggregate of $500.0 million of WES common units (the “$500.0 million COP”). Gross proceeds generated and commissions paid during the three months ended March 31, 2015, were $31.5 million and $0.3 million, respectively. The price per unit in the table above represents an average price for all issuances under the $500.0 million COP during the three months ended March 31, 2015. Does not include sales of 289,744 WES common units that settled after March 31, 2015.

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