Equity and Partners' Capital - Equity Offerings Table (details) (Western Gas Partners [Member], USD $)	1 Months Ended								12 Months Ended		0 Months Ended	12 Months Ended
	Nov. 30, 2014		Dec. 31, 2013		May 31, 2013		Jun. 30, 2012		Dec. 31, 2014		Jan. 03, 2014	Dec. 31, 2013		Aug. 31, 2012
Capital Unit [Line Items]
Price per unit	$ 70.85	[1]	$ 61.51	[2]	$ 61.18	[3]	$ 43.88					$ 61.51	[2]
Underwriting discount and other offering expenses	$ 18,583,000	[1]	$ 9,447,000	[2]	$ 13,203,000	[3]	$ 7,468,000					$ 9,447,000	[2]
Net proceeds to WES	602,999,000	[1]	291,827,000	[2]	424,733,000	[3]	216,409,000
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										18,100,000
Continuous Offering Program [Member]
Capital Unit [Line Items]
General partner units issued									1,156,516			699,731
Average price per unit									$ 73.48	[4]		$ 60.84	[5]
Underwriting discount and other offering expenses			965,000	[5]					1,738,000	[4]		965,000	[5]
Net proceeds to WES									83,245,000	[4]		41,603,000	[5]
Table Text Block Supplement [Abstract]
Maximum aggregate principal of common stock														125,000,000
Gross proceeds									$ 85,000,000			$ 42,600,000
Common Units [Member]
Capital Unit [Line Items]
Common units issued	8,620,153	[1]	4,800,000	[2]	7,015,000	[3]	5,000,000		8,620,153
Common Units [Member] | Option on Securities [Member]
Capital Unit [Line Items]
Common units issued	1,120,153				915,000						300,000
Common Units [Member] | Continuous Offering Program [Member]
Capital Unit [Line Items]
Common units issued									1,133,384	[4]		685,735	[5]
General Partner [Member]
Capital Unit [Line Items]
General partner units issued	153,061	[1],[6]	97,959	[2],[6]	143,163	[3],[6]	102,041	[6]
General Partner [Member] | Continuous Offering Program [Member]
Capital Unit [Line Items]
General partner units issued									23,132	[4],[6]		13,996	[5],[6]

[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] 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.

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

[4] 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.

[5] 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.

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