Equity and Partners' Capital - Equity Offerings Table (details) (USD $)	1 Months Ended							9 Months Ended	0 Months Ended	1 Months Ended				0 Months Ended	1 Months Ended					9 Months Ended		12 Months Ended			9 Months Ended		12 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2014 Common Units [Member]		Jul. 31, 2014 Common Units [Member] Option on Securities [Member]	Dec. 31, 2013 Western Gas Partners [Member]		May 31, 2013 Western Gas Partners [Member]		Sep. 30, 2014 Western Gas Partners [Member]	Jan. 03, 2014 Western Gas Partners [Member] Option on Securities [Member]	Dec. 31, 2013 Western Gas Partners [Member] Common Units [Member]		May 31, 2013 Western Gas Partners [Member] Common Units [Member]		Jan. 03, 2014 Western Gas Partners [Member] Common Units [Member] Option on Securities [Member]	May 31, 2013 Western Gas Partners [Member] Common Units [Member] Option on Securities [Member]	Dec. 31, 2013 Western Gas Partners [Member] General Partner [Member]		May 31, 2013 Western Gas Partners [Member] General Partner [Member]		Sep. 30, 2014 Western Gas Partners [Member] Continuous Offering Program [Member]		Dec. 31, 2013 Western Gas Partners [Member] Continuous Offering Program [Member]		Aug. 31, 2012 Western Gas Partners [Member] Continuous Offering Program [Member]	Sep. 30, 2014 Western Gas Partners [Member] Continuous Offering Program [Member] Common Units [Member]		Dec. 31, 2013 Western Gas Partners [Member] Continuous Offering Program [Member] Common Units [Member]		Sep. 30, 2014 Western Gas Partners [Member] Continuous Offering Program [Member] General Partner [Member]		Dec. 31, 2013 Western Gas Partners [Member] Continuous Offering Program [Member] General Partner [Member]
Capital Unit [Line Items]
Common units issued	5,750,000	[1]	750,000							4,800,000	[2]	7,015,000	[1]	300,000	915,000										1,133,384	[3]	685,735	[4]
General partner units issued																97,959	[2],[5]	143,163	[1],[5]	1,156,516									23,132	[3],[5]	13,996	[4],[5]
Price per unit				$ 61.51	[2]	$ 61.18	[1]
Average price per unit																				$ 73.48	[3]	$ 60.84	[4]
Underwriting discount and other offering expenses				$ 9,447,000	[2]	$ 13,203,000	[1]													$ 1,726,000	[3]	$ 965,000	[4]
Net proceeds to WES				291,827,000	[2]	424,733,000	[1]		18,100,000											83,257,000	[3]	41,603,000	[4]
Table Text Block Supplement [Abstract]
General partner's interest								2.00%
Maximum aggregate principal of common stock																								125,000,000
Gross proceeds																				$ 85,000,000		$ 42,600,000

[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] Includes the issuance of 300,000 WES common units on January 3, 2014, pursuant to the partial exercise of the underwriters’ over-allotment option granted in connection with the December 2013 equity offering. Net proceeds from this partial exercise (including WES GP’s proportionate capital contribution) were $18.1 million.

[3] Represents common and general partner units of WES issued during the nine months ended September 30, 2014, under the Continuous Offering Program. Gross proceeds generated (including WES GP’s proportionate capital contributions) 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 nine months ended September 30, 2014. As of September 30, 2014, WES had used all the capacity to issue common units under this registration statement.

[4] 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 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.

[5] 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 in WES.