Equity and Partners' Capital - Additional Information (details) (USD $)	12 Months Ended		1 Months Ended									0 Months Ended	12 Months Ended			0 Months Ended
	Dec. 31, 2014		Jul. 31, 2014		Nov. 30, 2014		Dec. 31, 2013		May 31, 2013		Jun. 30, 2012	Nov. 25, 2014	Dec. 31, 2013		Dec. 31, 2012	Jan. 03, 2014
Schedule of Investments [Line Items]
Limited partner units owned	218,909,977						218,895,515						218,895,515
Anadarko [Member]
Schedule of Investments [Line Items]
Limited partner units owned	193,387,365
Ownership interest	88.30%
Anadarko [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued			5,750,000	[1]
Anadarko [Member] | Option on Securities [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued			750,000
Public [Member]
Schedule of Investments [Line Items]
Limited partner units owned	25,522,612
Ownership interest	11.70%
Western Gas Partners [Member]
Schedule of Investments [Line Items]
Ownership interest	34.90%
General partner units owned	2,583,068
General partner's interest	1.80%				2.00%
Price per unit					$ 70.85	[2]	61.51	[3]	61.18	[1]	43.88		$ 61.51	[3]
Western Gas Partners [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned	49,296,205
Common units issued	8,620,153				8,620,153	[2]	4,800,000	[3]	7,015,000	[1]	5,000,000
Western Gas Partners [Member] | Incentive Distribution Rights [Member]
Schedule of Investments [Line Items]
General partner's interest	100.00%
Western Gas Partners [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Class C units issued	10,913,853
Price per unit												$ 68.72
Proceeds from the issuance of WES Class C units	750,000,000											$ 750,000,000	$ 0		$ 0
Western Gas Partners [Member] | Option on Securities [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Common units issued					1,120,153				915,000							300,000
Western Gas Partners [Member] | Anadarko [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned	10,913,853
Western Gas Partners [Member] | Public [Member]
Schedule of Investments [Line Items]
Ownership interest	55.00%
Western Gas Partners [Member] | Public [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned	77,641,306
Western Gas Partners [Member] | Other Subsidiaries Of Anadarko [Member]
Schedule of Investments [Line Items]
Ownership interest	8.30%
Western Gas Partners [Member] | Other Subsidiaries Of Anadarko [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned	757,619
Western Gas Partners [Member] | Other Subsidiaries Of Anadarko [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Class C units issued	10,913,853	[4]			10,913,853
Maximum [Member] | Western Gas Partners [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Redeemable option on units					$ 150,000,000

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

[2] 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.

[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] WES acquired Nuevo Midstream, LLC (“Nuevo”) from a third party. Following the acquisition, WES changed the name of Nuevo to Delaware Basin Midstream, LLC (“DBM”). The assets acquired include cryogenic processing plants, a gas gathering system, and related facilities and equipment, which serve production from Reeves, Loving and Culberson Counties, Texas and Eddy and Lea Counties, New Mexico. These assets are referred to collectively as the “DBM complex.” See Note 4 for a discussion of the WES Class C units.