Transactions with Affiliates - Summary Table (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Related Party Transaction [Line Items]
Revenues and other		$ 385,101	$ 357,521	[1]	$ 1,190,082		$ 1,016,151	[1]
Equity income, net	[2],[3]	21,976	19,063	[1]	59,137	[4]	41,322	[1],[4]
Cost of product	[5]	127,721	113,217	[1]	414,378		330,926	[1]
Operation and maintenance	[5]	80,633	67,489	[1]	218,640		184,023	[1]
General and administrative	[5]	10,059	9,116	[1]	30,848		28,193	[1]
Operating expenses		289,265	243,892	[1]	1,149,489		699,152	[1]
Interest income	[6]	4,225	4,225	[1]	12,675		12,675	[1]
Interest expense	[7]	31,773	20,878	[1]	82,339		55,703	[1]
Distributions to unitholders					223,016		164,725	[1]
Affiliates [Member]
Related Party Transaction [Line Items]
Revenues and other	[3]	247,458	269,632	[1]	777,739		769,331	[1]
Cost of product	[3]	35,673	27,034		132,663		85,071
Operation and maintenance	[8]	17,662	15,583		50,534		44,961
General and administrative	[9]	7,875	7,214		23,154		21,786
Operating expenses		61,210	49,831		206,351		151,818
Interest expense	[10]	4,310	0		9,922		0
Affiliates [Member] | Western Gas Equity Partners, LP [Member]
Related Party Transaction [Line Items]
Distributions to unitholders	[11]	69,508	52,456		196,177		148,291
Affiliates [Member] | Western Gas Partners, LP [Member]
Related Party Transaction [Line Items]
Distributions to unitholders	[12]	$ 568	$ 492		$ 1,648		$ 1,235

[1] Financial information has been recast to include the financial position and results attributable to the DBJV system. See Note 1 and Note 2.

[2] Income earned from equity investments is classified as affiliate. See Note 1.

[3] Represents amounts earned or incurred on and subsequent to the date of acquisition of WES assets, as well as amounts earned or incurred by Anadarko on a historical basis related to WES assets prior to the acquisition of such assets by WES, recognized under gathering, treating or processing agreements, and purchase and sale agreements. See Adjustments to Previously Issued Financial Statements in Note 1.

[4] Income earned on, distributions from and contributions to equity investments are classified as affiliate. See Note 1.

[5] Cost of product includes product purchases from Anadarko (as defined in Note 1) of $35.7 million and $132.7 million for the three and nine months ended September 30, 2015, respectively, and $27.0 million and $85.1 million for the three and nine months ended September 30, 2014, respectively. Operation and maintenance includes charges from Anadarko of $17.7 million and $50.5 million for the three and nine months ended September 30, 2015, respectively, and $15.6 million and $45.0 million for the three and nine months ended September 30, 2014, respectively. General and administrative includes charges from Anadarko of $7.9 million and $23.2 million for the three and nine months ended September 30, 2015, respectively, and $7.2 million and $21.8 million for the three and nine months ended September 30, 2014, respectively. See Note 5.

[6] Represents interest income recognized on the note receivable from Anadarko.

[7] Includes affiliate (as defined in Note 1) interest expense of $4.3 million and $9.9 million for the three and nine months ended September 30, 2015, respectively, and zero for each of the three and nine months ended September 30, 2014. See Note 2 and Note 9.

[8] Represents expenses incurred on and subsequent to the date of the acquisition of WES assets, as well as expenses incurred by Anadarko on a historical basis related to WES assets prior to the acquisition of such assets by WES.

[9] Represents general and administrative expense incurred on and subsequent to the date of WES’s acquisition of WES assets, as well as a management services fee for reimbursement of expenses incurred by Anadarko for periods prior to the acquisition of WES assets by WES. These amounts include equity-based compensation expense allocated to WES and WGP by Anadarko (see WES LTIP and WGP LTIP and Anadarko Incentive Plans within this Note 5) and amounts charged by Anadarko under the WGP omnibus agreement.

[10] For the three and nine months ended September 30, 2015, includes WES’s accretion expense recognized on the Deferred purchase price obligation - Anadarko for the acquisition of DBJV (see Note 2 and Note 9) and for the nine months ended September 30, 2015, includes interest expense recognized on the WGP working capital facility (see Note 9).

[11] Represents distributions paid under WGP’s partnership agreement (see Note 3 and Note 4).

[12] Represents distributions paid to other subsidiaries of Anadarko under WES’s partnership agreement (see Note 3 and Note 4).