Western Midstream Partners (WES) 10-Q 31 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 29, 2018
Document And Entity Information [Abstract]
Trading Symbol	WGP
Entity Registrant Name	Western Gas Equity Partners, LP
Entity Central Index Key	1,423,902
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Units Outstanding		218,937,797
Entity Emerging Growth Company	false
Entity Small Business	false

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Revenues and Other
Revenues and other		$ 507,762	$ 574,695	$ 1,432,483		$ 1,616,338
Equity income, net – affiliates	[1]	43,110	21,519	102,752		62,708
Operating expenses
Cost of product	[2]	105,966	239,223	303,518		631,859
Operation and maintenance	[2]	111,359	79,536	300,266		229,444
General and administrative	[2]	15,158	12,922	44,853		37,595
Property and other taxes		10,954	11,215	35,090		35,433
Depreciation and amortization		82,553	72,539	238,187		216,272
Impairments		25,317	2,159	152,708		170,079
Total operating expenses		351,307	417,594	1,074,622		1,320,682
Gain (loss) on divestiture and other, net	[3]	65	72	351	[4]	135,017	[4]
Proceeds from business interruption insurance claims		0	0	0		29,882
Operating income (loss)		199,630	178,692	460,964		523,263
Interest income – affiliates	[5]	4,225	4,225	12,675		12,675
Interest expense		(48,316)	(36,117)	(133,359)		(108,447)
Other income (expense), net		655	311	2,749		1,029
Income (loss) before income taxes		156,194	147,111	343,029		428,520
Income tax (benefit) expense		1,517	510	3,301		4,905
Net income (loss)		154,677	146,601	339,728		423,615
Net income (loss) attributable to noncontrolling interests		47,203	50,399	63,669		146,529
Net income (loss) attributable to Western Gas Equity Partners, LP		107,474	96,202	276,059		277,086
Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		409,106		1,146,099
Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		22,735		67,433
Product Sales [Member]
Revenues and Other
Revenues and other		75,150		217,738
Affiliates [Member]
Revenues and Other
Revenues and other	[1]	274,514	351,127	766,179		982,595
Operating expenses
Cost of product	[1]	46,971	22,902	131,428		60,497
Operation and maintenance	[6]	25,145	18,110	68,830		53,661
General and administrative	[7]	11,780	10,414	35,000		29,637
Total operating expenses		83,896	51,426	235,258		143,795
Interest expense	[8]	0	0	0		(71)
Affiliates [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		204,090	157,303	582,579		484,601
Affiliates [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		701	0	1,228		0
Affiliates [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		69,723	185,002	182,372		489,172
Affiliates [Member] | Other [Member]
Revenues and Other
Revenues and other		0	8,822	0		8,822
Third Parties [Member]
Revenues and Other
Revenues and other		233,248	223,568	666,304		633,743
Operating expenses
Interest expense		(48,316)	(36,117)	(133,359)		(108,376)
Third Parties [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		205,016	148,884	563,520		428,835
Third Parties [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		22,034	0	66,205		0
Third Parties [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		5,427	74,139	35,366		201,318
Third Parties [Member] | Other [Member]
Revenues and Other
Revenues and other		$ 771	$ 545	$ 1,213		$ 3,590
Limited Partner [Member]
Limited partners' interest in net income (loss):
Net income (loss) per common unit - basic and diluted		$ 0.49	$ 0.44	$ 1.26		$ 1.27
Weighted-average common units outstanding - basic and diluted		218,938	218,933	218,935		218,931
[1]	Represents amounts earned or incurred on and subsequent to the date of the 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.
[2]	Cost of product includes product purchases from affiliates (as defined in Note 1) of $47.0 million and $131.4 million for the three and nine months ended September 30, 2018, respectively, and $22.9 million and $60.5 million for the three and nine months ended September 30, 2017, respectively. Operation and maintenance includes charges from affiliates of $25.1 million and $68.8 million for the three and nine months ended September 30, 2018, respectively, and $18.1 million and $53.7 million for the three and nine months ended September 30, 2017, respectively. General and administrative includes charges from affiliates of $11.8 million and $35.0 million for the three and nine months ended September 30, 2018, respectively, and $10.4 million and $29.6 million for the three and nine months ended September 30, 2017, respectively. See Note 6.
[3]	Includes losses related to an incident at the DBM complex for the nine months ended September 30, 2017. See Note 1.
[4]	Includes losses related to an incident at the DBM complex for the nine months ended September 30, 2017. See Note 1.
[5]	Represents interest income recognized on the note receivable from Anadarko.
[6]	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.
[7]	Represents general and administrative expense incurred on and subsequent to the date of the 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 Anadarko Incentive Plan within this Note 6) and amounts charged by Anadarko under the WGP and WES omnibus agreements.
[8]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Cost of product	[1]	$ 105,966	$ 239,223	$ 303,518	$ 631,859
Operation and maintenance	[1]	111,359	79,536	300,266	229,444
General and administrative	[1]	15,158	12,922	44,853	37,595
Affiliates [Member]
Cost of product	[2]	46,971	22,902	131,428	60,497
Operation and maintenance	[3]	25,145	18,110	68,830	53,661
General and administrative	[4]	$ 11,780	$ 10,414	$ 35,000	$ 29,637
[1]	Cost of product includes product purchases from affiliates (as defined in Note 1) of $47.0 million and $131.4 million for the three and nine months ended September 30, 2018, respectively, and $22.9 million and $60.5 million for the three and nine months ended September 30, 2017, respectively. Operation and maintenance includes charges from affiliates of $25.1 million and $68.8 million for the three and nine months ended September 30, 2018, respectively, and $18.1 million and $53.7 million for the three and nine months ended September 30, 2017, respectively. General and administrative includes charges from affiliates of $11.8 million and $35.0 million for the three and nine months ended September 30, 2018, respectively, and $10.4 million and $29.6 million for the three and nine months ended September 30, 2017, respectively. See Note 6.
[2]	Represents amounts earned or incurred on and subsequent to the date of the 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.
[3]	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.
[4]	Represents general and administrative expense incurred on and subsequent to the date of the 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 Anadarko Incentive Plan within this Note 6) and amounts charged by Anadarko under the WGP and WES omnibus agreements.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents		$ 132,877	$ 79,588
Accounts receivable, net	[1]	224,887	160,239
Other current assets	[2]	26,119	15,383
Total current assets		383,883	255,210
Note receivable - Anadarko		260,000	260,000
Property, plant and equipment
Cost		8,912,755	7,864,535
Less accumulated depreciation		2,494,121	2,133,644
Net property, plant and equipment		6,418,634	5,730,891
Goodwill		416,160	416,160
Other intangible assets		753,947	775,269
Equity investments		786,876	566,211
Other assets		14,057	12,570
Total assets		9,033,557	8,016,311
Current liabilities
Accounts and imbalance payables		360,651	349,801
Short-term debt		28,000	0
Accrued ad valorem taxes		37,123	26,633
Accrued liabilities	[3]	114,504	47,992
Total current liabilities		540,278	424,426
Long-term liabilities
Long-term debt		4,566,464	3,492,712
Deferred income taxes		10,285	7,409
Asset retirement obligations		157,933	143,394
Other liabilities	[4]	141,957	3,491
Total long-term liabilities		4,876,639	3,647,006
Total liabilities		5,416,917	4,071,432
Equity and partners' capital
Common units (218,937,797 and 218,933,141 units issued and outstanding at September 30, 2018, and December 31, 2017, respectively)		981,408	1,061,125
Total partners' capital		981,408	1,061,125
Noncontrolling interests		2,635,232	2,883,754
Total equity and partners' capital		3,616,640	3,944,879
Total liabilities, equity and partners' capital		$ 9,033,557	$ 8,016,311
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $59.1 million and $36.1 million as of September 30, 2018, and December 31, 2017, respectively.
[2]	Other current assets includes affiliate amounts of $1.4 million and zero as of September 30, 2018, and December 31, 2017, respectively.
[3]	Accrued liabilities includes affiliate amounts of $2.3 million and $0.2 million as of September 30, 2018, and December 31, 2017, respectively.
[4]	Other liabilities includes affiliate amounts of $50.2 million and $0.7 million as of September 30, 2018, and December 31, 2017, respectively.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Common units issued		218,937,797	218,933,141
Common units outstanding		218,937,797	218,933,141
Accounts receivable, net	[1]	$ 224,887	$ 160,239
Other current assets	[2]	26,119	15,383
Accrued liabilities	[3]	114,504	47,992
Other liabilities	[4]	141,957	3,491
Affiliates [Member]
Accounts receivable, net		59,100	36,100
Other current assets		1,400	0
Accrued liabilities		2,300	200
Other liabilities		$ 50,200	$ 700
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $59.1 million and $36.1 million as of September 30, 2018, and December 31, 2017, respectively.
[2]	Other current assets includes affiliate amounts of $1.4 million and zero as of September 30, 2018, and December 31, 2017, respectively.
[3]	Accrued liabilities includes affiliate amounts of $2.3 million and $0.2 million as of September 30, 2018, and December 31, 2017, respectively.
[4]	Other liabilities includes affiliate amounts of $50.2 million and $0.7 million as of September 30, 2018, and December 31, 2017, respectively.

Consolidated Statement of Equit

Consolidated Statement of Equity and Partners' Capital - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands		Total	Western Gas Partners, LP [Member]	Chipeta [Member]	Common Units [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member]Western Gas Partners, LP [Member]	Noncontrolling Interests [Member]Chipeta [Member]
Balance at Dec. 31, 2017		$ 3,944,879			$ 1,061,125	$ 2,883,754
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		339,728			276,059	63,669
Above-market component of swap agreements with Anadarko	[1]	40,722			40,722
WES equity transactions, net	[2]	0			(14,565)	14,565
Distributions to noncontrolling interest owners			$ (287,435)	$ (9,446)			$ (287,435)	$ (9,446)
Distributions to WGP unitholders		(372,189)			(372,189)
Contributions of equity-based compensation to WES by Anadarko		4,306			4,306
Other		454			150	304
Balance at Sep. 30, 2018		3,616,640			981,408	2,635,232
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect of accounting change	[3]	$ (44,379)			$ (14,200)	$ (30,179)
[1]	See Note 6.
[2]	Includes the impact of the cumulative effect of accounting change in WES’s consolidated statement of equity and partners’ capital. The $14.6 million decrease to partners’ capital, together with net income (loss) attributable to Western Gas Equity Partners, LP, totaled $261.5 million for the nine months ended September 30, 2018.
[3]	See Note 1.

Consolidated Statement of Equ_2

Consolidated Statement of Equity and Partners' Capital (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
WES equity transactions, net	$ 0	[1]
Combined change in Partners' Capital from WES equity transactions, net and net income (loss) attributable to Western Gas Equity Partners, LP	261,500
Common Units [Member]
WES equity transactions, net	$ (14,565)	[1]
[1]	Includes the impact of the cumulative effect of accounting change in WES’s consolidated statement of equity and partners’ capital. The $14.6 million decrease to partners’ capital, together with net income (loss) attributable to Western Gas Equity Partners, LP, totaled $261.5 million for the nine months ended September 30, 2018.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017
Cash flows from operating activities
Net income (loss)		$ 339,728		$ 423,615
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		238,187		216,272
Impairments		152,708		170,079
Non-cash equity-based compensation expense		4,834		3,751
Deferred income taxes		3,054		3,882
Accretion and amortization of long-term obligations, net		4,659		3,701
Equity income, net – affiliates	[1]	(102,752)		(62,708)
Distributions from equity investment earnings – affiliates		93,827		64,313
(Gain) loss on divestiture and other, net	[2],[3]	(351)		(135,017)
Lower of cost or market inventory adjustments		184		140
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		(64,690)		(47,137)
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		55,480		4,127
Change in other items, net		24,511		(2,549)
Net cash provided by operating activities		749,379		642,469
Cash flows from investing activities
Capital expenditures		(949,022)		(419,193)
Investments in equity affiliates		(67,979)		(384)
Distributions from equity investments in excess of cumulative earnings – affiliates		18,097	[4]	16,255
Proceeds from property insurance claims		0		22,977
Net cash used in investing activities		(1,160,684)		(514,797)
Cash flows from financing activities
Borrowings, net of debt issuance costs		2,135,629		249,989
Repayments of debt		(1,040,000)		0
Increase (decrease) in outstanding checks		(2,687)		3,310
Distributions to WGP unitholders	[5]	(372,189)		(324,290)
Net contributions from (distributions to) Anadarko		0		30
Above-market component of swap agreements with Anadarko	[5]	40,722		46,719
Net cash provided by (used in) financing activities		464,594		(333,708)
Net increase (decrease) in cash and cash equivalents		53,289		(206,036)
Cash and cash equivalents at beginning of period		79,588		359,072
Cash and cash equivalents at end of period		132,877		153,036
Supplemental disclosures
Accretion expense and revisions to the Deferred purchase price obligation – Anadarko		0		(4,094)
Net distributions to (contributions from) Anadarko of other assets		0		(1,373)
Interest paid, net of capitalized interest		114,790		98,956
Taxes paid (reimbursements received)		(87)		189
Accrued capital expenditures		178,694		165,732
Fair value of properties and equipment from non-cash third party transactions	[6]	0		551,453
Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(9,446)		(9,049)
Western Gas Partners, LP [Member]
Cash flows from financing activities
Proceeds from the issuance of WES common units, net of offering expenses		0		(183)
Distributions to noncontrolling interest owners of WES		(287,435)		(262,888)
Affiliates [Member]
Cash flows from investing activities
Contributions in aid of construction costs from affiliates		0		1,386
Acquisitions		(254)		(3,910)
Cash flows from financing activities
Settlement of the Deferred purchase price obligation - Anadarko	[6]	0		(37,346)
Distributions to WGP unitholders	[7]	(298,818)		(264,533)
Affiliates [Member] | Western Gas Partners, LP [Member]
Cash flows from financing activities
Distributions to WGP unitholders	[8]	(5,642)		(5,280)
Supplemental disclosures
Net distributions to (contributions from) Anadarko of other assets		0		(1,373)
Third Parties [Member]
Cash flows from investing activities
Acquisitions		(161,858)		(155,298)
Proceeds from the sale of assets		$ 332		$ 23,370
[1]	Represents amounts earned or incurred on and subsequent to the date of the 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.
[2]	Includes losses related to an incident at the DBM complex for the nine months ended September 30, 2017. See Note 1.
[3]	Includes losses related to an incident at the DBM complex for the nine months ended September 30, 2017. See Note 1.
[4]	Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, are calculated on an individual investment basis.
[5]	See Note 6.
[6]	See Note 3.
[7]	Represents distributions paid under WGP’s partnership agreement (see Note 4 and Note 5).
[8]	Represents distributions paid to other subsidiaries of Anadarko under WES’s partnership agreement (see Note 4 and Note 5).

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION General. Western Gas Equity Partners, LP is a Delaware master limited partnership (“MLP”) formed in September 2012 to own three types of partnership interests in Western Gas Partners, LP. Western Gas Equity Partners, LP was formed by converting WGR Holdings, LLC into a limited partnership and changing its name. Western Gas Partners, LP (together with its subsidiaries, “WES”) is a Delaware MLP formed by Anadarko Petroleum Corporation in 2007 to acquire, own, develop and operate midstream assets. For purposes of these consolidated financial statements, “WGP” refers to Western Gas Equity Partners, LP in its individual capacity or to Western Gas Equity Partners, LP and its subsidiaries, including Western Gas Holdings, LLC and WES, as the context requires. “WES GP” refers to Western Gas Holdings, LLC, individually as the general partner of WES, and excludes WES. WGP’s general partner, Western Gas Equity Holdings, LLC (“WGP GP”), is a wholly owned subsidiary of Anadarko Petroleum Corporation. WES GP owns all of the general partner interest in WES, which constitutes substantially all of its business, which primarily is to manage the affairs and operations of WES. Refer to Note 5 for a discussion of WGP’s holdings of WES equity. “Anadarko” refers to Anadarko Petroleum Corporation and its subsidiaries, excluding WGP and WGP GP, and “affiliates” refers to subsidiaries of Anadarko, excluding WGP, but including equity interests in Fort Union Gas Gathering, LLC (“Fort Union”), White Cliffs Pipeline, LLC (“White Cliffs”), Rendezvous Gas Services, LLC (“Rendezvous”), Enterprise EF78 LLC (the “Mont Belvieu JV”), Texas Express Pipeline LLC (“TEP”), Texas Express Gathering LLC (“TEG”), Front Range Pipeline LLC (“FRP”), Whitethorn Pipeline Company LLC (“Whitethorn LLC”) and Cactus II Pipeline LLC (“Cactus II”). See Note 3 . The interests in TEP, TEG and FRP are referred to collectively as the “TEFR Interests.” “MGR assets” refers to the Red Desert complex and the Granger straddle plant. WES is engaged in the business of gathering, compressing, treating, processing and transporting natural gas; gathering, stabilizing and transporting condensate, natural gas liquids (“NGLs”) and crude oil; and gathering and disposing of produced water. In addition, in its capacity as a processor of natural gas, WES also buys and sells natural gas, NGLs and condensate on behalf of itself and as agent for its customers under certain of its contracts. WES provides these midstream services for Anadarko, as well as for third-party producers and customers. As of September 30, 2018 , WES’s assets and investments consisted of the following: Owned and Operated Operated Interests Non-Operated Interests Equity Interests Gathering systems (1) 12 3 3 2 Treating facilities 19 3 — 3 Natural gas processing plants/trains 20 4 — 2 NGL pipelines 2 — — 3 Natural gas pipelines 5 — — — Oil pipelines — 1 — 2 (1) Includes the DBM water systems. These assets and investments are located in the Rocky Mountains (Colorado, Utah and Wyoming), North-central Pennsylvania, Texas and New Mexico. Mentone Train I, a processing train that is part of the DBM complex, is expected to commence operation in the fourth quarter of 2018. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Basis of presentation. The following table outlines WES’s ownership interests and the accounting method of consolidation used in WES’s consolidated financial statements for entities not wholly owned: Percentage Interest Equity investments (1) Fort Union 14.81 % White Cliffs 10 % Rendezvous 22 % Mont Belvieu JV 25 % TEP 20 % TEG 20 % FRP 33.33 % Whitethorn 20 % Cactus II 15 % Proportionate consolidation (2) Marcellus Interest systems 33.75 % Newcastle system 50 % Springfield system 50.1 % Full consolidation Chipeta (3) 75 % (1) Investments in non-controlled entities over which WES exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to WES’s share of average throughput for these investments. (2) WGP proportionately consolidates WES’s associated share of the assets, liabilities, revenues and expenses attributable to these assets. (3) The 25% interest in Chipeta Processing LLC (“Chipeta”) held by a third-party member is reflected within noncontrolling interests in the consolidated financial statements, in addition to the noncontrolling interests noted below. The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). The consolidated financial statements include the accounts of WGP and entities in which it holds a controlling financial interest, including WES and WES GP. All significant intercompany transactions have been eliminated. Certain information and note disclosures commonly included in annual financial statements have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, the accompanying consolidated financial statements and notes should be read in conjunction with WGP’s 2017 Form 10-K, as filed with the SEC on February 16, 2018 . Management believes that the disclosures made are adequate to make the information not misleading. The consolidated financial results of WES are included in WGP’s consolidated financial statements due to WGP’s 100% ownership interest in WES GP and WES GP’s control of WES. Throughout these notes to consolidated financial statements, and to the extent material, any differences between the consolidated financial results of WGP and WES are discussed separately. WGP has no independent operations or material assets other than its partnership interests in WES. WGP’s consolidated financial statements differ from those of WES primarily as a result of (i) the presentation of noncontrolling interest ownership (attributable to the limited partner interests in WES held by the public, other subsidiaries of Anadarko and private investors, see Note 5 ), (ii) the elimination of WES GP’s investment in WES with WES GP’s underlying capital account, (iii) the general and administrative expenses incurred by WGP, which are separate from, and in addition to, those incurred by WES, (iv) the inclusion of the impact of WGP equity balances and WGP distributions, and (v) WGP’s senior secured revolving credit facility (“WGP RCF”). See Note 10 . 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Adjustments to previously issued financial statements. WGP’s unaudited consolidated statements of operations for the nine months ended September 30, 2018, include adjustments to revenue and cost of product expense of the following amounts: (i) $39.0 million increase in Service revenues - fee based, (ii) $12.6 million increase in Product sales and (iii) $51.6 million increase in Cost of product; all of which relate to the six months ended June 30, 2018. During the third quarter of 2018, management determined that under ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) adopted on January 1, 2018, WES’s marketing affiliate was acting as WES’s agent in certain product sales transactions on behalf of WES and in performing marketing services on behalf of WES’s customers. The adjustments have no impact to Operating income (loss), Net income (loss), the balance sheets, cash flows or any non-GAAP metric WES uses to evaluate its operations (see Key Performance Metrics under Item 2 of this Form 10-Q) and are not considered material to the results of operations for the nine months ended September 30, 2018. WGP will revise its previously reported unaudited financial statements for 2018 interim periods to reflect the adjustments in future filings. Variable interest entity. WES is a variable interest entity (“VIE”) because the partners in WES with equity at risk lack the power, through voting or similar rights, to direct the activities that most significantly impact WES’s economic performance. A reporting entity that concludes it has a variable interest in a VIE must evaluate whether it has a controlling financial interest in the VIE, such that it is the VIE’s primary beneficiary and should consolidate. WGP is the primary beneficiary of WES and therefore should consolidate because (i) WGP has the power to direct the activities of WES that most significantly affect its economic performance and (ii) WGP has the right to receive benefits or the obligation to absorb losses that could be potentially significant to WES. As noted above, WGP has no independent operations or material assets other than its partnership interests in WES. The assets of WES cannot be used by WGP for general partnership purposes. WES’s long-term debt is recourse to WES GP, which is wholly owned by WGP. In turn, WES GP is indemnified by wholly owned subsidiaries of Anadarko for any claims made against WES GP under the indentures governing WES’s outstanding notes or borrowings under WES’s senior unsecured revolving credit facility (“WES RCF”). WES’s sources of liquidity include cash and cash equivalents, cash flows generated from operations, interest income on its $260.0 million note receivable from Anadarko, available borrowing capacity under the WES RCF, and issuances of additional equity or debt securities. Noncontrolling interests. WGP’s noncontrolling interests in the consolidated financial statements consist of the following for all periods presented: (i) the 25% interest in Chipeta held by a third-party member, (ii) the publicly held limited partner interests in WES, (iii) the 2,011,380 WES common units issued by WES to other subsidiaries of Anadarko as part of the consideration paid for the acquisitions of the Non-Operated Marcellus Interest, the TEFR Interests and Springfield Pipeline LLC (“Springfield”), and (iv) the WES Class C units issued by WES to a subsidiary of Anadarko as part of the funding for the acquisition of Delaware Basin Midstream, LLC (“DBM”). The WES Series A Preferred units issued to private investors as part of the funding of the Springfield acquisition were also noncontrolling interests in the consolidated financial statements until converted into WES common units in 2017. See Note 3 and Note 5 . When WES issues equity, the carrying amount of the noncontrolling interest reported by WGP is adjusted to reflect the noncontrolling ownership interest in WES. The resulting impact of such noncontrolling interest adjustment on WGP’s interest in WES is reflected as an adjustment to WGP’s partners’ capital. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Presentation of WES assets. The term “WES assets” includes both the assets indirectly owned and the interests accounted for under the equity method by WGP through its partnership interests in WES as of September 30, 2018 (see Note 8 ). Because WGP owns the entire interest in and controls WES GP, and WGP GP is controlled by Anadarko, each of WES’s acquisitions of WES assets from Anadarko has been considered a transfer of net assets between entities under common control. As such, WES assets acquired from Anadarko were initially recorded at Anadarko’s historic carrying value, which did not correlate to the total acquisition price paid by WES. Further, after an acquisition of WES assets from Anadarko, WES and WGP (by virtue of its consolidation of WES) may be required to recast their financial statements to include the activities of such WES assets from the date of common control. For those periods requiring recast, the consolidated financial statements for periods prior to the acquisition of WES assets from Anadarko are prepared from Anadarko’s historical cost-basis accounts and may not necessarily be indicative of the actual results of operations that would have occurred if WES had owned the WES assets during the periods reported. Net income (loss) attributable to the WES assets acquired from Anadarko for periods prior to WES’s acquisition of the WES assets is not allocated to the limited partners. Use of estimates. In preparing financial statements in accordance with GAAP, management makes informed judgments and estimates that affect the reported amounts of assets, liabilities, revenues and expenses. Management evaluates its estimates and related assumptions regularly, using historical experience and other methods considered reasonable. Changes in facts and circumstances or additional information may result in revised estimates and actual results may differ from these estimates. Effects on the business, financial condition and results of operations resulting from revisions to estimates are recognized when the facts that give rise to the revisions become known. The information included herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the consolidated financial statements, and certain prior-period amounts have been reclassified to conform to the current-year presentation. Shutdown of gathering systems. In May 2018, after assessing a number of factors, with safety and protection of the environment as the primary focus, WES decided to take the Kitty Draw gathering system in Wyoming (part of the Hilight system) and the Third Creek gathering system in Colorado (part of the DJ Basin complex) permanently out of service. Results for the three and nine months ended September 30, 2018 , reflect (i) accruals of zero and $10.9 million , respectively, in anticipated costs associated with the shutdown of the systems, recorded as a reduction in affiliate Product sales in the consolidated statements of operations and (ii) impairment expense of $6.8 million and $134.0 million , respectively, associated with reducing the net book value of the gathering systems and increasing the asset retirement obligation. Insurance recoveries. In December 2015, there was an initial fire and secondary explosion at the processing facility within the DBM complex. The majority of the damage from the incident was to the liquid handling facilities and the amine treating units at the inlet of the complex. During the nine months ended September 30, 2017 , a $5.7 million loss was recorded in Gain (loss) on divestiture and other, net in the consolidated statements of operations, related to a change in WES’s estimate of the amount that would be recovered under the property insurance claim based on further discussions with insurers. During the second quarter of 2017, WES reached a settlement with insurers and final proceeds were received. During the nine months ended September 30, 2017 , WES received $52.9 million in cash proceeds from insurers, including $29.9 million in proceeds from business interruption insurance claims and $23.0 million in proceeds from property insurance claims. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Recently adopted accounting standards. Accounting Standards Update (“ASU”) 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash requires an entity to explain the changes in the total of cash, cash equivalents, restricted cash, and restricted cash equivalents on the statement of cash flows and to provide a reconciliation of the totals in that statement to the related captions in the balance sheet when the cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet. WGP adopted this ASU using a retrospective approach on January 1, 2018, and the adoption did not impact the consolidated financial statements. Revenue from contracts with customers (Topic 606). WGP adopted Topic 606 on January 1, 2018, using the modified retrospective method applied to WES contracts that were not completed as of January 1, 2018. The cumulative effect adjustment that was recognized in the opening balance of equity and partners’ capital was a decrease of $44.4 million . The comparative historical financial information has not been adjusted and continues to be reported under Revenue Recognition (Topic 605) (“Topic 605”). Effective January 1, 2018, WGP changed its accounting policy for revenue recognition as detailed below: • Fee-based gathering / processing. Under Topic 605, fee revenues were recognized based on the rate in effect for the month of service, even when certain fees were charged on an upfront or limited-term basis. In addition, deficiency fees were charged and recognized only when the customer did not meet the specified delivery minimums for the completed performance period. Under Topic 606, (i) revenues continue to be recognized based on the rate in effect when the fee is either the same rate per unit over the contract term or when the fee escalates and the escalation factor approximates inflation, (ii) deficiency fees are estimated and recognized during the performance period as the services are performed for the customer’s delivered volumes, and (iii) timing differences between Service revenues – fee based recognized and amounts billed to customers are recognized as contract assets or contract liabilities, as appropriate, which results in a change in the timing of revenue and changes to net income as a result of the revenue contract’s consideration provisions. In addition, under Topic 606, revenue associated with upfront or limited-term fees is recognized over the expected period of customer benefit, which is generally the life of the related properties. These revenues also include revenues earned for marketing services performed on behalf of WES’s customers, and the expense associated with these marketing activities is recognized in cost of product expense, resulting in no impact to operating income. • Cost of service rate adjustments. Under Topic 605, revenue was recognized based on the amounts billed to customers each period as Service revenues – fee based. Under Topic 606, fixed minimum volume commitment demand fees and variable fees that are also billed on these minimum volumes are recognized as Service revenues – fee based on a consistent per-unit rate over the term of the contract. Annual adjustments are made to the cost of service rates charged to customers, and, as a result, a cumulative catch-up revenue adjustment related to the services already provided under the contract may be recorded in future periods, with revenues for the remaining term of the contract recognized on a consistent per-unit rate. Fees received on volumes in excess of the minimum volumes are recognized as Service revenues – fee based as service is provided to the customer based on the billing rate in effect for the performance period. This revenue recognition timing does not affect billings to customers, and differences between amounts billed and revenue recognized are recorded as contract assets or liabilities, as appropriate. • Aid in construction. Under Topic 605, aid in construction reimbursements were reflected as a reduction to property, plant and equipment upon receipt (and a reduction to capital expenditures). Under Topic 606, reimbursement of capital costs received from customers is reflected as a contract liability (deferred revenue) upon receipt. The contract liability is amortized to Service revenues – fee based over the expected period of customer benefit, which is generally the life of the related properties. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) • Percent-of-proceeds gathering / processing. Under Topic 605, WES recognized cost of product expense when the product was purchased from a producer to whom it provides services, and WES recognized revenue when the product was sold to Anadarko or a third party. Under Topic 606, in some instances, where all or a percentage of the proceeds from the sale must be returned to the producer, the net margin from the purchase and sale transactions is presented net within Service revenues – product based because WES is acting as the producer’s agent in the product sale. • Noncash consideration - keep-whole and percent-of-product agreements. Under Topic 605, WES recognized revenues only upon the sale of the related products. Under Topic 606, (i) Service revenues – product based is recognized for the products received as noncash consideration in exchange for the services provided, with the keep-whole noncash consideration value based on the net value of the NGLs over the replacement residue gas cost, and (ii) product sales revenue is recognized, along with cost of product expense related to the sale, when the product is sold to Anadarko or a third party. When the product is sold to Anadarko, Anadarko is acting as WES’s agent in the product sale and WES recognizes revenue, along with cost of product expense related to the sale, based on the Anadarko sales price to the third party, resulting in no impact to operating income. • Wellhead purchase / sale incorporated into gathering / processing. Under Topic 605, the natural gas purchase cost was recognized as cost of product expense and any specified gathering or processing fees charged to the producer were recognized as revenues. Under Topic 606, the fees charged to the producer under this contract type are recognized as adjustments to the amount recognized in cost of product expense instead of revenues when such fees relate to services performed after control of the product transfers to WES. The following tables summarize the impact of adopting Topic 606 on the impacted line items within the consolidated statements of operations and the consolidated balance sheet. The differences between revenue as reported following Topic 606 and revenue as it would have been reported under Topic 605 are due to the changes described above. Three Months Ended thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Revenues Service revenues – fee based $ 409,106 $ 396,161 $ 12,945 Service revenues – product based 22,735 — 22,735 Product sales 75,150 366,603 (291,453 ) Expenses Cost of product 105,966 353,641 (247,675 ) Operation and maintenance 111,359 111,327 32 Depreciation and amortization 82,553 81,824 729 Income tax (benefit) expense 1,517 1,580 (63 ) Net income (loss) attributable to noncontrolling interests 47,203 40,471 6,732 Net income (loss) attributable to Western Gas Equity Partners, LP 107,474 123,002 (15,528 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Nine Months Ended thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Revenues Service revenues – fee based $ 1,146,099 $ 1,096,708 $ 49,391 Service revenues – product based 67,433 — 67,433 Product sales 217,738 978,127 (760,389 ) Expenses Cost of product 303,518 940,936 (637,418 ) Operation and maintenance 300,266 300,098 168 Depreciation and amortization 238,187 236,102 2,085 Impairments 152,708 152,663 45 Income tax (benefit) expense 3,301 3,361 (60 ) Net income (loss) attributable to noncontrolling interests 63,669 89,339 (25,670 ) Net income (loss) attributable to Western Gas Equity Partners, LP 276,059 258,774 17,285 September 30, 2018 thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Assets Other current assets $ 26,119 $ 23,371 $ 2,748 Net property, plant and equipment 6,418,634 6,320,225 98,409 Other assets 14,057 13,894 163 Liabilities Accrued liabilities 114,504 106,810 7,694 Deferred income taxes 10,285 10,519 (234 ) Other liabilities 141,957 2,781 139,176 Equity and partners’ capital Total equity and partners’ capital 3,616,640 3,661,956 (45,316 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) New accounting standards issued but not yet adopted. ASU 2016-02, Leases (Topic 842) requires lessees to recognize a lease liability and a right-of-use (“ROU”) asset for all leases, including operating leases, with a term greater than 12 months on the balance sheet. This ASU modifies the definition of a lease and outlines the recognition, measurement, presentation, and disclosure of leasing arrangements by both lessees and lessors. WGP plans to make certain elections allowing WGP not to reassess contracts that commenced prior to adoption, to continue applying WES’s current accounting policy for existing or expired land easements and not to recognize ROU assets or lease liabilities for short-term leases. WGP continues to review contracts in WES’s portfolio of leased assets to assess the impact of adopting this ASU, which is expected to primarily impact other assets and other long-term liabilities. To facilitate compliance with this ASU, WES expects to implement new accounting software and complete the evaluation of its systems, processes and internal controls by the end of 2018. WGP will adopt this ASU on January 1, 2019, using a modified retrospective approach. As permitted by ASU 2018-11, Leases (Topic 842): Targeted Improvements , WGP does not expect to adjust comparative period financial statements. Revenue and cost of product. Upon adoption of the new revenue recognition standard on January 1, 2018 (discussed in Recently adopted accounting standards ), WGP changed its accounting policy for revenue recognition as described below. WES provides gathering, processing, treating, transportation and disposal services pursuant to a variety of contracts. Under these arrangements, WES receives fees and/or retains a percentage of products or a percentage of the proceeds from the sale of the customer’s products. These revenues are included in Service revenues and Product sales in the consolidated statements of operations. Payment is generally received from the customer in the month following the service or delivery of the product. Contracts with customers generally have initial terms ranging from 5 to 10 years. Service revenues – fee based is recognized for fee-based contracts in the month of service based on the volumes delivered by the customer. Producers’ wells or production facilities are connected to WES’s gathering systems for gathering, processing, treating, transportation and disposal of natural gas, NGLs, condensate, crude oil and produced water, as applicable. Revenues are valued based on the rate in effect for the month of service when the fee is either the same rate per unit over the contract term or when the fee escalates and the escalation factor approximates inflation. Deficiency fees charged to customers that do not meet their minimum delivery requirements are recognized as services are performed based on an estimate of the fees that will be billed upon completion of the performance period. Because of its significant upfront capital investment, WES may charge additional service fees to customers for only a portion of the contract term (i.e., for the first year of a contract or until reaching a volume threshold), and these fees are recognized as revenue over the expected period of customer benefit, which is generally the life of the related properties. WES also recognizes revenue and cost of product expense from marketing services performed on behalf of its customers by Anadarko. WES also receives Service revenues – fee based from contracts that have minimum volume commitment demand fees and fees that require periodic rate redeterminations based upon the related facility cost of service. These fees include fixed and variable consideration that are recognized on a consistent per-unit rate over the term of the contract. Annual adjustments are made to the cost of service rates charged to customers, and a cumulative catch-up revenue adjustment related to services already provided to the minimum volumes under the contract may be recorded in future periods, with revenues for the remaining term of the contract recognized on a consistent per-unit rate. Service revenues – product based includes service revenues from percent-of-proceeds gathering and processing contracts that are recognized net of the cost of product for purchases from WES’s customers since it is acting as the agent in the product sale. Keep-whole and percent-of-product agreements result in Service revenues – product based being recognized when the natural gas and/or NGLs are received from the customer as noncash consideration for the services provided. Noncash consideration for these services is valued at the time the services are provided. Revenue from product sales is also recognized, along with the cost of product expense related to the sale, when the product received as noncash consideration is sold to either Anadarko or a third party. When the product is sold to Anadarko, Anadarko is acting as WES’s agent in the product sale, with WES recognizing revenue and related cost of product expense associated with these marketing activities based on the Anadarko sales price to the third party. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) WES also purchases natural gas volumes from producers at the wellhead or from a production facility, typically at an index price, and charges the producer fees associated with the downstream gathering and processing services. When the fees relate to services performed after control of the product has transferred to WES, the fees are treated as a reduction of the purchase cost. Revenue from product sales is recognized, along with cost of product expense related to the sale, when the purchased product is sold to either Anadarko or a third party. WES receives aid in construction reimbursements for certain capital costs necessary to provide services to customers (i.e., connection costs, etc.) under certain service contracts. Aid in construction reimbursements are reflected as a contract liability upon receipt and amortized to Service revenues – fee based over the expected period of customer benefit, which is generally the life of the related properties.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	2. REVENUE FROM CONTRACTS WITH CUSTOMERS The following table summarizes revenue from contracts with customers: thousands Three Months Ended Nine Months Ended Revenue from customers Service revenues – fee based $ 409,106 $ 1,146,099 Service revenues – product based 22,735 67,433 Product sales 78,887 224,089 Total revenue from customers 510,728 1,437,621 Revenue from other than customers Net gains (losses) on commodity price swap agreements (3,737 ) (6,351 ) Other 771 1,213 Total revenues and other $ 507,762 $ 1,432,483 2. REVENUE FROM CONTRACTS WITH CUSTOMERS (CONTINUED) Contract balances. Receivables from customers, which are included in Accounts receivable, net on the consolidated balance sheets were $298.2 million and $244.4 million as of September 30, 2018 , and December 31, 2017 , respectively. Contract assets primarily relate to accrued deficiency fees WES expects to charge customers once the related performance periods are completed. The following table summarizes the current period activity related to contract assets from contracts with customers: thousands Balance at December 31, 2017 $ — Cumulative effect of adopting Topic 606 5,129 Amounts transferred to Accounts receivable, net from contract assets recognized in the adoption effect (1) (4,358 ) Additional estimated revenues recognized (2) 2,140 Balance at September 30, 2018 $ 2,911 Contract assets at September 30, 2018 Other current assets $ 2,748 Other assets 163 Total contract assets from contracts with customers $ 2,911 (1) Includes $(1.7) million for the three months ended September 30, 2018 . (2) Includes $(5.0) million for the three months ended September 30, 2018 . Contract liabilities primarily relate to (i) fees that are charged to customers for only a portion of the contract term and must be recognized as revenues over the expected period of customer benefit, (ii) fixed and variable fees under cost of service contracts that are received from customers for which revenue recognition is deferred and (iii) aid in construction payments received from customers that must be recognized over the expected period of customer benefit. The following table summarizes the current period activity related to contract liabilities from contracts with customers: thousands Balance at December 31, 2017 $ — Cumulative effect of adopting Topic 606 120,717 Cash received or receivable, excluding revenues recognized during the period (1) 37,340 Revenues recognized during the period that were included in the adoption effect (2) (10,850 ) Balance at September 30, 2018 $ 147,207 Contract liabilities at September 30, 2018 Accrued liabilities $ 8,031 Other liabilities 139,176 Total contract liabilities from contracts with customers $ 147,207 (1) Includes $(3.7) million for the three months ended September 30, 2018 . (2) Includes $(8.8) million for the three months ended September 30, 2018 , of which $(7.5) million was from a performance obligation satisfied in a previous period related to the arbitration against SWEPI LP (see Note 11 ). 2. REVENUE FROM CONTRACTS WITH CUSTOMERS (CONTINUED) Transaction price allocated to remaining performance obligations. Revenues expected to be recognized from certain performance obligations that are unsatisfied (or partially unsatisfied) as of September 30, 2018 , are reflected in the following table. WGP applies the optional exemptions in Topic 606 and does not disclose consideration for remaining performance obligations with an original expected duration of one year or less or for variable consideration related to unsatisfied (or partially unsatisfied) performance obligations. Therefore, the following table represents only a small portion of expected future revenues from existing contracts as most future revenues from customers are dependent on future variable customer volumes and in some cases variable commodity prices for those volumes. thousands Remainder of 2018 $ 124,395 2019 480,211 2020 545,223 2021 524,810 2022 528,900 Thereafter 2,191,811 Total $ 4,395,350

Acquisitions and Divestitures

Acquisitions and Divestitures	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Acquisitions and Divestitures	3. ACQUISITIONS AND DIVESTITURES Whitethorn LLC acquisition. In June 2018, WES acquired a 20% interest in Whitethorn LLC, which owns a crude oil and condensate pipeline that originates in Midland, Texas and terminates in Sealy, Texas (the “Midland-to-Sealy pipeline”) and related storage facilities (collectively referred to as “Whitethorn”). A third party operates Whitethorn and oversees the related commercial activities. In connection with its investment in Whitethorn, WES will share proportionally in the commercial activities. WES acquired its 20% interest via a $150.6 million net investment, which was funded with cash on hand and is accounted for under the equity method. See Note 8 . Cactus II acquisition. In June 2018, WES acquired a 15% interest in Cactus II, which will own a crude oil pipeline operated by a third party (the “Cactus II pipeline”) connecting West Texas to the Corpus Christi area. The Cactus II pipeline is under construction and expected to become operational in the fourth quarter of 2019. WES acquired its 15% interest from a third party via an initial net investment of $11.3 million , which represented its share of costs incurred up to the date of acquisition. The initial investment was funded with cash on hand and the interest in Cactus II is accounted for under the equity method. See Note 8 . Property exchange. On March 17, 2017, WES acquired an additional 50% interest in the Delaware Basin JV Gathering LLC (“DBJV”) system (the “Additional DBJV System Interest”) from a third party in exchange for (a) WES’s 33.75% non-operated interest in two natural gas gathering systems located in northern Pennsylvania (the “Non-Operated Marcellus Interest”), commonly referred to as the Liberty and Rome systems, and (b) $155.0 million of cash consideration (collectively, the “Property Exchange”). WES previously held a 50% interest in, and operated, the DBJV system. The Property Exchange was reflected as a nonmonetary transaction whereby the acquired Additional DBJV System Interest was recorded at the fair value of the divested Non-Operated Marcellus Interest plus the $155.0 million of cash consideration. The Property Exchange resulted in a net gain of $125.7 million recorded as Gain (loss) on divestiture and other, net in the consolidated statements of operations. Results of operations attributable to the Property Exchange were included in the consolidated statements of operations beginning on the acquisition date in the first quarter of 2017. DBJV acquisition - Deferred purchase price obligation - Anadarko. Prior to WES’s agreement with Anadarko to settle its deferred purchase price obligation early, the consideration that would have been paid by WES for the March 2015 acquisition of DBJV from Anadarko consisted of a cash payment to Anadarko due on March 31, 2020. In May 2017, WES reached an agreement with Anadarko to settle this obligation with a cash payment to Anadarko of $37.3 million , which was equal to the estimated net present value of the obligation at March 31, 2017. 3. ACQUISITIONS AND DIVESTITURES (CONTINUED) Helper and Clawson systems divestiture. During the second quarter of 2017, the Helper and Clawson systems, located in Utah, were sold to a third party, resulting in a net gain on sale of $16.3 million recorded as Gain (loss) on divestiture and other, net in the consolidated statements of operations.

Partnership Distributions

Partnership Distributions	9 Months Ended
	Sep. 30, 2018
Distributions Made to Members or Limited Partners [Abstract]
Partnership Distributions	4. PARTNERSHIP DISTRIBUTIONS WGP partnership distributions. WGP’s partnership agreement requires WGP to distribute all of its available cash (as defined in its partnership agreement) to WGP unitholders of record on the applicable record date within 55 days of the end of each quarter. The Board of Directors of WGP GP (the “Board of Directors”) declared the following cash distributions to WGP unitholders for the periods presented: thousands except per-unit amounts Quarters Ended Total Quarterly Distribution per Unit Total Quarterly Cash Distribution Date of Distribution 2017 March 31 $ 0.49125 $ 107,549 May 2017 June 30 0.52750 115,487 August 2017 September 30 0.53750 117,677 November 2017 December 31 0.54875 120,140 February 2018 2018 March 31 $ 0.56875 $ 124,518 May 2018 June 30 0.58250 127,531 August 2018 September 30 (1) 0.59500 130,268 November 2018 (1) The Board of Directors declared a cash distribution to WGP unitholders for the third quarter of 2018 of $0.59500 per unit, or $130.3 million in aggregate. The cash distribution is payable on November 21, 2018 , to WGP unitholders of record at the close of business on October 31, 2018 . WES partnership distributions. WES’s partnership agreement requires WES to distribute all of its available cash (as defined in WES’s partnership agreement) to WES unitholders of record on the applicable record date within 45 days of the end of each quarter. The Board of Directors of WES GP declared the following cash distributions to WES’s common and general partner unitholders for the periods presented: thousands except per-unit amounts Quarters Ended Total Quarterly Total Quarterly Date of 2017 March 31 $ 0.875 $ 188,753 May 2017 June 30 0.890 207,491 August 2017 September 30 0.905 212,038 November 2017 December 31 0.920 216,586 February 2018 2018 March 31 $ 0.935 $ 221,133 May 2018 June 30 0.950 225,691 August 2018 September 30 (1) 0.965 230,239 November 2018 (1) The Board of Directors of WES GP declared a cash distribution to WES unitholders for the third quarter of 2018 of $0.965 per unit, or $230.2 million in aggregate, including incentive distributions, but excluding distributions on WES Class C units (see WES Class C unit distributions below). The cash distribution is payable on November 13, 2018 , to WES unitholders of record at the close of business on October 31, 2018 . 4. PARTNERSHIP DISTRIBUTIONS (CONTINUED) WES’s available cash. The amount of available cash (as defined in WES’s partnership agreement) generally is all cash on hand at the end of the quarter, plus, at the discretion of WES GP, working capital borrowings made subsequent to the end of such quarter, less the amount of cash reserves established by WES GP to provide for the proper conduct of WES’s business, including reserves to fund future capital expenditures; to comply with applicable laws, debt instruments or other agreements; or to provide funds for distributions to WES unitholders and to WES GP for any one or more of the next four quarters. Working capital borrowings generally include borrowings made under a credit facility or similar financing arrangement. Working capital borrowings may only be those that, at the time of such borrowings, were intended to be repaid within 12 months. In all cases, working capital borrowings are used solely for working capital purposes or to fund distributions to partners. WES Class C unit distributions. WES’s Class C units receive quarterly distributions at a rate equivalent to WES’s common units. The distributions are paid in the form of additional Class C units (“PIK Class C units”) until the scheduled conversion date on March 1, 2020 (unless earlier converted), and the Class C units are disregarded with respect to WES’s distributions of WES’s available cash until they are converted into WES common units. The number of additional PIK Class C units to be issued in connection with a distribution payable on the Class C units is determined by dividing the corresponding distribution attributable to the Class C units by the volume-weighted-average price of WES’s common units for the ten days immediately preceding the payment date for the WES common unit distribution, less a 6% discount. WES records the PIK Class C unit distributions at fair value at the time of issuance. This Level 2 fair value measurement uses WES’s unit price as a significant input in the determination of the fair value. See Note 5 for further discussion of the WES Class C units. WES Series A Preferred unit distributions. As further described in Note 5 , WES issued Series A Preferred units representing limited partner interests in WES to private investors in 2016. The Series A Preferred unitholders received quarterly distributions in cash equal to $0.68 per Series A Preferred unit, subject to certain adjustments. On March 1, 2017, 50% of the outstanding WES Series A Preferred units converted into WES common units on a one -for-one basis, and on May 2, 2017, all remaining WES Series A Preferred units converted into WES common units on a one -for-one basis. Such converted WES common units were entitled to distributions made to WES common unitholders with respect to the quarter during which the applicable conversion occurred and did not include a prorated WES Series A Preferred unit distribution. For the quarter ended March 31, 2017, the WES Series A Preferred unitholders received an aggregate cash distribution of $7.5 million (paid in May 2017). WES’s general partner interest and incentive distribution rights. As of September 30, 2018 , WES GP was entitled to 1.5% of all quarterly distributions that WES makes prior to its liquidation and, as the holder of the incentive distribution rights (“IDRs”), was entitled to incentive distributions at the maximum distribution sharing percentage of 48.0% for all periods presented, after the minimum quarterly distribution and the target distribution levels had been achieved. The maximum distribution sharing percentage of 49.5% does not include any distributions that WES GP may receive on common units that it may acquire.

Equity and Partners' Capital

Equity and Partners' Capital	9 Months Ended
	Sep. 30, 2018
Partners' Capital Notes [Abstract]
Equity and Partners' Capital	5. EQUITY AND PARTNERS’ CAPITAL Holdings of WGP equity. WGP’s common units are listed on the New York Stock Exchange under the symbol “WGP.” As of September 30, 2018 , Anadarko held 170,380,161 WGP common units, representing a 77.8% limited partner interest in WGP, and, through its ownership of WGP GP, Anadarko indirectly held the entire non-economic general partner interest in WGP. The public held 48,557,636 WGP common units, representing a 22.2% limited partner interest in WGP. Tangible equity units. In June 2015, Anadarko completed the public issuance of 9,200,000 7.50% tangible equity units (“TEUs”), including 1,200,000 TEUs pursuant to the full exercise of the underwriters’ over-allotment option, at a price to the public of $50.00 per TEU. Each TEU that Anadarko issued consisted of (1) a prepaid equity purchase contract for WGP common units owned by Anadarko (which was subject to Anadarko’s right to elect to deliver shares of its common stock in lieu of such WGP common units) and (2) a senior amortizing note that was due June 7, 2018 . On June 7, 2018, the mandatory settlement date, Anadarko settled the 9,200,000 then outstanding TEUs by delivering to the holders 8,207,204 of its WGP common units in exchange for the prepaid equity purchase contracts. WGP did not receive any proceeds from, or incur any expense in, the public offering or settlement of the TEUs. Net income (loss) per common unit. For WGP, basic net income (loss) per common unit is calculated by dividing the limited partners’ interest in net income (loss) by the weighted-average number of common units outstanding during the period. Dilutive net income (loss) per common unit is calculated by dividing the limited partners’ interest in net income (loss) adjusted for distributions on the WES Series A Preferred units and a reallocation of the limited partners’ interest in net income (loss) assuming, prior to the actual conversion, conversion of the WES Series A Preferred units into WES common units, by the weighted-average number of WGP common units outstanding during the period. As of May 2, 2017, all WES Series A Preferred units were converted into WES common units on a one-for-one basis. The impact of the Series A Preferred units assuming, prior to the actual conversion, conversion to WES common units would be anti-dilutive for the nine months ended September 30, 2017 . Net income (loss) per common unit is calculated assuming that cash distributions are equal to the net income attributable to WGP. Net income (loss) attributable to the WES assets (as defined in Note 1 ) acquired from Anadarko for periods prior to WES’s acquisition of the WES assets is not allocated to the limited partners when calculating net income (loss) per common unit. Net income equal to the amount of available cash (as defined by WGP’s partnership agreement) is allocated to WGP common unitholders consistent with actual cash distributions. Holdings of WES equity. As of September 30, 2018 , WGP held 50,132,046 WES common units, representing a 29.6% limited partner interest in WES, and, through its ownership of WES GP, WGP indirectly held 2,583,068 general partner units, representing a 1.5% general partner interest in WES, and 100% of WES’s IDRs. As of September 30, 2018 , (i) other subsidiaries of Anadarko collectively held 2,011,380 WES common units and 14,045,429 Class C units, representing an aggregate 9.5% limited partner interest in WES and (ii) the public held 100,465,859 WES common units, representing a 59.4% limited partner interest in WES, which are all reflected as noncontrolling interests within the consolidated financial statements of WGP (see Note 1 ). WES equity offerings. In July 2017, WES filed a registration statement with the SEC for the issuance of up to an aggregate of $500.0 million of WES common units pursuant to a new continuous offering program that has not yet been initiated. WES Class C units. In November 2014, WES issued 10,913,853 Class C units to APC Midstream Holdings, LLC (“AMH”), pursuant to a Unit Purchase Agreement with Anadarko and AMH. The Class C units were issued to partially fund WES’s acquisition of DBM. When issued, the WES Class C units were scheduled to convert into WES common units on a one -for-one basis on December 31, 2017. In February 2017, Anadarko elected to extend the conversion date of the WES Class C units to March 1, 2020. WES can elect to convert the Class C units earlier or Anadarko can extend the conversion date again. 5. EQUITY AND PARTNERS’ CAPITAL (CONTINUED) WES Series A Preferred units. In 2016, WES issued 21,922,831 Series A Preferred units to private investors. Pursuant to an agreement between WES and the holders of the WES Series A Preferred units, 50% of the WES Series A Preferred units converted into WES common units on a one -for-one basis on March 1, 2017, and all remaining Series A Preferred units converted into WES common units on a one -for-one basis on May 2, 2017. WES interests . The following table summarizes WES’s units issued during the nine months ended September 30, 2018 : WES Common Units WES Class C Units WES General Partner Units Total Balance at December 31, 2017 152,602,105 13,243,883 2,583,068 168,429,056 PIK Class C units — 801,546 — 801,546 Long-Term Incentive Plan award vestings 7,180 — — 7,180 Balance at September 30, 2018 152,609,285 14,045,429 2,583,068 169,237,782

Transactions with Affiliates

Transactions with Affiliates	9 Months Ended
	Sep. 30, 2018
Related Party Fees and Other Arrangements, Limited Liability Company (LLC) or Limited Partnership (LP) [Abstract]
Transactions with Affiliates	6. TRANSACTIONS WITH AFFILIATES Affiliate transactions. Revenues from affiliates include amounts earned by WES from services provided to Anadarko as well as from the sale of natural gas, condensate and NGLs to Anadarko. Anadarko sells such natural gas, condensate and NGLs as an agent on behalf of either WES or WES’s customers. When such sales are on WES’s customers’ behalf, WES recognizes associated service revenues and cost of product expense. When such sales are on WES’s behalf, WES recognizes product sales revenues based on the Anadarko sales price to the third party and cost of product expense associated with these sales activities. In addition, WES purchases natural gas, condensate and NGLs from an affiliate of Anadarko pursuant to gas purchase agreements. Operation and maintenance expense includes amounts accrued for or paid to affiliates for the operation of WES assets, whether in providing services to affiliates or to third parties, including field labor, measurement and analysis, and other disbursements. A portion of general and administrative expenses is paid by Anadarko, which results in affiliate transactions pursuant to the reimbursement provisions of the omnibus agreements of WES and WGP. Affiliate expenses do not bear a direct relationship to affiliate revenues, and third-party expenses do not bear a direct relationship to third-party revenues. Cash management. Anadarko operates a cash management system whereby excess cash from most of its subsidiaries’ separate bank accounts is generally swept to centralized accounts. Prior to the acquisition of WES assets, third-party sales and purchases related to such assets were received or paid in cash by Anadarko within its centralized cash management system. The outstanding affiliate balances were entirely settled through an adjustment to net investment by Anadarko in connection with the acquisition of WES assets. Subsequent to the acquisition of WES assets from Anadarko, transactions related to such assets are cash-settled directly with third parties and with Anadarko affiliates. Chipeta cash settles its transactions directly with third parties and Anadarko, as well as with the other subsidiaries of WES. Note receivable - Anadarko. Concurrently with the closing of WES’s May 2008 initial public offering, WES loaned $260.0 million to Anadarko in exchange for a 30-year note bearing interest at a fixed annual rate of 6.50% , payable quarterly. The fair value of the note receivable from Anadarko was $300.9 million and $325.2 million at September 30, 2018 , and December 31, 2017 , respectively. The fair value of the note reflects consideration of credit risk and any premium or discount for the differential between the stated interest rate and quarter-end market interest rate, based on quoted market prices of similar debt instruments. Accordingly, the fair value of the note receivable from Anadarko is measured using Level 2 inputs. 6. TRANSACTIONS WITH AFFILIATES (CONTINUED) Commodity price swap agreements. WES has commodity price swap agreements with Anadarko to mitigate exposure to a majority of the commodity price risk inherent in its percent-of-proceeds, percent-of-product and keep-whole contracts. Notional volumes for each of the commodity price swap agreements are not specifically defined. Instead, the commodity price swap agreements apply to the actual volume of natural gas, condensate and NGLs purchased and sold. The commodity price swap agreements do not satisfy the definition of a derivative financial instrument and, therefore, are not required to be measured at fair value. WES’s net gains (losses) on commodity price swap agreements were $(3.7) million and $(6.4) million for the three and nine months ended September 30, 2018 , respectively, and $(1.0) million and $(0.6) million for the three and nine months ended September 30, 2017 , respectively, and are reported in the consolidated statements of operations as affiliate Product sales in 2018 and as affiliate Product sales and Cost of product expense in 2017 (see Note 1 ). Revenues or costs attributable to volumes sold and purchased during 2017 and 2018 for the DJ Basin complex and MGR assets are recognized in the consolidated statements of operations at the applicable market price in the tables below. WES also records a capital contribution from Anadarko in its consolidated statement of equity and partners’ capital for an amount equal to (i) the amount by which the swap price for product sales exceeds the applicable market price in the tables below, minus (ii) the amount by which the swap price for product purchases exceeds the market price in the tables below. For the nine months ended September 30, 2018 , the capital contribution from Anadarko was $40.7 million . The tables below summarize the swap prices compared to the forward market prices: DJ Basin Complex per barrel except natural gas 2017 - 2018 Swap Prices 2017 Market Prices (1) 2018 Market Prices (1) Ethane $ 18.41 $ 5.09 $ 5.41 Propane 47.08 18.85 28.72 Isobutane 62.09 26.83 32.92 Normal butane 54.62 26.20 32.71 Natural gasoline 72.88 41.84 48.04 Condensate 76.47 45.40 49.36 Natural gas (per MMBtu) 5.96 3.05 2.21 MGR Assets per barrel except natural gas 2017 - 2018 Swap Prices 2017 Market Prices (1) 2018 Market Prices (1) Ethane $ 23.11 $ 4.08 $ 2.52 Propane 52.90 19.24 25.83 Isobutane 73.89 25.79 30.03 Normal butane 64.93 25.16 29.82 Natural gasoline 81.68 45.01 47.25 Condensate 81.68 53.55 56.76 Natural gas (per MMBtu) 4.87 3.05 2.21 (1) Represents the New York Mercantile Exchange forward strip price as of December 1, 2016, and December 20, 2017 , for the 2017 Market Prices and 2018 Market Prices, respectively, adjusted for product specification, location, basis and, in the case of NGLs, transportation and fractionation costs. 6. TRANSACTIONS WITH AFFILIATES (CONTINUED) Gathering and processing agreements. WES has significant gathering and processing arrangements with affiliates of Anadarko on a majority of its systems. WES’s natural gas gathering, treating and transportation throughput (excluding equity investment throughput) attributable to production owned or controlled by Anadarko was 41% and 37% for the three and nine months ended September 30, 2018 , respectively, and 33% and 34% for the three and nine months ended September 30, 2017 , respectively. WES’s natural gas processing throughput (excluding equity investment throughput) attributable to production owned or controlled by Anadarko was 35% for both the three and nine months ended September 30, 2018 , and 39% and 42% for the three and nine months ended September 30, 2017 , respectively. WES’s crude oil, NGL and produced water gathering, treating, transportation and disposal throughput (excluding equity investment throughput) attributable to production owned or controlled by Anadarko was 77% and 71% for the three and nine months ended September 30, 2018 , respectively, and 54% and 50% for the three and nine months ended September 30, 2017 , respectively. Commodity purchase and sale agreements. WES sells a significant amount of its natural gas, condensate and NGLs to Anadarko Energy Services Company (“AESC”), Anadarko’s marketing affiliate that acts as an agent in the sale to a third party. In addition, WES purchases natural gas, condensate and NGLs from AESC pursuant to purchase agreements. WES’s purchase and sale agreements with AESC are generally one-year contracts, subject to annual renewal. WGP LTIP. WGP GP awards phantom units under the Western Gas Equity Partners, LP 2012 Long-Term Incentive Plan (the “WGP LTIP”) to its independent directors and executive officers. The phantom units awarded to the independent directors vest one year from the grant date, while awards granted to executive officers are subject to graded vesting over a three -year service period. Compensation expense under the WGP LTIP is recognized over the vesting period and was $62,000 and $0.2 million for the three and nine months ended September 30, 2018 , respectively, and $63,000 and $0.2 million for the three and nine months ended September 30, 2017 , respectively. Anadarko Incentive Plan. General and administrative expenses included $1.4 million and $5.2 million for the three and nine months ended September 30, 2018 , respectively, and $1.2 million and $3.2 million for the three and nine months ended September 30, 2017 , respectively, of equity-based compensation expense, allocated to WES by Anadarko, for awards granted to the executive officers of WES GP and other employees under the Anadarko Petroleum Corporation 2012 Omnibus Incentive Compensation Plan (“Anadarko Incentive Plan”). Of this amount, $4.3 million is reflected as contributions to partners’ capital in the consolidated statement of equity and partners’ capital for the nine months ended September 30, 2018 . WES LTIP. WES GP awards phantom units under the Western Gas Partners, LP 2017 Long-Term Incentive Plan, effective October 17, 2017. Awards granted prior to October 17, 2017, were awarded under the Western Gas Partners, LP 2008 Long-Term Incentive Plan. These awards are primarily granted to its independent directors, but also from time to time to its executive officers and Anadarko employees performing services for WES. The phantom units awarded to the independent directors vest one year from the grant date, while all other awards are subject to graded vesting over a three -year service period. Compensation expense is recognized over the vesting period and was $0.1 million for each of the three months ended September 30, 2018 and 2017, and $0.3 million for each of the nine months ended September 30, 2018 and 2017. Purchases. The following table summarizes WES’s purchases from Anadarko of pipe and equipment: Nine Months Ended September 30, thousands 2018 2017 Cash consideration $ 254 $ 3,910 Net carrying value (254 ) (5,283 ) Partners’ capital adjustment $ — $ (1,373 ) 6. TRANSACTIONS WITH AFFILIATES (CONTINUED) Contributions in aid of construction costs from affiliates. On certain of WES’s capital projects, Anadarko is obligated to reimburse WES for all or a portion of project capital expenditures. The majority of such arrangements are associated with projects related to pipeline construction activities and production well tie-ins. For periods prior to January 1, 2018, the cash receipts resulting from such reimbursements were presented as “Contributions in aid of construction costs from affiliates” within the investing section of the consolidated statements of cash flows. As discussed in Recently adopted accounting standards in Note 1 , upon adoption of Topic 606, affiliate reimbursements of capital costs are reflected as contract liabilities upon receipt, amortized to Service revenues – fee based over the expected period of customer benefit, and presented within the operating section of the consolidated statements of cash flows. Summary of affiliate transactions. The following table summarizes material affiliate transactions: Three Months Ended Nine Months Ended thousands 2018 2017 2018 2017 Revenues and other (1) $ 274,514 $ 351,127 $ 766,179 $ 982,595 Equity income, net – affiliates (1) 43,110 21,519 102,752 62,708 Cost of product (1) 46,971 22,902 131,428 60,497 Operation and maintenance (2) 25,145 18,110 68,830 53,661 General and administrative (3) 11,780 10,414 35,000 29,637 Operating expenses 83,896 51,426 235,258 143,795 Interest income (4) 4,225 4,225 12,675 12,675 Interest expense (5) — — — 71 Settlement of the Deferred purchase price obligation – Anadarko (6) — — — (37,346 ) Distributions to WGP unitholders (7) 99,247 94,205 298,818 264,533 Distributions to WES unitholders (8) 1,911 1,790 5,642 5,280 Above-market component of swap agreements with Anadarko 12,601 18,049 40,722 46,719 (1) Represents amounts earned or incurred on and subsequent to the date of the 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. (2) 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. (3) Represents general and administrative expense incurred on and subsequent to the date of the 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 Anadarko Incentive Plan within this Note 6 ) and amounts charged by Anadarko under the WGP and WES omnibus agreements. (4) Represents interest income recognized on the note receivable from Anadarko. (5) Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10 ) . (6) Represents the cash payment to Anadarko for the settlement of the Deferred purchase price obligation - Anadarko (see Note 3 ). (7) Represents distributions paid under WGP’s partnership agreement (see Note 4 and Note 5 ). (8) Represents distributions paid to other subsidiaries of Anadarko under WES’s partnership agreement (see Note 4 and Note 5 ). Concentration of credit risk. Anadarko was the only customer from whom revenues exceeded 10% of consolidated revenues for all periods presented in the consolidated statements of operations.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	7. PROPERTY, PLANT AND EQUIPMENT A summary of the historical cost of property, plant and equipment is as follows: thousands Estimated Useful Life September 30, December 31, Land n/a $ 4,653 $ 4,450 Gathering systems and processing complexes 3 to 47 years 7,883,265 7,113,114 Pipelines and equipment 15 to 45 years 137,769 137,644 Assets under construction n/a 856,092 579,501 Other 3 to 40 years 30,976 29,826 Total property, plant and equipment 8,912,755 7,864,535 Less accumulated depreciation 2,494,121 2,133,644 Net property, plant and equipment $ 6,418,634 $ 5,730,891 The cost of property classified as “Assets under construction” is excluded from capitalized costs being depreciated. These amounts represent property that is not yet suitable to be placed into productive service as of the respective balance sheet date. Impairments. During the nine months ended September 30, 2018 , WES recognized impairments of $152.7 million , including impairments of $125.9 million at the Third Creek gathering system and $8.1 million at the Kitty Draw gathering system. These assets were impaired to their estimated salvage values of $1.8 million and zero , respectively, using the market approach and Level 3 fair value inputs, due to the shutdown of the systems. See Note 1 for further information. The remaining $18.7 million of impairments was primarily related to (i) a $10.9 million impairment at the GNB NGL pipeline, which was impaired to its estimated fair value of $10.0 million using the income approach and Level 3 fair value inputs, and (ii) a $5.6 million impairment related to an idle facility at the Chipeta complex, which was impaired to its estimated salvage value of $1.5 million using the market approach and Level 3 fair value inputs. During the year ended December 31, 2017, WES recognized impairments of $178.4 million , including an impairment of $158.8 million at the Granger complex, which was impaired to its estimated fair value of $48.5 million using the income approach and Level 3 fair value inputs, due to a reduced throughput fee as a result of a producer’s bankruptcy. The remaining $19.6 million of impairments was primarily related to (i) an $8.2 million impairment due to the cancellation of a plant project at the Hilight system, (ii) a $3.7 million impairment at the Granger straddle plant, which was impaired to its estimated salvage value of $0.6 million using the income approach and Level 3 fair value inputs, (iii) a $3.1 million impairment of the Fort Union equity investment, (iv) a $2.0 million impairment of an idle facility in northeast Wyoming, which was impaired to its estimated salvage value of $0.4 million using the market approach and Level 3 fair value inputs, and (v) the cancellation of a pipeline project in West Texas.

Equity Investments

Equity Investments	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	8. EQUITY INVESTMENTS The following table presents the activity in WES’s equity investments for the nine months ended September 30, 2018 : thousands Fort White Rendezvous Mont TEFR Interests Whitethorn Cactus II Total Balance at December 31, 2017 $ 7,030 $ 44,945 $ 42,528 $ 110,299 $ 361,409 $ — $ — $ 566,211 Acquisitions — — — — — 150,563 11,295 161,858 Investment earnings (loss), net of amortization (892 ) 8,547 635 22,916 47,736 23,810 — 102,752 Contributions — 1,278 — — 24,680 7,069 34,436 67,463 Capitalized interest — — — — — — 516 516 Distributions (194 ) (8,111 ) (2,091 ) (22,945 ) (43,989 ) (16,497 ) — (93,827 ) Distributions in excess of cumulative earnings (1) (2,889 ) (3,109 ) (2,015 ) (3,305 ) (6,779 ) — — (18,097 ) Balance at September 30, 2018 $ 3,055 $ 43,550 $ 39,057 $ 106,965 $ 383,057 $ 164,945 $ 46,247 $ 786,876 (1) Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, are calculated on an individual investment basis.

Components of Working Capital

Components of Working Capital	9 Months Ended
	Sep. 30, 2018
Components Of Working Capital [Abstract]
Components of Working Capital	9. COMPONENTS OF WORKING CAPITAL A summary of accounts receivable, net is as follows: thousands September 30, 2018 December 31, 2017 Trade receivables, net $ 224,719 $ 160,194 Other receivables, net 168 45 Total accounts receivable, net $ 224,887 $ 160,239 A summary of other current assets is as follows: thousands September 30, 2018 December 31, 2017 Natural gas liquids inventory $ 11,212 $ 10,788 Imbalance receivables 3,829 1,640 Prepaid insurance 3,203 2,955 Contract assets 2,748 — Other 5,127 — Total other current assets $ 26,119 $ 15,383 9. COMPONENTS OF WORKING CAPITAL (CONTINUED) A summary of accrued liabilities is as follows: thousands September 30, 2018 December 31, 2017 Accrued interest expense $ 54,556 $ 40,646 Short-term asset retirement obligations (1) 42,872 2,304 Short-term remediation and reclamation obligations 833 833 Income taxes payable 247 2,495 Contract liabilities 8,031 — Other 7,965 1,714 Total accrued liabilities $ 114,504 $ 47,992 (1) As of September 30, 2018 , includes $40.2 million of short-term liabilities incurred during the second quarter of 2018 related to the shutdowns at the Third Creek and Kitty Draw gathering systems. See Note 1 for further information.

Debt and Interest Expense

Debt and Interest Expense	9 Months Ended
	Sep. 30, 2018
Debt Instruments [Abstract]
Debt and Interest Expense	10. DEBT AND INTEREST EXPENSE The following table presents WES and WGP’s outstanding debt: September 30, 2018 December 31, 2017 thousands Principal Carrying Value Fair Value (1) Principal Carrying Value Fair Value (1) Short-term debt WGP RCF $ 28,000 $ 28,000 $ 28,000 $ — $ — $ — WGP long-term debt WGP RCF $ — $ — $ — $ 28,000 $ 28,000 $ 28,000 WES long-term debt 2.600% Senior Notes due 2018 — — — 350,000 349,684 350,631 5.375% Senior Notes due 2021 500,000 496,669 517,160 500,000 495,815 530,647 4.000% Senior Notes due 2022 670,000 669,020 668,198 670,000 668,849 684,043 3.950% Senior Notes due 2025 500,000 492,596 478,470 500,000 491,885 500,885 4.650% Senior Notes due 2026 500,000 495,592 492,502 500,000 495,245 520,144 4.500% Senior Notes due 2028 400,000 394,514 384,964 — — — 4.750% Senior Notes due 2028 400,000 395,806 391,532 — — — 5.450% Senior Notes due 2044 600,000 593,319 565,485 600,000 593,234 637,827 5.300% Senior Notes due 2048 700,000 686,601 645,643 — — — 5.500% Senior Notes due 2048 350,000 342,347 331,981 — — — WES RCF — — — 370,000 370,000 370,000 Total long-term debt $ 4,620,000 $ 4,566,464 $ 4,475,935 $ 3,518,000 $ 3,492,712 $ 3,622,177 (1) Fair value is measured using the market approach and Level 2 inputs. 10. DEBT AND INTEREST EXPENSE (CONTINUED) Debt activity. The following table presents WES and WGP’s debt activity for the nine months ended September 30, 2018 : thousands Carrying Value Balance at December 31, 2017 $ 3,492,712 WES RCF borrowings 320,000 Issuance of 4.500% Senior Notes due 2028 400,000 Issuance of 5.300% Senior Notes due 2048 700,000 Issuance of 4.750% Senior Notes due 2028 400,000 Issuance of 5.500% Senior Notes due 2048 350,000 Repayment of 2.600% Senior Notes due 2018 (350,000 ) Repayments of WES RCF borrowings (690,000 ) Other (28,248 ) Balance at September 30, 2018 $ 4,594,464 WGP RCF. In February 2018, WGP voluntarily reduced the aggregate commitments of the lenders under the WGP RCF, which matures in March 2019, to $35.0 million . As of September 30, 2018 , the outstanding borrowings under the WGP RCF were classified as short-term debt on the consolidated balance sheet. As of September 30, 2018 , WGP had $28.0 million of outstanding borrowings and $7.0 million available for borrowing under the WGP RCF. As of September 30, 2018 and 2017 , the interest rate on the outstanding WGP RCF borrowings was 4.25% and 3.24% , respectively. The commitment fee rate was 0.30% at September 30, 2018 and 2017 . At September 30, 2018 , WGP was in compliance with all covenants under the WGP RCF. WES Senior Notes. In August 2018, the 4.750% Senior Notes due 2028 and 5.500% Senior Notes due 2048 were offered to the public at prices of 99.818% and 98.912% , respectively, of the face amount. Including the effects of the issuance and underwriting discounts, the effective interest rates of the senior notes are 4.885% and 5.652% , respectively. Interest is paid on each such series semi-annually on February 15 and August 15 of each year, beginning February 15, 2019. The net proceeds were used to repay the maturing 2.600% Senior Notes due August 2018, repay amounts outstanding under the WES RCF and for WES’s general partnership purposes, including to fund capital expenditures. In March 2018, the 4.500% Senior Notes due 2028 and 5.300% Senior Notes due 2048 were offered to the public at prices of 99.435% and 99.169% , respectively, of the face amount. Including the effects of the issuance and underwriting discounts, the effective interest rates of the senior notes are 4.682% and 5.431% , respectively. Interest is paid on each such series semi-annually on March 1 and September 1 of each year, beginning September 1, 2018. The net proceeds were used to repay amounts outstanding under the WES RCF and for WES’s general partnership purposes, including to fund capital expenditures. At September 30, 2018 , WES was in compliance with all covenants under the indentures governing its outstanding notes. WES RCF. In February 2018, WES entered into the five-year $1.5 billion WES RCF by amending and restating the $1.2 billion credit facility that was originally entered into in February 2014. The WES RCF is expandable to a maximum of $2.0 billion , matures in February 2023, with options to extend maturity by up to two additional one year increments, and bears interest at the London Interbank Offered Rate (“LIBOR”), plus applicable margins ranging from 1.00% to 1.50% , or an alternate base rate equal to the greatest of (a) the Prime Rate, (b) the Federal Funds Effective Rate plus 0.50% , or (c) LIBOR plus 1.00% , in each case plus applicable margins currently ranging from zero to 0.50% , based upon WES’s senior unsecured debt rating. WES is required to pay a quarterly facility fee ranging from 0.125% to 0.250% of the commitment amount (whether used or unused), also based upon its senior unsecured debt rating. As of September 30, 2018 , WES had no outstanding borrowings and $4.6 million in outstanding letters of credit, resulting in $1,495.4 million available borrowing capacity under the WES RCF. As of September 30, 2018 and 2017 , the interest rate on any outstanding WES RCF borrowings was 3.56% and 2.54% , respectively. The facility fee rate was 0.20% at September 30, 2018 and 2017 . At September 30, 2018 , WES was in compliance with all covenants under the WES RCF. 10. DEBT AND INTEREST EXPENSE (CONTINUED) Interest expense. The following table summarizes the amounts included in interest expense: Three Months Ended Nine Months Ended thousands 2018 2017 2018 2017 Third parties Long-term and short-term debt $ (53,229 ) $ (36,223 ) $ (143,436 ) $ (106,412 ) Amortization of debt issuance costs and commitment fees (2,054 ) (2,009 ) (6,955 ) (5,955 ) Capitalized interest 6,967 2,115 17,032 3,991 Total interest expense – third parties (48,316 ) (36,117 ) (133,359 ) (108,376 ) Affiliates Deferred purchase price obligation – Anadarko (1) — — — (71 ) Total interest expense – affiliates — — — (71 ) Interest expense $ (48,316 ) $ (36,117 ) $ (133,359 ) $ (108,447 ) (1) See Note 3 for a discussion of the Deferred purchase price obligation - Anadarko.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. COMMITMENTS AND CONTINGENCIES Litigation and legal proceedings. In February 2017, DBJV, at the time a 50 / 50 joint venture between a third party and WES, initiated an arbitration against SWEPI LP (“SWEPI”) for breach of a 2007 gas gathering agreement between it and DBJV (the “GGA”). Specifically, DBJV sought to collect certain gathering fees under the GGA for the period January 1, 2016 to July 1, 2017. SWEPI disputed DBJV’s calculation of the cost of service based rate and filed a counterclaim alleging overpayment of fees under the GGA for the years 2013 through 2015. As part of the adoption of Topic 606 (see Note 1 ), during the first quarter of 2018, WES recorded a $7.5 million contract liability and reduced total equity and partners’ capital related to the counterclaim for the years 2013 through 2015 under the GGA revenue contract. The arbitration hearing concluded on June 27, 2018. On September 14, 2018, the panel issued a binding non-appealable decision awarding no damages to either DBJV or SWEPI. As such, during the third quarter of 2018, the previously recorded contract liability was reversed, resulting in a $7.5 million increase to Service revenues - fee based in the consolidated statements of operations. In addition, from time to time, WGP, through its partnership interests in WES, is involved in legal, tax, regulatory and other proceedings in various forums regarding performance, contracts and other matters that arise in the ordinary course of business. Management is not aware of any such proceeding for which the final disposition could have a material adverse effect on WGP’s financial condition, results of operations or cash flows. Other commitments. WES has short-term payment obligations, or commitments, related to its capital spending programs, as well as those of its unconsolidated affiliates, the majority of which is expected to be paid in the next twelve months. These commitments relate primarily to construction and expansion projects at the DBJV system and the DJ Basin and DBM complexes. Lease commitments. Anadarko, on WES’s behalf, has entered into lease arrangements for corporate offices, shared field offices and equipment supporting WES’s operations, for which Anadarko charges WES lease expense. The leases for the corporate off ices and shared field offices extend throu gh 2028 and 2033, res pectively . Lease expense charged to WES associated with these lease arrangements was $14.6 million and $40.5 million for the three and nine months ended September 30, 2018 , respectively, and $12.0 million and $32.7 million for the three and nine months ended September 30, 2017 , respectively.

Description of Business and B_2

Description of Business and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Consolidation policy	Basis of presentation. The following table outlines WES’s ownership interests and the accounting method of consolidation used in WES’s consolidated financial statements for entities not wholly owned: Percentage Interest Equity investments (1) Fort Union 14.81 % White Cliffs 10 % Rendezvous 22 % Mont Belvieu JV 25 % TEP 20 % TEG 20 % FRP 33.33 % Whitethorn 20 % Cactus II 15 % Proportionate consolidation (2) Marcellus Interest systems 33.75 % Newcastle system 50 % Springfield system 50.1 % Full consolidation Chipeta (3) 75 % (1) Investments in non-controlled entities over which WES exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to WES’s share of average throughput for these investments. (2) WGP proportionately consolidates WES’s associated share of the assets, liabilities, revenues and expenses attributable to these assets. (3) The 25% interest in Chipeta Processing LLC (“Chipeta”) held by a third-party member is reflected within noncontrolling interests in the consolidated financial statements, in addition to the noncontrolling interests noted below. The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). The consolidated financial statements include the accounts of WGP and entities in which it holds a controlling financial interest, including WES and WES GP. All significant intercompany transactions have been eliminated. Certain information and note disclosures commonly included in annual financial statements have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, the accompanying consolidated financial statements and notes should be read in conjunction with WGP’s 2017 Form 10-K, as filed with the SEC on February 16, 2018 . Management believes that the disclosures made are adequate to make the information not misleading. The consolidated financial results of WES are included in WGP’s consolidated financial statements due to WGP’s 100% ownership interest in WES GP and WES GP’s control of WES. Throughout these notes to consolidated financial statements, and to the extent material, any differences between the consolidated financial results of WGP and WES are discussed separately. WGP has no independent operations or material assets other than its partnership interests in WES. WGP’s consolidated financial statements differ from those of WES primarily as a result of (i) the presentation of noncontrolling interest ownership (attributable to the limited partner interests in WES held by the public, other subsidiaries of Anadarko and private investors, see Note 5 ), (ii) the elimination of WES GP’s investment in WES with WES GP’s underlying capital account, (iii) the general and administrative expenses incurred by WGP, which are separate from, and in addition to, those incurred by WES, (iv) the inclusion of the impact of WGP equity balances and WGP distributions, and (v) WGP’s senior secured revolving credit facility (“WGP RCF”). See Note 10 . Noncontrolling interests. WGP’s noncontrolling interests in the consolidated financial statements consist of the following for all periods presented: (i) the 25% interest in Chipeta held by a third-party member, (ii) the publicly held limited partner interests in WES, (iii) the 2,011,380 WES common units issued by WES to other subsidiaries of Anadarko as part of the consideration paid for the acquisitions of the Non-Operated Marcellus Interest, the TEFR Interests and Springfield Pipeline LLC (“Springfield”), and (iv) the WES Class C units issued by WES to a subsidiary of Anadarko as part of the funding for the acquisition of Delaware Basin Midstream, LLC (“DBM”). The WES Series A Preferred units issued to private investors as part of the funding of the Springfield acquisition were also noncontrolling interests in the consolidated financial statements until converted into WES common units in 2017. See Note 3 and Note 5 . When WES issues equity, the carrying amount of the noncontrolling interest reported by WGP is adjusted to reflect the noncontrolling ownership interest in WES. The resulting impact of such noncontrolling interest adjustment on WGP’s interest in WES is reflected as an adjustment to WGP’s partners’ capital.
Variable interest entity policy	Variable interest entity. WES is a variable interest entity (“VIE”) because the partners in WES with equity at risk lack the power, through voting or similar rights, to direct the activities that most significantly impact WES’s economic performance. A reporting entity that concludes it has a variable interest in a VIE must evaluate whether it has a controlling financial interest in the VIE, such that it is the VIE’s primary beneficiary and should consolidate. WGP is the primary beneficiary of WES and therefore should consolidate because (i) WGP has the power to direct the activities of WES that most significantly affect its economic performance and (ii) WGP has the right to receive benefits or the obligation to absorb losses that could be potentially significant to WES. As noted above, WGP has no independent operations or material assets other than its partnership interests in WES. The assets of WES cannot be used by WGP for general partnership purposes. WES’s long-term debt is recourse to WES GP, which is wholly owned by WGP. In turn, WES GP is indemnified by wholly owned subsidiaries of Anadarko for any claims made against WES GP under the indentures governing WES’s outstanding notes or borrowings under WES’s senior unsecured revolving credit facility (“WES RCF”). WES’s sources of liquidity include cash and cash equivalents, cash flows generated from operations, interest income on its $260.0 million note receivable from Anadarko, available borrowing capacity under the WES RCF, and issuances of additional equity or debt securities.
Business combinations policy	Presentation of WES assets. The term “WES assets” includes both the assets indirectly owned and the interests accounted for under the equity method by WGP through its partnership interests in WES as of September 30, 2018 (see Note 8 ). Because WGP owns the entire interest in and controls WES GP, and WGP GP is controlled by Anadarko, each of WES’s acquisitions of WES assets from Anadarko has been considered a transfer of net assets between entities under common control. As such, WES assets acquired from Anadarko were initially recorded at Anadarko’s historic carrying value, which did not correlate to the total acquisition price paid by WES. Further, after an acquisition of WES assets from Anadarko, WES and WGP (by virtue of its consolidation of WES) may be required to recast their financial statements to include the activities of such WES assets from the date of common control. For those periods requiring recast, the consolidated financial statements for periods prior to the acquisition of WES assets from Anadarko are prepared from Anadarko’s historical cost-basis accounts and may not necessarily be indicative of the actual results of operations that would have occurred if WES had owned the WES assets during the periods reported. Net income (loss) attributable to the WES assets acquired from Anadarko for periods prior to WES’s acquisition of the WES assets is not allocated to the limited partners.
Use of estimates policy	Use of estimates. In preparing financial statements in accordance with GAAP, management makes informed judgments and estimates that affect the reported amounts of assets, liabilities, revenues and expenses. Management evaluates its estimates and related assumptions regularly, using historical experience and other methods considered reasonable. Changes in facts and circumstances or additional information may result in revised estimates and actual results may differ from these estimates. Effects on the business, financial condition and results of operations resulting from revisions to estimates are recognized when the facts that give rise to the revisions become known. The information included herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the consolidated financial statements, and certain prior-period amounts have been reclassified to conform to the current-year presentation.
New accounting standards policy	Recently adopted accounting standards. Accounting Standards Update (“ASU”) 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash requires an entity to explain the changes in the total of cash, cash equivalents, restricted cash, and restricted cash equivalents on the statement of cash flows and to provide a reconciliation of the totals in that statement to the related captions in the balance sheet when the cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet. WGP adopted this ASU using a retrospective approach on January 1, 2018, and the adoption did not impact the consolidated financial statements. Revenue from contracts with customers (Topic 606). WGP adopted Topic 606 on January 1, 2018, using the modified retrospective method applied to WES contracts that were not completed as of January 1, 2018. The cumulative effect adjustment that was recognized in the opening balance of equity and partners’ capital was a decrease of $44.4 million . The comparative historical financial information has not been adjusted and continues to be reported under Revenue Recognition (Topic 605) (“Topic 605”). Effective January 1, 2018, WGP changed its accounting policy for revenue recognition as detailed below: • Fee-based gathering / processing. Under Topic 605, fee revenues were recognized based on the rate in effect for the month of service, even when certain fees were charged on an upfront or limited-term basis. In addition, deficiency fees were charged and recognized only when the customer did not meet the specified delivery minimums for the completed performance period. Under Topic 606, (i) revenues continue to be recognized based on the rate in effect when the fee is either the same rate per unit over the contract term or when the fee escalates and the escalation factor approximates inflation, (ii) deficiency fees are estimated and recognized during the performance period as the services are performed for the customer’s delivered volumes, and (iii) timing differences between Service revenues – fee based recognized and amounts billed to customers are recognized as contract assets or contract liabilities, as appropriate, which results in a change in the timing of revenue and changes to net income as a result of the revenue contract’s consideration provisions. In addition, under Topic 606, revenue associated with upfront or limited-term fees is recognized over the expected period of customer benefit, which is generally the life of the related properties. These revenues also include revenues earned for marketing services performed on behalf of WES’s customers, and the expense associated with these marketing activities is recognized in cost of product expense, resulting in no impact to operating income. • Cost of service rate adjustments. Under Topic 605, revenue was recognized based on the amounts billed to customers each period as Service revenues – fee based. Under Topic 606, fixed minimum volume commitment demand fees and variable fees that are also billed on these minimum volumes are recognized as Service revenues – fee based on a consistent per-unit rate over the term of the contract. Annual adjustments are made to the cost of service rates charged to customers, and, as a result, a cumulative catch-up revenue adjustment related to the services already provided under the contract may be recorded in future periods, with revenues for the remaining term of the contract recognized on a consistent per-unit rate. Fees received on volumes in excess of the minimum volumes are recognized as Service revenues – fee based as service is provided to the customer based on the billing rate in effect for the performance period. This revenue recognition timing does not affect billings to customers, and differences between amounts billed and revenue recognized are recorded as contract assets or liabilities, as appropriate. • Aid in construction. Under Topic 605, aid in construction reimbursements were reflected as a reduction to property, plant and equipment upon receipt (and a reduction to capital expenditures). Under Topic 606, reimbursement of capital costs received from customers is reflected as a contract liability (deferred revenue) upon receipt. The contract liability is amortized to Service revenues – fee based over the expected period of customer benefit, which is generally the life of the related properties. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) • Percent-of-proceeds gathering / processing. Under Topic 605, WES recognized cost of product expense when the product was purchased from a producer to whom it provides services, and WES recognized revenue when the product was sold to Anadarko or a third party. Under Topic 606, in some instances, where all or a percentage of the proceeds from the sale must be returned to the producer, the net margin from the purchase and sale transactions is presented net within Service revenues – product based because WES is acting as the producer’s agent in the product sale. • Noncash consideration - keep-whole and percent-of-product agreements. Under Topic 605, WES recognized revenues only upon the sale of the related products. Under Topic 606, (i) Service revenues – product based is recognized for the products received as noncash consideration in exchange for the services provided, with the keep-whole noncash consideration value based on the net value of the NGLs over the replacement residue gas cost, and (ii) product sales revenue is recognized, along with cost of product expense related to the sale, when the product is sold to Anadarko or a third party. When the product is sold to Anadarko, Anadarko is acting as WES’s agent in the product sale and WES recognizes revenue, along with cost of product expense related to the sale, based on the Anadarko sales price to the third party, resulting in no impact to operating income. • Wellhead purchase / sale incorporated into gathering / processing. Under Topic 605, the natural gas purchase cost was recognized as cost of product expense and any specified gathering or processing fees charged to the producer were recognized as revenues. Under Topic 606, the fees charged to the producer under this contract type are recognized as adjustments to the amount recognized in cost of product expense instead of revenues when such fees relate to services performed after control of the product transfers to WES. The following tables summarize the impact of adopting Topic 606 on the impacted line items within the consolidated statements of operations and the consolidated balance sheet. The differences between revenue as reported following Topic 606 and revenue as it would have been reported under Topic 605 are due to the changes described above. Three Months Ended thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Revenues Service revenues – fee based $ 409,106 $ 396,161 $ 12,945 Service revenues – product based 22,735 — 22,735 Product sales 75,150 366,603 (291,453 ) Expenses Cost of product 105,966 353,641 (247,675 ) Operation and maintenance 111,359 111,327 32 Depreciation and amortization 82,553 81,824 729 Income tax (benefit) expense 1,517 1,580 (63 ) Net income (loss) attributable to noncontrolling interests 47,203 40,471 6,732 Net income (loss) attributable to Western Gas Equity Partners, LP 107,474 123,002 (15,528 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Nine Months Ended thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Revenues Service revenues – fee based $ 1,146,099 $ 1,096,708 $ 49,391 Service revenues – product based 67,433 — 67,433 Product sales 217,738 978,127 (760,389 ) Expenses Cost of product 303,518 940,936 (637,418 ) Operation and maintenance 300,266 300,098 168 Depreciation and amortization 238,187 236,102 2,085 Impairments 152,708 152,663 45 Income tax (benefit) expense 3,301 3,361 (60 ) Net income (loss) attributable to noncontrolling interests 63,669 89,339 (25,670 ) Net income (loss) attributable to Western Gas Equity Partners, LP 276,059 258,774 17,285 September 30, 2018 thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Assets Other current assets $ 26,119 $ 23,371 $ 2,748 Net property, plant and equipment 6,418,634 6,320,225 98,409 Other assets 14,057 13,894 163 Liabilities Accrued liabilities 114,504 106,810 7,694 Deferred income taxes 10,285 10,519 (234 ) Other liabilities 141,957 2,781 139,176 Equity and partners’ capital Total equity and partners’ capital 3,616,640 3,661,956 (45,316 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) New accounting standards issued but not yet adopted. ASU 2016-02, Leases (Topic 842) requires lessees to recognize a lease liability and a right-of-use (“ROU”) asset for all leases, including operating leases, with a term greater than 12 months on the balance sheet. This ASU modifies the definition of a lease and outlines the recognition, measurement, presentation, and disclosure of leasing arrangements by both lessees and lessors. WGP plans to make certain elections allowing WGP not to reassess contracts that commenced prior to adoption, to continue applying WES’s current accounting policy for existing or expired land easements and not to recognize ROU assets or lease liabilities for short-term leases. WGP continues to review contracts in WES’s portfolio of leased assets to assess the impact of adopting this ASU, which is expected to primarily impact other assets and other long-term liabilities. To facilitate compliance with this ASU, WES expects to implement new accounting software and complete the evaluation of its systems, processes and internal controls by the end of 2018. WGP will adopt this ASU on January 1, 2019, using a modified retrospective approach. As permitted by ASU 2018-11, Leases (Topic 842): Targeted Improvements , WGP does not expect to adjust comparative period financial statements.
Revenue and cost of product policy	Revenue and cost of product. Upon adoption of the new revenue recognition standard on January 1, 2018 (discussed in Recently adopted accounting standards ), WGP changed its accounting policy for revenue recognition as described below. WES provides gathering, processing, treating, transportation and disposal services pursuant to a variety of contracts. Under these arrangements, WES receives fees and/or retains a percentage of products or a percentage of the proceeds from the sale of the customer’s products. These revenues are included in Service revenues and Product sales in the consolidated statements of operations. Payment is generally received from the customer in the month following the service or delivery of the product. Contracts with customers generally have initial terms ranging from 5 to 10 years. Service revenues – fee based is recognized for fee-based contracts in the month of service based on the volumes delivered by the customer. Producers’ wells or production facilities are connected to WES’s gathering systems for gathering, processing, treating, transportation and disposal of natural gas, NGLs, condensate, crude oil and produced water, as applicable. Revenues are valued based on the rate in effect for the month of service when the fee is either the same rate per unit over the contract term or when the fee escalates and the escalation factor approximates inflation. Deficiency fees charged to customers that do not meet their minimum delivery requirements are recognized as services are performed based on an estimate of the fees that will be billed upon completion of the performance period. Because of its significant upfront capital investment, WES may charge additional service fees to customers for only a portion of the contract term (i.e., for the first year of a contract or until reaching a volume threshold), and these fees are recognized as revenue over the expected period of customer benefit, which is generally the life of the related properties. WES also recognizes revenue and cost of product expense from marketing services performed on behalf of its customers by Anadarko. WES also receives Service revenues – fee based from contracts that have minimum volume commitment demand fees and fees that require periodic rate redeterminations based upon the related facility cost of service. These fees include fixed and variable consideration that are recognized on a consistent per-unit rate over the term of the contract. Annual adjustments are made to the cost of service rates charged to customers, and a cumulative catch-up revenue adjustment related to services already provided to the minimum volumes under the contract may be recorded in future periods, with revenues for the remaining term of the contract recognized on a consistent per-unit rate. Service revenues – product based includes service revenues from percent-of-proceeds gathering and processing contracts that are recognized net of the cost of product for purchases from WES’s customers since it is acting as the agent in the product sale. Keep-whole and percent-of-product agreements result in Service revenues – product based being recognized when the natural gas and/or NGLs are received from the customer as noncash consideration for the services provided. Noncash consideration for these services is valued at the time the services are provided. Revenue from product sales is also recognized, along with the cost of product expense related to the sale, when the product received as noncash consideration is sold to either Anadarko or a third party. When the product is sold to Anadarko, Anadarko is acting as WES’s agent in the product sale, with WES recognizing revenue and related cost of product expense associated with these marketing activities based on the Anadarko sales price to the third party. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) WES also purchases natural gas volumes from producers at the wellhead or from a production facility, typically at an index price, and charges the producer fees associated with the downstream gathering and processing services. When the fees relate to services performed after control of the product has transferred to WES, the fees are treated as a reduction of the purchase cost. Revenue from product sales is recognized, along with cost of product expense related to the sale, when the purchased product is sold to either Anadarko or a third party. WES receives aid in construction reimbursements for certain capital costs necessary to provide services to customers (i.e., connection costs, etc.) under certain service contracts. Aid in construction reimbursements are reflected as a contract liability upon receipt and amortized to Service revenues – fee based over the expected period of customer benefit, which is generally the life of the related properties.
Net income (loss) per common unit policy	Net income (loss) per common unit. For WGP, basic net income (loss) per common unit is calculated by dividing the limited partners’ interest in net income (loss) by the weighted-average number of common units outstanding during the period. Dilutive net income (loss) per common unit is calculated by dividing the limited partners’ interest in net income (loss) adjusted for distributions on the WES Series A Preferred units and a reallocation of the limited partners’ interest in net income (loss) assuming, prior to the actual conversion, conversion of the WES Series A Preferred units into WES common units, by the weighted-average number of WGP common units outstanding during the period. As of May 2, 2017, all WES Series A Preferred units were converted into WES common units on a one-for-one basis. The impact of the Series A Preferred units assuming, prior to the actual conversion, conversion to WES common units would be anti-dilutive for the nine months ended September 30, 2017 . Net income (loss) per common unit is calculated assuming that cash distributions are equal to the net income attributable to WGP. Net income (loss) attributable to the WES assets (as defined in Note 1 ) acquired from Anadarko for periods prior to WES’s acquisition of the WES assets is not allocated to the limited partners when calculating net income (loss) per common unit. Net income equal to the amount of available cash (as defined by WGP’s partnership agreement) is allocated to WGP common unitholders consistent with actual cash distributions.

Description of Business and B_3

Description of Business and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Assets and Investments Table	As of September 30, 2018 , WES’s assets and investments consisted of the following: Owned and Operated Operated Interests Non-Operated Interests Equity Interests Gathering systems (1) 12 3 3 2 Treating facilities 19 3 — 3 Natural gas processing plants/trains 20 4 — 2 NGL pipelines 2 — — 3 Natural gas pipelines 5 — — — Oil pipelines — 1 — 2 (1) Includes the DBM water systems.
Ownership Interests and Method of Consolidation Table	The following table outlines WES’s ownership interests and the accounting method of consolidation used in WES’s consolidated financial statements for entities not wholly owned: Percentage Interest Equity investments (1) Fort Union 14.81 % White Cliffs 10 % Rendezvous 22 % Mont Belvieu JV 25 % TEP 20 % TEG 20 % FRP 33.33 % Whitethorn 20 % Cactus II 15 % Proportionate consolidation (2) Marcellus Interest systems 33.75 % Newcastle system 50 % Springfield system 50.1 % Full consolidation Chipeta (3) 75 % (1) Investments in non-controlled entities over which WES exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to WES’s share of average throughput for these investments. (2) WGP proportionately consolidates WES’s associated share of the assets, liabilities, revenues and expenses attributable to these assets. (3) The 25% interest in Chipeta Processing LLC (“Chipeta”) held by a third-party member is reflected within noncontrolling interests in the consolidated financial statements, in addition to the noncontrolling interests noted below.
Impact of New Accounting Pronouncement Tables	The following tables summarize the impact of adopting Topic 606 on the impacted line items within the consolidated statements of operations and the consolidated balance sheet. The differences between revenue as reported following Topic 606 and revenue as it would have been reported under Topic 605 are due to the changes described above. Three Months Ended thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Revenues Service revenues – fee based $ 409,106 $ 396,161 $ 12,945 Service revenues – product based 22,735 — 22,735 Product sales 75,150 366,603 (291,453 ) Expenses Cost of product 105,966 353,641 (247,675 ) Operation and maintenance 111,359 111,327 32 Depreciation and amortization 82,553 81,824 729 Income tax (benefit) expense 1,517 1,580 (63 ) Net income (loss) attributable to noncontrolling interests 47,203 40,471 6,732 Net income (loss) attributable to Western Gas Equity Partners, LP 107,474 123,002 (15,528 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Nine Months Ended thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Revenues Service revenues – fee based $ 1,146,099 $ 1,096,708 $ 49,391 Service revenues – product based 67,433 — 67,433 Product sales 217,738 978,127 (760,389 ) Expenses Cost of product 303,518 940,936 (637,418 ) Operation and maintenance 300,266 300,098 168 Depreciation and amortization 238,187 236,102 2,085 Impairments 152,708 152,663 45 Income tax (benefit) expense 3,301 3,361 (60 ) Net income (loss) attributable to noncontrolling interests 63,669 89,339 (25,670 ) Net income (loss) attributable to Western Gas Equity Partners, LP 276,059 258,774 17,285 September 30, 2018 thousands As Reported Without Adoption of Topic 606 Effect of Change Increase / (Decrease) Assets Other current assets $ 26,119 $ 23,371 $ 2,748 Net property, plant and equipment 6,418,634 6,320,225 98,409 Other assets 14,057 13,894 163 Liabilities Accrued liabilities 114,504 106,810 7,694 Deferred income taxes 10,285 10,519 (234 ) Other liabilities 141,957 2,781 139,176 Equity and partners’ capital Total equity and partners’ capital 3,616,640 3,661,956 (45,316 )

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Summary of Revenue from Contracts with Customers Table	The following table summarizes revenue from contracts with customers: thousands Three Months Ended Nine Months Ended Revenue from customers Service revenues – fee based $ 409,106 $ 1,146,099 Service revenues – product based 22,735 67,433 Product sales 78,887 224,089 Total revenue from customers 510,728 1,437,621 Revenue from other than customers Net gains (losses) on commodity price swap agreements (3,737 ) (6,351 ) Other 771 1,213 Total revenues and other $ 507,762 $ 1,432,483
Contract Assets and Liabilities Activity Tables	The following table summarizes the current period activity related to contract liabilities from contracts with customers: thousands Balance at December 31, 2017 $ — Cumulative effect of adopting Topic 606 120,717 Cash received or receivable, excluding revenues recognized during the period (1) 37,340 Revenues recognized during the period that were included in the adoption effect (2) (10,850 ) Balance at September 30, 2018 $ 147,207 Contract liabilities at September 30, 2018 Accrued liabilities $ 8,031 Other liabilities 139,176 Total contract liabilities from contracts with customers $ 147,207 (1) Includes $(3.7) million for the three months ended September 30, 2018 . (2) Includes $(8.8) million for the three months ended September 30, 2018 , of which $(7.5) million was from a performance obligation satisfied in a previous period related to the arbitration against SWEPI LP (see Note 11 ). The following table summarizes the current period activity related to contract assets from contracts with customers: thousands Balance at December 31, 2017 $ — Cumulative effect of adopting Topic 606 5,129 Amounts transferred to Accounts receivable, net from contract assets recognized in the adoption effect (1) (4,358 ) Additional estimated revenues recognized (2) 2,140 Balance at September 30, 2018 $ 2,911 Contract assets at September 30, 2018 Other current assets $ 2,748 Other assets 163 Total contract assets from contracts with customers $ 2,911 (1) Includes $(1.7) million for the three months ended September 30, 2018 . (2) Includes $(5.0) million for the three months ended September 30, 2018 .
Expected Revenue Recognition from Satisfaction of Performance Obligations Table	Therefore, the following table represents only a small portion of expected future revenues from existing contracts as most future revenues from customers are dependent on future variable customer volumes and in some cases variable commodity prices for those volumes. thousands Remainder of 2018 $ 124,395 2019 480,211 2020 545,223 2021 524,810 2022 528,900 Thereafter 2,191,811 Total $ 4,395,350

Partnership Distributions (Tabl

Partnership Distributions (Tables)	9 Months Ended
	Sep. 30, 2018
Distribution Made to Limited Partner [Line Items]
Cash Distributions Tables	The Board of Directors of WGP GP (the “Board of Directors”) declared the following cash distributions to WGP unitholders for the periods presented: thousands except per-unit amounts Quarters Ended Total Quarterly Distribution per Unit Total Quarterly Cash Distribution Date of Distribution 2017 March 31 $ 0.49125 $ 107,549 May 2017 June 30 0.52750 115,487 August 2017 September 30 0.53750 117,677 November 2017 December 31 0.54875 120,140 February 2018 2018 March 31 $ 0.56875 $ 124,518 May 2018 June 30 0.58250 127,531 August 2018 September 30 (1) 0.59500 130,268 November 2018 (1) The Board of Directors declared a cash distribution to WGP unitholders for the third quarter of 2018 of $0.59500 per unit, or $130.3 million in aggregate. The cash distribution is payable on November 21, 2018 , to WGP unitholders of record at the close of business on October 31, 2018 .
Western Gas Partners, LP [Member]
Distribution Made to Limited Partner [Line Items]
Cash Distributions Tables	The Board of Directors of WES GP declared the following cash distributions to WES’s common and general partner unitholders for the periods presented: thousands except per-unit amounts Quarters Ended Total Quarterly Total Quarterly Date of 2017 March 31 $ 0.875 $ 188,753 May 2017 June 30 0.890 207,491 August 2017 September 30 0.905 212,038 November 2017 December 31 0.920 216,586 February 2018 2018 March 31 $ 0.935 $ 221,133 May 2018 June 30 0.950 225,691 August 2018 September 30 (1) 0.965 230,239 November 2018 (1) The Board of Directors of WES GP declared a cash distribution to WES unitholders for the third quarter of 2018 of $0.965 per unit, or $230.2 million in aggregate, including incentive distributions, but excluding distributions on WES Class C units (see WES Class C unit distributions below). The cash distribution is payable on November 13, 2018 , to WES unitholders of record at the close of business on October 31, 2018 .

Equity and Partners' Capital (T

Equity and Partners' Capital (Tables)	9 Months Ended
	Sep. 30, 2018
Partners' Capital Notes [Abstract]
Partnership Interests Table	The following table summarizes WES’s units issued during the nine months ended September 30, 2018 : WES Common Units WES Class C Units WES General Partner Units Total Balance at December 31, 2017 152,602,105 13,243,883 2,583,068 168,429,056 PIK Class C units — 801,546 — 801,546 Long-Term Incentive Plan award vestings 7,180 — — 7,180 Balance at September 30, 2018 152,609,285 14,045,429 2,583,068 169,237,782

Transactions with Affiliates (T

Transactions with Affiliates (Tables)	9 Months Ended
	Sep. 30, 2018
Related Party Fees and Other Arrangements, Limited Liability Company (LLC) or Limited Partnership (LP) [Abstract]
Commodity Price Swap Agreements Tables	The tables below summarize the swap prices compared to the forward market prices: DJ Basin Complex per barrel except natural gas 2017 - 2018 Swap Prices 2017 Market Prices (1) 2018 Market Prices (1) Ethane $ 18.41 $ 5.09 $ 5.41 Propane 47.08 18.85 28.72 Isobutane 62.09 26.83 32.92 Normal butane 54.62 26.20 32.71 Natural gasoline 72.88 41.84 48.04 Condensate 76.47 45.40 49.36 Natural gas (per MMBtu) 5.96 3.05 2.21 MGR Assets per barrel except natural gas 2017 - 2018 Swap Prices 2017 Market Prices (1) 2018 Market Prices (1) Ethane $ 23.11 $ 4.08 $ 2.52 Propane 52.90 19.24 25.83 Isobutane 73.89 25.79 30.03 Normal butane 64.93 25.16 29.82 Natural gasoline 81.68 45.01 47.25 Condensate 81.68 53.55 56.76 Natural gas (per MMBtu) 4.87 3.05 2.21 (1) Represents the New York Mercantile Exchange forward strip price as of December 1, 2016, and December 20, 2017 , for the 2017 Market Prices and 2018 Market Prices, respectively, adjusted for product specification, location, basis and, in the case of NGLs, transportation and fractionation costs.
Related Party Transactions Tables	The following table summarizes WES’s purchases from Anadarko of pipe and equipment: Nine Months Ended September 30, thousands 2018 2017 Cash consideration $ 254 $ 3,910 Net carrying value (254 ) (5,283 ) Partners’ capital adjustment $ — $ (1,373 ) The following table summarizes material affiliate transactions: Three Months Ended Nine Months Ended thousands 2018 2017 2018 2017 Revenues and other (1) $ 274,514 $ 351,127 $ 766,179 $ 982,595 Equity income, net – affiliates (1) 43,110 21,519 102,752 62,708 Cost of product (1) 46,971 22,902 131,428 60,497 Operation and maintenance (2) 25,145 18,110 68,830 53,661 General and administrative (3) 11,780 10,414 35,000 29,637 Operating expenses 83,896 51,426 235,258 143,795 Interest income (4) 4,225 4,225 12,675 12,675 Interest expense (5) — — — 71 Settlement of the Deferred purchase price obligation – Anadarko (6) — — — (37,346 ) Distributions to WGP unitholders (7) 99,247 94,205 298,818 264,533 Distributions to WES unitholders (8) 1,911 1,790 5,642 5,280 Above-market component of swap agreements with Anadarko 12,601 18,049 40,722 46,719 (1) Represents amounts earned or incurred on and subsequent to the date of the 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. (2) 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. (3) Represents general and administrative expense incurred on and subsequent to the date of the 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 Anadarko Incentive Plan within this Note 6 ) and amounts charged by Anadarko under the WGP and WES omnibus agreements. (4) Represents interest income recognized on the note receivable from Anadarko. (5) Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10 ) . (6) Represents the cash payment to Anadarko for the settlement of the Deferred purchase price obligation - Anadarko (see Note 3 ). (7) Represents distributions paid under WGP’s partnership agreement (see Note 4 and Note 5 ). (8) Represents distributions paid to other subsidiaries of Anadarko under WES’s partnership agreement (see Note 4 and Note 5 ).

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Table	A summary of the historical cost of property, plant and equipment is as follows: thousands Estimated Useful Life September 30, December 31, Land n/a $ 4,653 $ 4,450 Gathering systems and processing complexes 3 to 47 years 7,883,265 7,113,114 Pipelines and equipment 15 to 45 years 137,769 137,644 Assets under construction n/a 856,092 579,501 Other 3 to 40 years 30,976 29,826 Total property, plant and equipment 8,912,755 7,864,535 Less accumulated depreciation 2,494,121 2,133,644 Net property, plant and equipment $ 6,418,634 $ 5,730,891

Equity Investments (Tables)

Equity Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments Table	The following table presents the activity in WES’s equity investments for the nine months ended September 30, 2018 : thousands Fort White Rendezvous Mont TEFR Interests Whitethorn Cactus II Total Balance at December 31, 2017 $ 7,030 $ 44,945 $ 42,528 $ 110,299 $ 361,409 $ — $ — $ 566,211 Acquisitions — — — — — 150,563 11,295 161,858 Investment earnings (loss), net of amortization (892 ) 8,547 635 22,916 47,736 23,810 — 102,752 Contributions — 1,278 — — 24,680 7,069 34,436 67,463 Capitalized interest — — — — — — 516 516 Distributions (194 ) (8,111 ) (2,091 ) (22,945 ) (43,989 ) (16,497 ) — (93,827 ) Distributions in excess of cumulative earnings (1) (2,889 ) (3,109 ) (2,015 ) (3,305 ) (6,779 ) — — (18,097 ) Balance at September 30, 2018 $ 3,055 $ 43,550 $ 39,057 $ 106,965 $ 383,057 $ 164,945 $ 46,247 $ 786,876 (1) Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, are calculated on an individual investment basis.

Components of Working Capital (

Components of Working Capital (Tables)	9 Months Ended
	Sep. 30, 2018
Components Of Working Capital [Abstract]
Accounts Receivable, Net Table	A summary of accounts receivable, net is as follows: thousands September 30, 2018 December 31, 2017 Trade receivables, net $ 224,719 $ 160,194 Other receivables, net 168 45 Total accounts receivable, net $ 224,887 $ 160,239
Other Current Assets Table	A summary of other current assets is as follows: thousands September 30, 2018 December 31, 2017 Natural gas liquids inventory $ 11,212 $ 10,788 Imbalance receivables 3,829 1,640 Prepaid insurance 3,203 2,955 Contract assets 2,748 — Other 5,127 — Total other current assets $ 26,119 $ 15,383
Accrued Liabilities Table	A summary of accrued liabilities is as follows: thousands September 30, 2018 December 31, 2017 Accrued interest expense $ 54,556 $ 40,646 Short-term asset retirement obligations (1) 42,872 2,304 Short-term remediation and reclamation obligations 833 833 Income taxes payable 247 2,495 Contract liabilities 8,031 — Other 7,965 1,714 Total accrued liabilities $ 114,504 $ 47,992 (1) As of September 30, 2018 , includes $40.2 million of short-term liabilities incurred during the second quarter of 2018 related to the shutdowns at the Third Creek and Kitty Draw gathering systems. See Note 1 for further information.

Debt and Interest Expense (Tabl

Debt and Interest Expense (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Instruments [Abstract]
Debt Outstanding and Debt Activity Tables	The following table presents WES and WGP’s outstanding debt: September 30, 2018 December 31, 2017 thousands Principal Carrying Value Fair Value (1) Principal Carrying Value Fair Value (1) Short-term debt WGP RCF $ 28,000 $ 28,000 $ 28,000 $ — $ — $ — WGP long-term debt WGP RCF $ — $ — $ — $ 28,000 $ 28,000 $ 28,000 WES long-term debt 2.600% Senior Notes due 2018 — — — 350,000 349,684 350,631 5.375% Senior Notes due 2021 500,000 496,669 517,160 500,000 495,815 530,647 4.000% Senior Notes due 2022 670,000 669,020 668,198 670,000 668,849 684,043 3.950% Senior Notes due 2025 500,000 492,596 478,470 500,000 491,885 500,885 4.650% Senior Notes due 2026 500,000 495,592 492,502 500,000 495,245 520,144 4.500% Senior Notes due 2028 400,000 394,514 384,964 — — — 4.750% Senior Notes due 2028 400,000 395,806 391,532 — — — 5.450% Senior Notes due 2044 600,000 593,319 565,485 600,000 593,234 637,827 5.300% Senior Notes due 2048 700,000 686,601 645,643 — — — 5.500% Senior Notes due 2048 350,000 342,347 331,981 — — — WES RCF — — — 370,000 370,000 370,000 Total long-term debt $ 4,620,000 $ 4,566,464 $ 4,475,935 $ 3,518,000 $ 3,492,712 $ 3,622,177 (1) Fair value is measured using the market approach and Level 2 inputs. 10. DEBT AND INTEREST EXPENSE (CONTINUED) Debt activity. The following table presents WES and WGP’s debt activity for the nine months ended September 30, 2018 : thousands Carrying Value Balance at December 31, 2017 $ 3,492,712 WES RCF borrowings 320,000 Issuance of 4.500% Senior Notes due 2028 400,000 Issuance of 5.300% Senior Notes due 2048 700,000 Issuance of 4.750% Senior Notes due 2028 400,000 Issuance of 5.500% Senior Notes due 2048 350,000 Repayment of 2.600% Senior Notes due 2018 (350,000 ) Repayments of WES RCF borrowings (690,000 ) Other (28,248 ) Balance at September 30, 2018 $ 4,594,464
Interest Expense Table	The following table summarizes the amounts included in interest expense: Three Months Ended Nine Months Ended thousands 2018 2017 2018 2017 Third parties Long-term and short-term debt $ (53,229 ) $ (36,223 ) $ (143,436 ) $ (106,412 ) Amortization of debt issuance costs and commitment fees (2,054 ) (2,009 ) (6,955 ) (5,955 ) Capitalized interest 6,967 2,115 17,032 3,991 Total interest expense – third parties (48,316 ) (36,117 ) (133,359 ) (108,376 ) Affiliates Deferred purchase price obligation – Anadarko (1) — — — (71 ) Total interest expense – affiliates — — — (71 ) Interest expense $ (48,316 ) $ (36,117 ) $ (133,359 ) $ (108,447 ) (1) See Note 3 for a discussion of the Deferred purchase price obligation - Anadarko.

Description of Business and B_4

Description of Business and Basis of Presentation - Assets and Investments Table (Details) - Western Gas Partners, LP [Member]	Sep. 30, 2018unit
Owned and Operated [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	12	[1]
Owned and Operated [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	19
Owned and Operated [Member] | Natural Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	20
Owned and Operated [Member] | Natural Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	2
Owned and Operated [Member] | Natural Gas Pipelines [Member]
Assets [Line Items]
Assets, number of units	5
Operated Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	3	[1]
Operated Interests [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	3
Operated Interests [Member] | Natural Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	4
Operated Interests [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	1
Non-Operated Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	3	[1]
Equity Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2	[1]
Equity Interests [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	3
Equity Interests [Member] | Natural Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	2
Equity Interests [Member] | Natural Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	3
Equity Interests [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	2
[1]	Includes the DBM water systems.

Description of Business and B_5

Description of Business and Basis of Presentation - Ownership Interests and Method of Consolidation Table (Details)	9 Months Ended
	Sep. 30, 2018
Chipeta [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Ownership interest by noncontrolling interest owner	25.00%
Western Gas Partners, LP [Member] | Equity Investments [Member] | Fort Union [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	14.81%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | White Cliffs [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	10.00%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Rendezvous [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	22.00%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Mont Belvieu JV [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	25.00%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Texas Express Pipeline [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	20.00%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Texas Express Gathering [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	20.00%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Front Range Pipeline [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	33.33%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Whitethorn [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	20.00%	[1]
Western Gas Partners, LP [Member] | Equity Investments [Member] | Cactus II [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	15.00%	[1]
Western Gas Partners, LP [Member] | Proportionate Consolidation [Member] | Marcellus Interest Systems [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	33.75%	[2]
Western Gas Partners, LP [Member] | Proportionate Consolidation [Member] | Newcastle System [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	50.00%	[2]
Western Gas Partners, LP [Member] | Proportionate Consolidation [Member] | Springfield System [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	50.10%	[2]
Western Gas Partners, LP [Member] | Full Consolidation [Member] | Chipeta [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	75.00%	[3]
[1]	Investments in non-controlled entities over which WES exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to WES’s share of average throughput for these investments.
[2]	WGP proportionately consolidates WES’s associated share of the assets, liabilities, revenues and expenses attributable to these assets.
[3]	The 25% interest in Chipeta Processing LLC (“Chipeta”) held by a third-party member is reflected within noncontrolling interests in the consolidated financial statements, in addition to the noncontrolling interests noted below.

Description of Business and B_6

Description of Business and Basis of Presentation - Impact of New Accounting Pronouncement - Statements of Operations Table (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenues
Revenues and other		$ 507,762	$ 574,695	$ 1,432,483	$ 1,616,338
Expenses
Cost of product	[1]	105,966	239,223	303,518	631,859
Operation and maintenance	[1]	111,359	79,536	300,266	229,444
Depreciation and amortization		82,553	72,539	238,187	216,272
Impairments		25,317	2,159	152,708	170,079	$ 178,400
Income tax (benefit) expense		1,517	510	3,301	4,905
Net income (loss) attributable to noncontrolling interests		47,203	50,399	63,669	146,529
Net income (loss) attributable to Western Gas Equity Partners, LP		107,474	$ 96,202	276,059	$ 277,086
Service Revenues - Fee Based [Member]
Revenues
Revenues and other		409,106		1,146,099
Service Revenues - Product Based [Member]
Revenues
Revenues and other		22,735		67,433
Product Sales [Member]
Revenues
Revenues and other		75,150		217,738
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member]
Expenses
Cost of product		353,641		940,936
Operation and maintenance		111,327		300,098
Depreciation and amortization		81,824		236,102
Impairments				152,663
Income tax (benefit) expense		1,580		3,361
Net income (loss) attributable to noncontrolling interests		40,471		89,339
Net income (loss) attributable to Western Gas Equity Partners, LP		123,002		258,774
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Service Revenues - Fee Based [Member]
Revenues
Revenues and other		396,161		1,096,708
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Service Revenues - Product Based [Member]
Revenues
Revenues and other		0		0
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Product Sales [Member]
Revenues
Revenues and other		366,603		978,127
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase / (Decrease) [Member]
Expenses
Cost of product		(247,675)		(637,418)
Operation and maintenance		32		168
Depreciation and amortization		729		2,085
Impairments				45
Income tax (benefit) expense		(63)		(60)
Net income (loss) attributable to noncontrolling interests		6,732		(25,670)
Net income (loss) attributable to Western Gas Equity Partners, LP		(15,528)		17,285
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase / (Decrease) [Member] | Service Revenues - Fee Based [Member]
Revenues
Revenues and other		12,945		49,391
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase / (Decrease) [Member] | Service Revenues - Product Based [Member]
Revenues
Revenues and other		22,735		67,433
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase / (Decrease) [Member] | Product Sales [Member]
Revenues
Revenues and other		$ (291,453)		$ (760,389)
[1]	Cost of product includes product purchases from affiliates (as defined in Note 1) of $47.0 million and $131.4 million for the three and nine months ended September 30, 2018, respectively, and $22.9 million and $60.5 million for the three and nine months ended September 30, 2017, respectively. Operation and maintenance includes charges from affiliates of $25.1 million and $68.8 million for the three and nine months ended September 30, 2018, respectively, and $18.1 million and $53.7 million for the three and nine months ended September 30, 2017, respectively. General and administrative includes charges from affiliates of $11.8 million and $35.0 million for the three and nine months ended September 30, 2018, respectively, and $10.4 million and $29.6 million for the three and nine months ended September 30, 2017, respectively. See Note 6.

Description of Business and B_7

Description of Business and Basis of Presentation - Impact of New Accounting Pronouncement - Balance Sheet Table (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Assets
Other current assets	[1]	$ 26,119	$ 15,383
Net property, plant and equipment		6,418,634	5,730,891
Other assets		14,057	12,570
Liabilities
Accrued liabilities	[2]	114,504	47,992
Deferred income taxes		10,285	7,409
Other liabilities	[3]	141,957	3,491
Equity and partners' capital
Total equity and partners' capital		3,616,640	$ 3,944,879
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member]
Assets
Other current assets		23,371
Net property, plant and equipment		6,320,225
Other assets		13,894
Liabilities
Accrued liabilities		106,810
Deferred income taxes		10,519
Other liabilities		2,781
Equity and partners' capital
Total equity and partners' capital		3,661,956
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase / (Decrease) [Member]
Assets
Other current assets		2,748
Net property, plant and equipment		98,409
Other assets		163
Liabilities
Accrued liabilities		7,694
Deferred income taxes		(234)
Other liabilities		139,176
Equity and partners' capital
Total equity and partners' capital		$ (45,316)
[1]	Other current assets includes affiliate amounts of $1.4 million and zero as of September 30, 2018, and December 31, 2017, respectively.
[2]	Accrued liabilities includes affiliate amounts of $2.3 million and $0.2 million as of September 30, 2018, and December 31, 2017, respectively.
[3]	Other liabilities includes affiliate amounts of $50.2 million and $0.7 million as of September 30, 2018, and December 31, 2017, respectively.

Description of Business and B_8

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($)		3 Months Ended		6 Months Ended	9 Months Ended				12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018		Sep. 30, 2017		Dec. 31, 2017	Jan. 01, 2018	May 31, 2008
Revenues and other		$ 507,762,000	$ 574,695,000		$ 1,432,483,000		$ 1,616,338,000
Cost of product	[1]	105,966,000	239,223,000		303,518,000		631,859,000
Note receivable - Anadarko		260,000,000			260,000,000				$ 260,000,000
Impairments		25,317,000	2,159,000		152,708,000		170,079,000		$ 178,400,000
Loss on divestiture and other, net	[2]	(65,000)	(72,000)		(351,000)	[3]	(135,017,000)	[3]
Proceeds from property insurance claims					0		22,977,000
Cumulative effect of accounting change	[4]	(44,379,000)			(44,379,000)
Accounting Standards Update 2014-09 [Member]
Cumulative effect of accounting change										$ (44,379,000)
Service Revenues - Fee Based [Member]
Revenues and other		409,106,000			1,146,099,000
Product Sales [Member]
Revenues and other		$ 75,150,000			$ 217,738,000
Chipeta [Member]
Ownership interest by noncontrolling interest owner		25.00%			25.00%
Affiliates [Member]
Revenues and other	[5]	$ 274,514,000	351,127,000		$ 766,179,000		982,595,000
Cost of product	[5]	46,971,000	22,902,000		131,428,000		60,497,000
Affiliates [Member] | Service Revenues - Fee Based [Member]
Revenues and other		204,090,000	157,303,000		582,579,000		484,601,000
Affiliates [Member] | Product Sales [Member]
Revenues and other		69,723,000	$ 185,002,000		$ 182,372,000		489,172,000
Prior Period Adjustment [Member]
Cost of product				$ 51,600,000
Prior Period Adjustment [Member] | Service Revenues - Fee Based [Member]
Revenues and other				39,000,000
Prior Period Adjustment [Member] | Product Sales [Member]
Revenues and other				$ 12,600,000
Western Gas Equity Partners, LP [Member] | Western Gas Partners, LP [Member] | General Partner [Member]
Percentage ownership interest					100.00%
Western Gas Partners, LP [Member] | Maximum [Member]
Contract terms					Payment is generally received from the customer in the month following the service or delivery of the product. Contracts with customers generally have initial terms ranging from 5 to 10 years.
Western Gas Partners, LP [Member] | Kitty Draw and Third Creek Gathering Systems [Member]
Impairments		6,800,000			$ 134,000,000
Western Gas Partners, LP [Member] | Delaware Basin Midstream Complex [Member]
Loss on divestiture and other, net							5,700,000
Proceeds from insurance claims, total							52,900,000
Proceeds from business interruption insurance claims							29,882,000
Proceeds from property insurance claims							$ 22,977,000
Western Gas Partners, LP [Member] | Affiliates [Member]
Note receivable - Anadarko		260,000,000			260,000,000						$ 260,000,000
Western Gas Partners, LP [Member] | Affiliates [Member] | Product Sales [Member] | Kitty Draw and Third Creek Gathering Systems [Member]
Revenues and other		$ 0			$ (10,900,000)
Western Gas Partners, LP [Member] | Other Subsidiaries of Anadarko [Member]
WES common units issued					2,011,380
[1]	Cost of product includes product purchases from affiliates (as defined in Note 1) of $47.0 million and $131.4 million for the three and nine months ended September 30, 2018, respectively, and $22.9 million and $60.5 million for the three and nine months ended September 30, 2017, respectively. Operation and maintenance includes charges from affiliates of $25.1 million and $68.8 million for the three and nine months ended September 30, 2018, respectively, and $18.1 million and $53.7 million for the three and nine months ended September 30, 2017, respectively. General and administrative includes charges from affiliates of $11.8 million and $35.0 million for the three and nine months ended September 30, 2018, respectively, and $10.4 million and $29.6 million for the three and nine months ended September 30, 2017, respectively. See Note 6.
[2]	Includes losses related to an incident at the DBM complex for the nine months ended September 30, 2017. See Note 1.
[3]	Includes losses related to an incident at the DBM complex for the nine months ended September 30, 2017. See Note 1.
[4]	See Note 1.
[5]	Represents amounts earned or incurred on and subsequent to the date of the 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.

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Revenue From Contracts With Customers Table (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from customers	$ 510,728		$ 1,437,621
Total revenues and other	507,762	$ 574,695	1,432,483	$ 1,616,338
Service Revenues - Fee Based [Member]
Disaggregation of Revenue [Line Items]
Revenue from customers	409,106		1,146,099
Total revenues and other	409,106		1,146,099
Service Revenues - Product Based [Member]
Disaggregation of Revenue [Line Items]
Revenue from customers	22,735		67,433
Total revenues and other	22,735		67,433
Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from customers	78,887		224,089
Total revenues and other	75,150		217,738
Commodity Price Swap Agreement [Member]
Disaggregation of Revenue [Line Items]
Revenue from other than customers	(3,737)		(6,351)
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from other than customers	$ 771		$ 1,213

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Contract Assets Table (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018		Sep. 30, 2018	Dec. 31, 2017
Change in Contracts with Customer, Asset [Roll Forward]
Balance at December 31, 2017		$ 0
Cumulative effect of adopting Topic 606		5,129
Amounts transferred to Accounts receivable, net from contract assets recognized in the adoption effect	$ (1,700)	(4,358)	[1]
Additional estimated revenues recognized	(5,000)	2,140	[2]
Balance at September 30, 2018	2,911	2,911
Contract assets at September 30, 2018
Other current assets				$ 2,748	$ 0
Other assets				163
Total contract assets from contracts with customers	$ 2,911	$ 0		$ 2,911	$ 0
[1]	Includes $(1.7) million for the three months ended September 30, 2018.
[2]	Includes $(5.0) million for the three months ended September 30, 2018.

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Contract Liabilities Table (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018		Sep. 30, 2018	Dec. 31, 2017
Change in Contracts with Customer, Liability [Roll Forward]
Balance at December 31, 2017		$ 0
Cumulative effect of adopting Topic 606		120,717
Cash received or receivable, excluding revenues recognized during the period	$ (3,700)	37,340	[1]
Revenues recognized during the period that were included in the adoption effect	(8,800)	(10,850)	[2]
Balance at September 30, 2018	147,207	147,207
Contract liabilities at September 30, 2018
Accrued liabilities				$ 8,031	$ 0
Other liabilities				139,176
Total contract liabilities from contracts with customers	$ 147,207	0		$ 147,207	$ 0
Change in Contract with Customer, Asset and Liability [Abstract]
Performance obligation satisfied in previous period		$ (7,500)
[1]	Includes $(3.7) million for the three months ended September 30, 2018.
[2]	Includes $(8.8) million for the three months ended September 30, 2018, of which $(7.5) million was from a performance obligation satisfied in a previous period related to the arbitration against SWEPI LP (see Note 11).

Revenue from Contracts with C_6

Revenue from Contracts with Customers - Expected Revenues Table (Details) $ in Thousands	Sep. 30, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 124,395
Performance obligation expected to be satisfied, expected timing	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 480,211
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 545,223
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 524,810
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 528,900
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 4,395,350
Performance obligation expected to be satisfied, expected timing

Revenue from Contracts with C_7

Revenue from Contracts with Customers - Additional Information (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Revenue from Contracts with Customer [Line Items]
Accounts receivable, net	[1]	$ 224,887	$ 160,239
Customers [Member]
Revenue from Contracts with Customer [Line Items]
Accounts receivable, net		$ 298,200	$ 244,400
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $59.1 million and $36.1 million as of September 30, 2018, and December 31, 2017, respectively.

Acquisitions and Divestitures -

Acquisitions and Divestitures - Additional Information (Details) - USD ($) $ in Thousands		Jun. 27, 2018	Jun. 01, 2018	Mar. 17, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Acquisition, net investment							$ 161,858
Affiliates [Member]
Property, Plant and Equipment [Line Items]
Cash payment							254	$ 3,910
Settlement of the Deferred purchase price obligation - Anadarko	[1]						0	37,346
Deferred Purchase Price Obligation - Anadarko [Member] | Affiliates [Member]
Property, Plant and Equipment [Line Items]
Settlement of the Deferred purchase price obligation - Anadarko	[2]				$ 0	$ 0	$ 0	37,346
Western Gas Partners, LP [Member] | Helper and Clawson Systems [Member]
Property, Plant and Equipment [Line Items]
Gain (loss) on sale of assets								16,300
Western Gas Partners, LP [Member] | Non-Operated Marcellus Interest [Member]
Property, Plant and Equipment [Line Items]
Percentage ownership interest				33.75%
Western Gas Partners, LP [Member] | Whitethorn [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired			20.00%
Acquisition, net investment			$ 150,600
Western Gas Partners, LP [Member] | Cactus II [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired		15.00%
Acquisition, net investment		$ 11,300
Western Gas Partners, LP [Member] | Delaware Basin JV Gathering LLC [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired				50.00%
Percentage ownership interest				50.00%
Cash payment				$ 155,000
Net gain from property exchange								125,700
Western Gas Partners, LP [Member] | Delaware Basin JV Gathering LLC [Member] | Deferred Purchase Price Obligation - Anadarko [Member] | Affiliates [Member]
Property, Plant and Equipment [Line Items]
Settlement of the Deferred purchase price obligation - Anadarko								$ 37,346
[1]	See Note 3.
[2]	Represents the cash payment to Anadarko for the settlement of the Deferred purchase price obligation - Anadarko (see Note 3).

Partnership Distributions - Cas

Partnership Distributions - Cash Distributions Tables (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Sep. 30, 2018		Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.59500	[1]	$ 0.58250	$ 0.56875	$ 0.54875	$ 0.53750	$ 0.52750	$ 0.49125
Total quarterly cash distribution	$ 130,268	[1]	$ 127,531	$ 124,518	$ 120,140	$ 117,677	$ 115,487	$ 107,549
Western Gas Partners, LP [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly distribution per unit	$ 0.965	[2]	$ 0.950	$ 0.935	$ 0.920	$ 0.905	$ 0.890	$ 0.875
Total quarterly cash distribution	$ 230,239	[2]	$ 225,691	$ 221,133	$ 216,586	$ 212,038	$ 207,491	$ 188,753
[1]	The Board of Directors declared a cash distribution to WGP unitholders for the third quarter of 2018 of $0.59500 per unit, or $130.3 million in aggregate. The cash distribution is payable on November 21, 2018, to WGP unitholders of record at the close of business on October 31, 2018.
[2]	The Board of Directors of WES GP declared a cash distribution to WES unitholders for the third quarter of 2018 of $0.965 per unit, or $230.2 million in aggregate, including incentive distributions, but excluding distributions on WES Class C units (see WES Class C unit distributions below). The cash distribution is payable on November 13, 2018, to WES unitholders of record at the close of business on October 31, 2018.

Partnership Distributions - Add

Partnership Distributions - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	May 02, 2017	Mar. 01, 2017	Mar. 31, 2017	Jun. 30, 2017	Sep. 30, 2018
Distribution Made to Limited Partner [Line Items]
Partnership agreement day requirement of distribution of available cash					55 days
Western Gas Partners, LP [Member]
Distribution Made to Limited Partner [Line Items]
Partnership agreement day requirement of distribution of available cash					45 days
Incentive distributions percentage					48.00%
Western Gas Partners, LP [Member] | Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Distribution sharing percentage					1.50%
Western Gas Partners, LP [Member] | Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Distribution sharing percentage					49.50%
Western Gas Partners, LP [Member] | Class C Units [Member]
Distribution Made to Limited Partner [Line Items]
Class C units, discount rate percentage on distribution					6.00%
Western Gas Partners, LP [Member] | Series A Preferred Units [Member]
Distribution Made to Limited Partner [Line Items]
Series A Preferred units, quarterly distribution per unit				$ 0.68
Series A Preferred units, quarterly cash distribution			$ 7.5
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Series A Preferred Units March 2017 Conversion [Member]
Distribution Made to Limited Partner [Line Items]
Series A Preferred units, percentage converted		50.00%
Series A Preferred units, common units issued upon conversion		1
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Series A Preferred Units May 2017 Conversion [Member]
Distribution Made to Limited Partner [Line Items]
Series A Preferred units, percentage converted	50.00%
Series A Preferred units, common units issued upon conversion	1

Equity and Partners' Capital -

Equity and Partners' Capital - Partnership Interests Table (Details) - Western Gas Partners, LP [Member]	9 Months Ended
	Sep. 30, 2018shares
Change In Units [Roll Forward]
Balance	168,429,056
Units issued	801,546
Long-Term Incentive Plan award vestings	7,180
Balance	169,237,782
Common Units [Member]
Change In Units [Roll Forward]
Balance	152,602,105
Long-Term Incentive Plan award vestings	7,180
Balance	152,609,285
Class C Units [Member]
Change In Units [Roll Forward]
Balance	13,243,883
Units issued	801,546
Balance	14,045,429
General Partner [Member]
Change In Units [Roll Forward]
Balance	2,583,068
Balance	2,583,068

Equity and Partners' Capital _2

Equity and Partners' Capital - Additional Information (Details) $ in Millions	Jun. 07, 2018shares	May 02, 2017shares	Mar. 01, 2017shares	Jun. 30, 2015$ / unitshares	Nov. 30, 2014shares	Sep. 30, 2018shares	Dec. 31, 2016shares	Dec. 31, 2017shares	Jul. 31, 2017USD ($)
Schedule of Investments [Line Items]
Limited partner units owned						218,937,797		218,933,141
7.50% Tangible Equity Units [Member] | Anadarko [Member]
Schedule of Investments [Line Items]
Tangible equity units, number issued				9,200,000
Tangible equity units, rate				7.50%
Tangible equity units, stated amount per unit | $ / unit				50
Debt instrument, maturity date				Jun. 7, 2018
Tangible equity units, number settled	9,200,000
7.50% Tangible Equity Units [Member] | Anadarko [Member] | Over-Allotment Option [Member]
Schedule of Investments [Line Items]
Tangible equity units, number issued				1,200,000
7.50% Tangible Equity Units [Member] | Common Units [Member] | Anadarko [Member]
Schedule of Investments [Line Items]
Units issued	8,207,204
Western Gas Equity Partners, LP [Member] | Public [Member]
Schedule of Investments [Line Items]
Limited partner units owned						48,557,636
Ownership interest						22.20%
Western Gas Partners, LP [Member] | Public [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned						100,465,859
Ownership interest						59.40%
Anadarko [Member] | Western Gas Equity Partners, LP [Member]
Schedule of Investments [Line Items]
Limited partner units owned						170,380,161
Ownership interest						77.80%
Western Gas Equity Partners, LP [Member] | Western Gas Partners, LP [Member]
Schedule of Investments [Line Items]
General partner units owned						2,583,068
General partner's interest						1.50%
Western Gas Equity Partners, LP [Member] | Western Gas Partners, LP [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned						50,132,046
Ownership interest						29.60%
Western Gas Equity Partners, LP [Member] | Western Gas Partners, LP [Member] | Incentive Distribution Rights [Member]
Schedule of Investments [Line Items]
General partner's interest						100.00%
Western Gas Partners, LP [Member]
Schedule of Investments [Line Items]
Units issued						801,546
Western Gas Partners, LP [Member] | July 2017 COP [Member]
Schedule of Investments [Line Items]
Maximum aggregate principal of common units | $									$ 500
Western Gas Partners, LP [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Units issued						801,546
Class C units, common units issued upon conversion						1
Western Gas Partners, LP [Member] | Class C Units [Member] | Other Subsidiaries of Anadarko [Member]
Schedule of Investments [Line Items]
Units issued					10,913,853
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Series A Preferred Units March 2017 Conversion [Member]
Schedule of Investments [Line Items]
Series A Preferred units, percentage converted			50.00%
Series A Preferred units, common units issued upon conversion			1
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Series A Preferred Units May 2017 Conversion [Member]
Schedule of Investments [Line Items]
Series A Preferred units, percentage converted		50.00%
Series A Preferred units, common units issued upon conversion		1
Western Gas Partners, LP [Member] | Series A Preferred Units [Member] | Private Investor [Member]
Schedule of Investments [Line Items]
Units issued							21,922,831
Other Subsidiaries of Anadarko [Member] | Western Gas Partners, LP [Member] | Common Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned						2,011,380
Other Subsidiaries of Anadarko [Member] | Western Gas Partners, LP [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Limited partner units owned						14,045,429
Other Subsidiaries of Anadarko [Member] | Western Gas Partners, LP [Member] | Common and Class C Units [Member]
Schedule of Investments [Line Items]
Ownership interest						9.50%

Transactions with Affiliates -

Transactions with Affiliates - Commodity Price Swap Agreements Tables (Details) - Western Gas Partners, LP [Member]		Sep. 30, 2018$ / bbl$ / MMBTU	Dec. 20, 2017$ / bbl$ / MMBTU	Dec. 01, 2016$ / bbl$ / MMBTU
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Ethane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		18.41
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Propane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		47.08
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Isobutane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		62.09
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Normal Butane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		54.62
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Natural Gasoline [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		72.88
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Condensate [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		76.47
DJ Basin Complex [Member] | Years 2017 - 2018 [Member] | Natural Gas (per MMBtu) [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price | $ / MMBTU		5.96
DJ Basin Complex [Member] | Year 2017 [Member] | Ethane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			5.09
DJ Basin Complex [Member] | Year 2017 [Member] | Propane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			18.85
DJ Basin Complex [Member] | Year 2017 [Member] | Isobutane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			26.83
DJ Basin Complex [Member] | Year 2017 [Member] | Normal Butane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			26.20
DJ Basin Complex [Member] | Year 2017 [Member] | Natural Gasoline [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			41.84
DJ Basin Complex [Member] | Year 2017 [Member] | Condensate [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			45.40
DJ Basin Complex [Member] | Year 2017 [Member] | Natural Gas (per MMBtu) [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price | $ / MMBTU	[1]			3.05
DJ Basin Complex [Member] | Year 2018 [Member] | Ethane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		5.41
DJ Basin Complex [Member] | Year 2018 [Member] | Propane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		28.72
DJ Basin Complex [Member] | Year 2018 [Member] | Isobutane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		32.92
DJ Basin Complex [Member] | Year 2018 [Member] | Normal Butane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		32.71
DJ Basin Complex [Member] | Year 2018 [Member] | Natural Gasoline [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		48.04
DJ Basin Complex [Member] | Year 2018 [Member] | Condensate [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		49.36
DJ Basin Complex [Member] | Year 2018 [Member] | Natural Gas (per MMBtu) [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price | $ / MMBTU	[1]		2.21
MGR Assets [Member] | Years 2017 - 2018 [Member] | Ethane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		23.11
MGR Assets [Member] | Years 2017 - 2018 [Member] | Propane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		52.90
MGR Assets [Member] | Years 2017 - 2018 [Member] | Isobutane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		73.89
MGR Assets [Member] | Years 2017 - 2018 [Member] | Normal Butane [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		64.93
MGR Assets [Member] | Years 2017 - 2018 [Member] | Natural Gasoline [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		81.68
MGR Assets [Member] | Years 2017 - 2018 [Member] | Condensate [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price		81.68
MGR Assets [Member] | Years 2017 - 2018 [Member] | Natural Gas (per MMBtu) [Member]
Commodity Price Risk Swap [Line Items]
Commodity swap fixed price | $ / MMBTU		4.87
MGR Assets [Member] | Year 2017 [Member] | Ethane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			4.08
MGR Assets [Member] | Year 2017 [Member] | Propane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			19.24
MGR Assets [Member] | Year 2017 [Member] | Isobutane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			25.79
MGR Assets [Member] | Year 2017 [Member] | Normal Butane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			25.16
MGR Assets [Member] | Year 2017 [Member] | Natural Gasoline [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			45.01
MGR Assets [Member] | Year 2017 [Member] | Condensate [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]			53.55
MGR Assets [Member] | Year 2017 [Member] | Natural Gas (per MMBtu) [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price | $ / MMBTU	[1]			3.05
MGR Assets [Member] | Year 2018 [Member] | Ethane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		2.52
MGR Assets [Member] | Year 2018 [Member] | Propane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		25.83
MGR Assets [Member] | Year 2018 [Member] | Isobutane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		30.03
MGR Assets [Member] | Year 2018 [Member] | Normal Butane [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		29.82
MGR Assets [Member] | Year 2018 [Member] | Natural Gasoline [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		47.25
MGR Assets [Member] | Year 2018 [Member] | Condensate [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price	[1]		56.76
MGR Assets [Member] | Year 2018 [Member] | Natural Gas (per MMBtu) [Member]
Commodity Price Risk Swap [Line Items]
Commodity market price | $ / MMBTU	[1]		2.21
[1]	Represents the New York Mercantile Exchange forward strip price as of December 1, 2016, and December 20, 2017, for the 2017 Market Prices and 2018 Market Prices, respectively, adjusted for product specification, location, basis and, in the case of NGLs, transportation and fractionation costs.

Transactions with Affiliates _2

Transactions with Affiliates - Purchases Table (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Related Party Transaction [Line Items]
Partners’ capital adjustment	$ 0	$ (1,373)
Western Gas Partners, LP [Member] | Affiliates [Member]
Related Party Transaction [Line Items]
Cash consideration	254	3,910
Net carrying value	(254)	(5,283)
Partners’ capital adjustment	$ 0	$ (1,373)

Transactions with Affiliates _3

Transactions with Affiliates - Summary of Affiliate Transactions Table (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Related Party Transaction [Line Items]
Revenues and other		$ 507,762	$ 574,695	$ 1,432,483		$ 1,616,338
Equity income, net – affiliates	[1]	43,110	21,519	102,752		62,708
Cost of product	[2]	105,966	239,223	303,518		631,859
Operation and maintenance	[2]	111,359	79,536	300,266		229,444
General and administrative	[2]	15,158	12,922	44,853		37,595
Operating expenses		351,307	417,594	1,074,622		1,320,682
Interest income	[3]	4,225	4,225	12,675		12,675
Interest expense		48,316	36,117	133,359		108,447
Distributions to unitholders	[4]			372,189		324,290
Above-market component of swap agreements with Anadarko		12,601	18,049	40,722	[4]	46,719	[4]
Affiliates [Member]
Related Party Transaction [Line Items]
Revenues and other	[1]	274,514	351,127	766,179		982,595
Cost of product	[1]	46,971	22,902	131,428		60,497
Operation and maintenance	[5]	25,145	18,110	68,830		53,661
General and administrative	[6]	11,780	10,414	35,000		29,637
Operating expenses		83,896	51,426	235,258		143,795
Interest expense	[7]	0	0	0		71
Settlement of the Deferred purchase price obligation - Anadarko	[8]			0		(37,346)
Distributions to unitholders	[9]	99,247	94,205	298,818		264,533
Affiliates [Member] | Western Gas Partners, LP [Member]
Related Party Transaction [Line Items]
Distributions to unitholders	[10]	1,911	1,790	5,642		5,280
Affiliates [Member] | Deferred Purchase Price Obligation - Anadarko [Member]
Related Party Transaction [Line Items]
Settlement of the Deferred purchase price obligation - Anadarko	[11]	$ 0	$ 0	$ 0		$ (37,346)
[1]	Represents amounts earned or incurred on and subsequent to the date of the 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.
[2]	Cost of product includes product purchases from affiliates (as defined in Note 1) of $47.0 million and $131.4 million for the three and nine months ended September 30, 2018, respectively, and $22.9 million and $60.5 million for the three and nine months ended September 30, 2017, respectively. Operation and maintenance includes charges from affiliates of $25.1 million and $68.8 million for the three and nine months ended September 30, 2018, respectively, and $18.1 million and $53.7 million for the three and nine months ended September 30, 2017, respectively. General and administrative includes charges from affiliates of $11.8 million and $35.0 million for the three and nine months ended September 30, 2018, respectively, and $10.4 million and $29.6 million for the three and nine months ended September 30, 2017, respectively. See Note 6.
[3]	Represents interest income recognized on the note receivable from Anadarko.
[4]	See Note 6.
[5]	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.
[6]	Represents general and administrative expense incurred on and subsequent to the date of the 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 Anadarko Incentive Plan within this Note 6) and amounts charged by Anadarko under the WGP and WES omnibus agreements.
[7]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).
[8]	See Note 3.
[9]	Represents distributions paid under WGP’s partnership agreement (see Note 4 and Note 5).
[10]	Represents distributions paid to other subsidiaries of Anadarko under WES’s partnership agreement (see Note 4 and Note 5).
[11]	Represents the cash payment to Anadarko for the settlement of the Deferred purchase price obligation - Anadarko (see Note 3).

Transactions with Affiliates _4

Transactions with Affiliates - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended
		May 31, 2008	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Note receivable - Anadarko			$ 260,000,000		$ 260,000,000		$ 260,000,000
Above-market component of swap agreements with Anadarko	[1]				40,722,000
Contributions of equity-based compensation to WES by Anadarko					$ 4,306,000
Western Gas Equity Partners Long Term Incentive Plan [Member]
Related Party Transaction [Line Items]
Units vesting period					3 years
Equity-based compensation expense			62,000	$ 63,000	$ 200,000	$ 200,000
Commodity Price Swap Agreement [Member]
Related Party Transaction [Line Items]
Net gains (losses) on commodity price swap agreements			(3,737,000)		(6,351,000)
Affiliates [Member] | Commodity Price Swap Agreement [Member]
Related Party Transaction [Line Items]
Net gains (losses) on commodity price swap agreements			(3,737,000)	(1,000,000)	$ (6,351,000)	(600,000)
Independent Director [Member] | Western Gas Equity Partners Long Term Incentive Plan [Member]
Related Party Transaction [Line Items]
Units vesting period					1 year
Western Gas Partners, LP [Member] | Anadarko Incentive Plan [Member]
Related Party Transaction [Line Items]
Equity-based compensation expense			1,400,000	1,200,000	$ 5,200,000	3,200,000
Contributions of equity-based compensation to WES by Anadarko					$ 4,300,000
Western Gas Partners, LP [Member] | Western Gas Partners Long Term Incentive Plan [Member]
Related Party Transaction [Line Items]
Units vesting period					3 years
Equity-based compensation expense			$ 100,000	$ 100,000	$ 300,000	$ 300,000
Western Gas Partners, LP [Member] | Natural Gas [Member] | Gathering, Treating, Transportation and Disposal [Member]
Related Party Transaction [Line Items]
Affiliate throughput percent			41.00%	33.00%	37.00%	34.00%
Western Gas Partners, LP [Member] | Natural Gas [Member] | Processing [Member]
Related Party Transaction [Line Items]
Affiliate throughput percent			35.00%	39.00%	35.00%	42.00%
Western Gas Partners, LP [Member] | Crude Oil, NGL and Produced Water [Member] | Gathering, Treating, Transportation and Disposal [Member]
Related Party Transaction [Line Items]
Affiliate throughput percent			77.00%	54.00%	71.00%	50.00%
Western Gas Partners, LP [Member] | Affiliates [Member]
Related Party Transaction [Line Items]
Note receivable - Anadarko		$ 260,000,000	$ 260,000,000		$ 260,000,000
Note receivable, due date		May 14, 2038
Fixed annual rate for note receivable bearing interest		6.50%
Western Gas Partners, LP [Member] | Affiliates [Member] | Level 2 Inputs [Member] | Valuation, Market Approach [Member]
Related Party Transaction [Line Items]
Fair value of the note receivable			$ 300,900,000		$ 300,900,000		$ 325,200,000
Western Gas Partners, LP [Member] | Independent Director [Member] | Western Gas Partners Long Term Incentive Plan [Member]
Related Party Transaction [Line Items]
Units vesting period					1 year
[1]	See Note 6.

Property, Plant and Equipment -

Property, Plant and Equipment - Historical Cost Table (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 8,912,755	$ 7,864,535
Less accumulated depreciation	2,494,121	2,133,644
Net property, plant and equipment	6,418,634	5,730,891
Western Gas Partners, LP [Member] | Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	4,653	4,450
Western Gas Partners, LP [Member] | Gathering Systems and Processing Complexes [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 7,883,265	7,113,114
Western Gas Partners, LP [Member] | Gathering Systems and Processing Complexes [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Western Gas Partners, LP [Member] | Gathering Systems and Processing Complexes [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	47 years
Western Gas Partners, LP [Member] | Pipelines and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 137,769	137,644
Western Gas Partners, LP [Member] | Pipelines and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Western Gas Partners, LP [Member] | Pipelines and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Western Gas Partners, LP [Member] | Assets Under Construction [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 856,092	579,501
Western Gas Partners, LP [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 30,976	$ 29,826
Western Gas Partners, LP [Member] | Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Western Gas Partners, LP [Member] | Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Impairments	$ 25,317,000	$ 2,159,000	$ 152,708,000	$ 170,079,000	$ 178,400,000
Western Gas Partners, LP [Member] | Fort Union [Member]
Property, Plant and Equipment [Line Items]
Equity investment impairment loss					3,100,000
Western Gas Partners, LP [Member] | Third Creek Gathering System [Member]
Property, Plant and Equipment [Line Items]
Impairments			125,900,000
Western Gas Partners, LP [Member] | Third Creek Gathering System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value	1,800,000		1,800,000
Western Gas Partners, LP [Member] | Kitty Draw Gathering System [Member]
Property, Plant and Equipment [Line Items]
Impairments			8,100,000
Western Gas Partners, LP [Member] | Kitty Draw Gathering System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value	0		0
Western Gas Partners, LP [Member] | Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments			18,700,000		19,600,000
Western Gas Partners, LP [Member] | GNB NGL Pipeline [Member]
Property, Plant and Equipment [Line Items]
Impairments			10,900,000
Western Gas Partners, LP [Member] | GNB NGL Pipeline [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value	10,000,000		10,000,000
Western Gas Partners, LP [Member] | Chipeta Complex [Member]
Property, Plant and Equipment [Line Items]
Impairments			5,600,000
Western Gas Partners, LP [Member] | Chipeta Complex [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value	$ 1,500,000		$ 1,500,000
Western Gas Partners, LP [Member] | Granger Complex [Member]
Property, Plant and Equipment [Line Items]
Impairments					158,800,000
Western Gas Partners, LP [Member] | Granger Complex [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value					48,500,000
Western Gas Partners, LP [Member] | Hilight System [Member]
Property, Plant and Equipment [Line Items]
Impairments					8,200,000
Western Gas Partners, LP [Member] | Granger Straddle Plant [Member]
Property, Plant and Equipment [Line Items]
Impairments					3,700,000
Western Gas Partners, LP [Member] | Granger Straddle Plant [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value					600,000
Western Gas Partners, LP [Member] | Northeast Wyoming Facility [Member]
Property, Plant and Equipment [Line Items]
Impairments					2,000,000
Western Gas Partners, LP [Member] | Northeast Wyoming Facility [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value					$ 400,000

Equity Investments - Equity Inv

Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Balance				$ 566,211
Acquisitions				161,858
Investment earnings (loss), net of amortization	[1]	$ 43,110	$ 21,519	102,752		$ 62,708
Contributions				67,463
Capitalized interest				516
Distributions				(93,827)		(64,313)
Distributions in excess of cumulative earnings				(18,097)	[2]	$ (16,255)
Balance		786,876		786,876
Western Gas Partners, LP [Member] | Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance				7,030
Acquisitions				0
Investment earnings (loss), net of amortization				(892)
Contributions				0
Capitalized interest				0
Distributions				(194)
Distributions in excess of cumulative earnings	[2]			(2,889)
Balance		3,055		3,055
Western Gas Partners, LP [Member] | White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance				44,945
Acquisitions				0
Investment earnings (loss), net of amortization				8,547
Contributions				1,278
Capitalized interest				0
Distributions				(8,111)
Distributions in excess of cumulative earnings	[2]			(3,109)
Balance		43,550		43,550
Western Gas Partners, LP [Member] | Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance				42,528
Acquisitions				0
Investment earnings (loss), net of amortization				635
Contributions				0
Capitalized interest				0
Distributions				(2,091)
Distributions in excess of cumulative earnings	[2]			(2,015)
Balance		39,057		39,057
Western Gas Partners, LP [Member] | Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance				110,299
Acquisitions				0
Investment earnings (loss), net of amortization				22,916
Contributions				0
Capitalized interest				0
Distributions				(22,945)
Distributions in excess of cumulative earnings	[2]			(3,305)
Balance		106,965		106,965
Western Gas Partners, LP [Member] | TEFR Interests [Member]
Schedule of Equity Method Investments [Line Items]
Balance				361,409
Acquisitions				0
Investment earnings (loss), net of amortization				47,736
Contributions				24,680
Capitalized interest				0
Distributions				(43,989)
Distributions in excess of cumulative earnings	[2]			(6,779)
Balance		383,057		383,057
Western Gas Partners, LP [Member] | Whitethorn [Member]
Schedule of Equity Method Investments [Line Items]
Balance				0
Acquisitions				150,563
Investment earnings (loss), net of amortization				23,810
Contributions				7,069
Capitalized interest				0
Distributions				(16,497)
Distributions in excess of cumulative earnings	[2]			0
Balance		164,945		164,945
Western Gas Partners, LP [Member] | Cactus II [Member]
Schedule of Equity Method Investments [Line Items]
Balance				0
Acquisitions				11,295
Investment earnings (loss), net of amortization				0
Contributions				34,436
Capitalized interest				516
Distributions				0
Distributions in excess of cumulative earnings	[2]			0
Balance		$ 46,247		$ 46,247
[1]	Represents amounts earned or incurred on and subsequent to the date of the 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.
[2]	Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, are calculated on an individual investment basis.

Components of Working Capital -

Components of Working Capital - Accounts Receivable, Net Table (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables, net		$ 224,719	$ 160,194
Other receivables, net		168	45
Total accounts receivable, net	[1]	$ 224,887	$ 160,239
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $59.1 million and $36.1 million as of September 30, 2018, and December 31, 2017, respectively.

Components of Working Capital_2

Components of Working Capital - Other Current Assets Table (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Other Current Assets [Line Items]
Natural gas liquids inventory		$ 11,212	$ 10,788
Imbalance receivables		3,829	1,640
Prepaid insurance		3,203	2,955
Contract assets		2,748	0
Other		5,127	0
Total other current assets	[1]	$ 26,119	$ 15,383
[1]	Other current assets includes affiliate amounts of $1.4 million and zero as of September 30, 2018, and December 31, 2017, respectively.

Components of Working Capital_3

Components of Working Capital - Accrued Liabilities Table (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Components Of Working Capital [Abstract]
Accrued interest expense		$ 54,556	$ 40,646
Short-term asset retirement obligations	[1]	42,872	2,304
Short-term remediation and reclamation obligations		833	833
Income taxes payable		247	2,495
Contract liabilities		8,031	0
Other		7,965	1,714
Total accrued liabilities	[2]	114,504	$ 47,992
Liabilities incurred		$ 40,200
[1]	As of September 30, 2018, includes $40.2 million of short-term liabilities incurred during the second quarter of 2018 related to the shutdowns at the Third Creek and Kitty Draw gathering systems. See Note 1 for further information.
[2]	Accrued liabilities includes affiliate amounts of $2.3 million and $0.2 million as of September 30, 2018, and December 31, 2017, respectively.

Debt and Interest Expense - Deb

Debt and Interest Expense - Debt Outstanding Table (Details) - USD ($)		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Short-term debt, carrying value		$ 28,000,000	$ 0
Total long-term debt, principal		4,620,000,000	3,518,000,000
Long-term debt, carrying value		4,566,464,000	3,492,712,000
Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	4,475,935,000	3,622,177,000
WGP RCF [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal		28,000,000	28,000,000
Short-term debt, carrying value		28,000,000
Long-term debt, carrying value			28,000,000
WGP RCF [Member] | Revolving Credit Facility [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Short-term debt, fair value	[1]	28,000,000
Long-term debt, fair value	[1]		28,000,000
Western Gas Partners, LP [Member] | WES RCF [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal		0	370,000,000
Long-term debt, carrying value		0	370,000,000
Western Gas Partners, LP [Member] | WES RCF [Member] | Revolving Credit Facility [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 0	370,000,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		2.60%
Debt instrument, maturity date		Aug. 15, 2018
Principal		$ 0	350,000,000
Long-term debt, carrying value		0	349,684,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 0	350,631,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.375%
Debt instrument, maturity date		Jun. 1, 2021
Principal		$ 500,000,000	500,000,000
Long-term debt, carrying value		496,669,000	495,815,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 517,160,000	530,647,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.00%
Debt instrument, maturity date		Jul. 1, 2022
Principal		$ 670,000,000	670,000,000
Long-term debt, carrying value		669,020,000	668,849,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 668,198,000	684,043,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		3.95%
Debt instrument, maturity date		Jun. 1, 2025
Principal		$ 500,000,000	500,000,000
Long-term debt, carrying value		492,596,000	491,885,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 478,470,000	500,885,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.65%
Debt instrument, maturity date		Jul. 1, 2026
Principal		$ 500,000,000	500,000,000
Long-term debt, carrying value		495,592,000	495,245,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 492,502,000	520,144,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.50%
Debt instrument, maturity date		Mar. 1, 2028
Principal		$ 400,000,000	0
Long-term debt, carrying value		394,514,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 384,964,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.750% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.75%
Debt instrument, maturity date		Aug. 15, 2028
Principal		$ 400,000,000	0
Long-term debt, carrying value		395,806,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.750% Senior Notes due 2028 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 391,532,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.45%
Debt instrument, maturity date		Apr. 1, 2044
Principal		$ 600,000,000	600,000,000
Long-term debt, carrying value		593,319,000	593,234,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 565,485,000	637,827,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.30%
Debt instrument, maturity date		Mar. 1, 2048
Principal		$ 700,000,000	0
Long-term debt, carrying value		686,601,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 645,643,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.500% Senior Notes due 2048 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.50%
Debt instrument, maturity date		Aug. 15, 2048
Principal		$ 350,000,000	0
Long-term debt, carrying value		342,347,000	0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.500% Senior Notes due 2048 [Member] | Valuation, Market Approach [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 331,981,000	$ 0
[1]	Fair value is measured using the market approach and Level 2 inputs.

Debt and Interest Expense - D_2

Debt and Interest Expense - Debt Activity Table (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Changes in Debt Outstanding [Roll Forward]
Beginning balance	$ 3,492,712
Other	(28,248)
Ending balance	4,594,464
Western Gas Partners, LP [Member] | WES RCF [Member] | Revolving Credit Facility [Member]
Changes in Debt Outstanding [Roll Forward]
RCF borrowings	320,000
Repayments of RCF borrowings	(690,000)
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes	400,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes	700,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.750% Senior Notes due 2028 [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes	400,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.500% Senior Notes due 2048 [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes	350,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member]
Changes in Debt Outstanding [Roll Forward]
Repayment of senior notes	$ (350,000)

Debt and Interest Expense - Int

Debt and Interest Expense - Interest Expense Table (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Interest expense		$ (48,316)	$ (36,117)	$ (133,359)	$ (108,447)
Third Parties [Member]
Debt Instrument [Line Items]
Long-term and short-term debt		(53,229)	(36,223)	(143,436)	(106,412)
Amortization of debt issuance costs and commitment fees		(2,054)	(2,009)	(6,955)	(5,955)
Capitalized interest		6,967	2,115	17,032	3,991
Interest expense		(48,316)	(36,117)	(133,359)	(108,376)
Affiliates [Member]
Debt Instrument [Line Items]
Interest expense	[1]	0	0	0	(71)
Affiliates [Member] | Deferred Purchase Price Obligation - Anadarko [Member]
Debt Instrument [Line Items]
Deferred purchase price obligation - Anadarko	[2]	$ 0	$ 0	$ 0	$ (71)
[1]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).
[2]	See Note 3 for a discussion of the Deferred purchase price obligation - Anadarko.

Debt and Interest Expense - Add

Debt and Interest Expense - Additional Information (Details) - USD ($)	Feb. 16, 2018	Sep. 30, 2018	Sep. 30, 2017	Aug. 31, 2018	Mar. 31, 2018	Feb. 25, 2014
Revolving Credit Facility [Member] | WGP RCF [Member]
Debt Instrument [Line Items]
Facility, maximum borrowing capacity	$ 35,000,000
Facility, expiration date	Mar. 14, 2019
Facility, outstanding borrowings		$ 28,000,000
Facility, available borrowing capacity		$ 7,000,000
Facility, interest rate at period end		4.25%	3.24%
Facility, fee rate		0.30%	0.30%
Western Gas Partners, LP [Member] | 4.750% Senior Notes due 2028 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.75%
Offering percent				99.818%
Effective interest rate				4.885%
Western Gas Partners, LP [Member] | 5.500% Senior Notes due 2048 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.50%
Offering percent				98.912%
Effective interest rate				5.652%
Western Gas Partners, LP [Member] | 4.500% Senior Notes due 2028 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.50%
Offering percent					99.435%
Effective interest rate					4.682%
Western Gas Partners, LP [Member] | 5.300% Senior Notes due 2048 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.30%
Offering percent					99.169%
Effective interest rate					5.431%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member]
Debt Instrument [Line Items]
Facility, maximum borrowing capacity	$ 1,500,000,000					$ 1,200,000,000
Facility, expiration date	Feb. 15, 2023
Facility, outstanding borrowings		$ 0
Facility, available borrowing capacity		$ 1,495,400,000
Facility, interest rate at period end		3.56%	2.54%
Facility, fee rate		0.20%	0.20%
Facility, expandable maximum borrowing capacity	$ 2,000,000,000
Outstanding letters of credit		$ 4,600,000
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | Minimum [Member]
Debt Instrument [Line Items]
Facility, fee rate		0.125%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | Maximum [Member]
Debt Instrument [Line Items]
Facility, fee rate		0.25%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | London Interbank Offered Rate (LIBOR) [Member] | Alternate Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin added		1.00%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable margin added		1.00%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable margin added		1.50%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | Percentage Above Federal Funds Effective Rate [Member] | Alternate Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin added		0.50%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | Base Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable margin added		0.00%
Western Gas Partners, LP [Member] | Revolving Credit Facility [Member] | WES RCF [Member] | Base Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable margin added		0.50%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 17, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Contract liabilities		$ 8,031		$ 8,031			$ 0
Revenues and other		507,762	$ 574,695	1,432,483	$ 1,616,338
Western Gas Partners, LP [Member]
Loss Contingencies [Line Items]
Rent expense associated with office and equipment leases		14,600	$ 12,000	40,500	$ 32,700
Western Gas Partners, LP [Member] | DBJV Arbitration [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Contract liabilities						$ 7,500
Western Gas Partners, LP [Member] | Delaware Basin JV Gathering LLC [Member] | DBJV Arbitration [Member]
Loss Contingencies [Line Items]
Percentage ownership interest	50.00%
Percentage third-party ownership interest	50.00%
Service Revenues - Fee Based [Member]
Loss Contingencies [Line Items]
Revenues and other		409,106		$ 1,146,099
Service Revenues - Fee Based [Member] | Western Gas Partners, LP [Member] | DBJV Arbitration [Member] | Settled Litigation [Member]
Loss Contingencies [Line Items]
Revenues and other		$ 7,500