Western Midstream Partners 10-Q 2 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document And Entity Information [Abstract]
Trading Symbol	WES
Entity Registrant Name	Western Gas Partners LP
Entity Central Index Key	1,414,475
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Units Outstanding		152,602,105

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Revenues and Other
Product sales		$ 75,937
Total revenues and other		437,168	$ 516,193
Equity income, net – affiliates	[1]	20,424	19,461
Operating expenses
Cost of product	[2]	77,799	189,359
Operation and maintenance	[2]	88,279	73,760
General and administrative	[2]	14,132	12,659
Property and other taxes		12,382	12,294
Depreciation and amortization		76,842	69,702
Impairments		148	164,742
Total operating expenses		269,582	522,516
Gain (loss) on divestiture and other, net	[3],[4]	116	119,487
Proceeds from business interruption insurance claims		0	5,767
Operating income (loss)		188,126	138,392
Interest income - affiliates	[5]	4,225	4,225
Interest expense	[6]	(39,283)	(35,504)
Other income (expense), net		782	430
Income (loss) before income taxes		153,850	107,543
Income tax (benefit) expense		1,502	3,552
Net income (loss)		152,348	103,991
Net income attributable to noncontrolling interest		2,985	2,102
Net income (loss) attributable to Western Gas Partners, LP		149,363	101,889
Limited partners' interest in net income (loss):
General partner interest in net (income) loss	[7]	(83,439)	(68,162)
Series A Preferred Units [Member]
Limited partners' interest in net income (loss):
Limited partners’ interest in net income (loss)	[8]	0	(28,174)
Common and Class C Units [Member]
Limited partners' interest in net income (loss):
Limited partners’ interest in net income (loss)	[7]	(65,924)	(5,553)
Common Units [Member]
Limited partners' interest in net income (loss):
Limited partners’ interest in net income (loss)	[8]	$ (58,323)	$ (1,714)
Net income (loss) per common unit – basic and diluted	[9]	$ 0.38	$ 0.01
Fee Based [Member]
Revenues and Other
Service revenues - fee and product based		$ 338,419
Product Based [Member]
Revenues and Other
Service revenues - fee and product based		22,593
Affiliates [Member]
Revenues and Other
Product sales		54,819	$ 142,841
Total revenues and other	[1]	241,062	315,155
Operating expenses
Cost of product	[1]	20,244	15,988
Operation and maintenance	[10]	20,248	17,089
General and administrative	[11]	11,614	9,535
Total operating expenses		52,106	42,612
Interest expense	[12]	0	(71)
Affiliates [Member] | Fee Based [Member]
Revenues and Other
Service revenues - fee and product based		186,001	172,314
Affiliates [Member] | Product Based [Member]
Revenues and Other
Service revenues - fee and product based		242	0
Third Parties [Member]
Revenues and Other
Product sales		21,118	63,684
Other		219	1,854
Total revenues and other		196,106	201,038
Operating expenses
Interest expense		(39,283)	(35,433)
Third Parties [Member] | Fee Based [Member]
Revenues and Other
Service revenues - fee and product based		152,418	135,500
Third Parties [Member] | Product Based [Member]
Revenues and Other
Service revenues - fee and product based		$ 22,351	$ 0
[1]	Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, recognized under gathering, treating or processing agreements, and purchase and sale agreements.
[2]	Cost of product includes product purchases from Anadarko (as defined in Note 1) of $20.2 million and $16.0 million for the three months ended March 31, 2018 and 2017, respectively. Operation and maintenance includes charges from Anadarko of $20.2 million and $17.1 million for the three months ended March 31, 2018 and 2017, respectively. General and administrative includes charges from Anadarko of $11.6 million and $9.5 million for the three months ended March 31, 2018 and 2017, respectively. See Note 6.
[3]	Includes losses related to an incident at the DBM complex for the three months ended March 31, 2017. See Note 1.
[4]	Includes losses related to an incident at the DBM complex for the three months ended March 31, 2017. See Note 1.
[5]	Represents interest income recognized on the note receivable from Anadarko.
[6]	Includes affiliate (as defined in Note 1) amounts of zero and $(0.1) million for the three months ended March 31, 2018 and 2017, respectively. See Note 10.
[7]	Represents net income (loss) earned on and subsequent to the date of acquisition of the Partnership assets (as defined in Note 1). See Note 5.
[8]	Adjusted to reflect amortization of the beneficial conversion features.
[9]	See Note 5 for the calculation of net income (loss) per common unit.
[10]	Represents expenses incurred on and subsequent to the date of the acquisition of Partnership assets, as well as expenses incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets.
[11]	Represents general and administrative expense incurred on and subsequent to the date of the acquisition of Partnership assets, as well as a management services fee for reimbursement of expenses incurred by Anadarko for periods prior to the acquisition of the Partnership assets by the Partnership. These amounts include equity-based compensation expense allocated to the Partnership by Anadarko (see WES LTIP and Anadarko Incentive Plan within this Note 6).
[12]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).

Consolidated Statements of Ope3

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Cost of product	[1]	$ 77,799	$ 189,359
Operation and maintenance	[1]	88,279	73,760
General and administrative	[1]	14,132	12,659
Interest expense	[2]	(39,283)	(35,504)
Affiliates [Member]
Cost of product	[3]	20,244	15,988
Operation and maintenance	[4]	20,248	17,089
General and administrative	[5]	11,614	9,535
Interest expense	[6]	$ 0	$ (71)
[1]	Cost of product includes product purchases from Anadarko (as defined in Note 1) of $20.2 million and $16.0 million for the three months ended March 31, 2018 and 2017, respectively. Operation and maintenance includes charges from Anadarko of $20.2 million and $17.1 million for the three months ended March 31, 2018 and 2017, respectively. General and administrative includes charges from Anadarko of $11.6 million and $9.5 million for the three months ended March 31, 2018 and 2017, respectively. See Note 6.
[2]	Includes affiliate (as defined in Note 1) amounts of zero and $(0.1) million for the three months ended March 31, 2018 and 2017, respectively. See Note 10.
[3]	Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, recognized under gathering, treating or processing agreements, and purchase and sale agreements.
[4]	Represents expenses incurred on and subsequent to the date of the acquisition of Partnership assets, as well as expenses incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets.
[5]	Represents general and administrative expense incurred on and subsequent to the date of the acquisition of Partnership assets, as well as a management services fee for reimbursement of expenses incurred by Anadarko for periods prior to the acquisition of the Partnership assets by the Partnership. These amounts include equity-based compensation expense allocated to the Partnership by Anadarko (see WES LTIP and Anadarko Incentive Plan within this Note 6).
[6]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents		$ 521,426	$ 78,814
Accounts receivable, net	[1]	189,074	160,432
Other current assets	[2]	22,747	14,816
Total current assets		733,247	254,062
Note receivable - Anadarko		260,000	260,000
Property, plant and equipment
Cost		8,272,083	7,871,102
Less accumulated depreciation		2,208,536	2,140,211
Net property, plant and equipment		6,063,547	5,730,891
Goodwill		416,160	416,160
Other intangible assets		768,162	775,269
Equity investments		557,681	566,211
Other assets	[3]	14,525	11,757
Total assets		8,813,322	8,014,350
Current liabilities
Accounts and imbalance payables	[4]	360,028	349,801
Accrued ad valorem taxes		38,871	26,633
Accrued liabilities	[5]	78,798	47,899
Total current liabilities		477,697	424,333
Long-term liabilities
Long-term debt		4,176,346	3,464,712
Deferred income taxes		8,592	7,409
Asset retirement obligations		147,082	143,394
Other liabilities	[6]	128,757	3,491
Total long-term liabilities		4,460,777	3,619,006
Total liabilities		4,938,474	4,043,339
Equity and partners' capital
General partner units (2,583,068 units issued and outstanding at March 31, 2018, and December 31, 2017)		185,812	179,232
Total partners' capital		3,812,529	3,909,282
Noncontrolling interest		62,319	61,729
Total equity and partners' capital		3,874,848	3,971,011
Total liabilities, equity and partners' capital		8,813,322	8,014,350
Common Units [Member]
Equity and partners' capital
Common units and Class C units		2,842,612	2,950,010
Class C Units [Member]
Equity and partners' capital
Common units and Class C units	[7]	$ 784,105	$ 780,040
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $56.3 million and $36.3 million as of March 31, 2018, and December 31, 2017, respectively.
[2]	Other current assets includes affiliate amounts of $5.7 million and zero as of March 31, 2018, and December 31, 2017, respectively.
[3]	Other assets includes affiliate amounts of $0.2 million and zero as of March 31, 2018, and December 31, 2017, respectively.
[4]	Accounts and imbalance payables includes affiliate amounts of $0.1 million and $0.3 million as of March 31, 2018, and December 31, 2017, respectively.
[5]	Accrued liabilities includes affiliate amounts of $2.1 million and $0.2 million as of March 31, 2018, and December 31, 2017, respectively.
[6]	Other liabilities includes affiliate amounts of $42.4 million and $0.7 million as of March 31, 2018, and December 31, 2017, respectively.
[7]	The Class C units will convert into common units on a one-for-one basis on March 1, 2020, unless the Partnership elects to convert such units earlier or Anadarko extends the conversion date. See Note 5.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
General partner units issued		2,583,068	2,583,068
General partner units outstanding		2,583,068	2,583,068
Accounts receivable, net	[1]	$ 189,074	$ 160,432
Other current assets	[2]	22,747	14,816
Other assets	[3]	14,525	11,757
Accounts and imbalance payables	[4]	360,028	349,801
Accrued liabilities	[5]	78,798	47,899
Other liabilities	[6]	128,757	3,491
Affiliates [Member]
Accounts receivable, net		56,300	36,300
Other current assets		5,700	0
Other assets		200	0
Accounts and imbalance payables		100	300
Accrued liabilities		2,100	200
Other liabilities		$ 42,400	$ 700
Common Units [Member]
Units issued		152,602,105	152,602,105
Units outstanding		152,602,105	152,602,105
Class C Units [Member]
Units issued		13,505,277	13,243,883
Units outstanding		13,505,277	13,243,883
Class C units, common units issued upon conversion		1
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $56.3 million and $36.3 million as of March 31, 2018, and December 31, 2017, respectively.
[2]	Other current assets includes affiliate amounts of $5.7 million and zero as of March 31, 2018, and December 31, 2017, respectively.
[3]	Other assets includes affiliate amounts of $0.2 million and zero as of March 31, 2018, and December 31, 2017, respectively.
[4]	Accounts and imbalance payables includes affiliate amounts of $0.1 million and $0.3 million as of March 31, 2018, and December 31, 2017, respectively.
[5]	Accrued liabilities includes affiliate amounts of $2.1 million and $0.2 million as of March 31, 2018, and December 31, 2017, respectively.
[6]	Other liabilities includes affiliate amounts of $42.4 million and $0.7 million as of March 31, 2018, and December 31, 2017, respectively.

Consolidated Statement of Equit

Consolidated Statement of Equity and Partners' Capital - 3 months ended Mar. 31, 2018 - USD ($) $ in Thousands		Total	Common Units [Member]	Class C Units [Member]	General Partner Units [Member]	Noncontrolling Interest [Member]
Balance at Dec. 31, 2017		$ 3,971,011	$ 2,950,010	$ 780,040	$ 179,232	$ 61,729
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		152,348	59,133	6,791	83,439	2,985
Above-market component of swap agreements with Anadarko	[1]	14,282	14,282
Amortization of beneficial conversion feature of Class C units		0	(810)	810
Distributions to noncontrolling interest owner		(3,353)				(3,353)
Distributions to unitholders		(216,586)	(140,394)		(76,192)
Contributions of equity-based compensation from Anadarko		1,464	1,435		29
Other		91	91
Balance at Mar. 31, 2018		3,874,848	2,842,612	784,105	185,812	62,319
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect of accounting change	[2]	$ (44,409)	$ (41,135)	$ (3,536)	$ (696)	$ 958
[1]	See Note 6.
[2]	See Note 1.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Cash flows from operating activities
Net income (loss)		$ 152,348		$ 103,991
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		76,842		69,702
Impairments		148		164,742
Non-cash equity-based compensation expense		1,563		1,209
Deferred income taxes		1,331		3,128
Accretion and amortization of long-term obligations, net		1,378		1,101
Equity income, net – affiliates	[1]	(20,424)		(19,461)
Distributions from equity investment earnings – affiliates		20,941		19,114
(Gain) loss on divestiture and other, net	[2],[3]	(116)		(119,487)
Lower of cost or market inventory adjustments		143		45
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		(28,648)		(1,513)
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		27,075		(29,940)
Change in other items, net		9,015		(15)
Net cash provided by operating activities		241,596		192,616
Cash flows from investing activities
Capital expenditures		(302,297)		(125,944)
Distributions from equity investments in excess of cumulative earnings – affiliates		8,013	[4]	3,453
Proceeds from property insurance claims		0		24,000
Net cash used in investing activities		(294,168)		(252,434)
Cash flows from financing activities
Borrowings, net of debt issuance costs		1,337,525		(11)
Repayments of debt		(630,000)		0
Increase (decrease) in outstanding checks		(6,684)		1,024
Proceeds from the issuance of common units, net of offering expenses		0		(158)
Distributions to unitholders	[5]	(216,586)		(185,565)
Distributions to noncontrolling interest owner		(3,353)		(3,370)
Net contributions from (distributions to) Anadarko		0		(14)
Above-market component of swap agreements with Anadarko	[5]	14,282		12,297
Net cash provided by (used in) financing activities		495,184		(175,797)
Net increase (decrease) in cash and cash equivalents		442,612		(235,615)
Cash and cash equivalents at beginning of period		78,814		357,925
Cash and cash equivalents at end of period		521,426		122,310
Supplemental disclosures
Accretion expense and revisions to the Deferred purchase price obligation – Anadarko		0		(4,094)
Interest paid, net of capitalized interest		28,514		28,656
Taxes paid (reimbursements received)		(87)		189
Accrued capital expenditures		229,484		85,280
Fair value of properties and equipment from non-cash third party transactions	[6]	0		548,628
Affiliates [Member]
Cash flows from investing activities
Contributions in aid of construction costs from affiliates		0		1,310
Cash flows from financing activities
Distributions to unitholders	[7]	(124,164)		(103,123)
Third Parties [Member]
Cash flows from investing activities
Acquisitions		0		(155,287)
Proceeds from the sale of assets		$ 116		$ 34
[1]	Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, 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 three months ended March 31, 2017. See Note 1.
[3]	Includes losses related to an incident at the DBM complex for the three months ended March 31, 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 the partnership agreement (see Note 4 and Note 5).

Description of Business and Bas

Description of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION General. Western Gas Partners, LP is a growth-oriented Delaware master limited partnership (“MLP”) formed by Anadarko Petroleum Corporation in 2007 to acquire, own, develop and operate midstream assets. For purposes of these consolidated financial statements, the “Partnership” refers to Western Gas Partners, LP and its subsidiaries. The Partnership’s general partner, Western Gas Holdings, LLC (the “general partner”), is owned by Western Gas Equity Partners, LP (“WGP”), a Delaware MLP formed by Anadarko Petroleum Corporation in September 2012 to own the Partnership’s general partner, as well as a significant limited partner interest in the Partnership. WGP has no independent operations or material assets other than owning the partnership interests in the Partnership (see Holdings of Partnership equity in Note 5 ). Western Gas Equity Holdings, LLC is WGP’s general partner and is a wholly owned subsidiary of Anadarko Petroleum Corporation. “Anadarko” refers to Anadarko Petroleum Corporation and its subsidiaries, excluding the Partnership and the general partner, and “affiliates” refers to subsidiaries of Anadarko, excluding the Partnership, 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”) and Front Range Pipeline LLC (“FRP”). 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. The Partnership 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, the Partnership also buys and sells natural gas, NGLs and condensate on behalf of itself and as agent for its customers under certain of its contracts. The Partnership provides these midstream services for Anadarko, as well as for third-party producers and customers. As of March 31, 2018 , the Partnership’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 — 1 (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. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Basis of presentation. The following table outlines the Partnership’s ownership interests and the accounting method of consolidation used in the Partnership’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 % 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 the Partnership exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to the Partnership’s share of average throughput for these investments. (2) The Partnership proportionately consolidates its 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 interest in the consolidated financial statements. 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 the Partnership and entities in which it holds a controlling financial interest. 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 the Partnership’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. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Presentation of Partnership assets. The term “Partnership assets” includes both the assets owned and the interests accounted for under the equity method by the Partnership as of March 31, 2018 (see Note 8 ). Because Anadarko controls the Partnership through its control of WGP, which owns the Partnership’s entire general partner interest, each acquisition of Partnership assets from Anadarko has been considered a transfer of net assets between entities under common control. As such, the Partnership assets acquired from Anadarko were initially recorded at Anadarko’s historic carrying value, which did not correlate to the total acquisition price paid by the Partnership. Further, after an acquisition of Partnership assets from Anadarko, the Partnership may be required to recast its financial statements to include the activities of such Partnership assets from the date of common control. For those periods requiring recast, the consolidated financial statements for periods prior to the Partnership’s acquisition of the Partnership 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 the Partnership had owned the Partnership assets during the periods reported. Net income (loss) attributable to the Partnership assets acquired from Anadarko for periods prior to the Partnership’s acquisition of the Partnership 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 furnished 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. Insurance recoveries. In December 2015, there was an initial fire and secondary explosion at the processing facility within the Delaware Basin Midstream, LLC (“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 three months ended March 31, 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 the Partnership’s estimate of the amount that would be recovered under the property insurance claim based on further discussions with insurers. During the three months ended March 31, 2017 , the Partnership received $29.8 million in cash proceeds from insurers, including $5.8 million in proceeds from business interruption insurance claims and $24.0 million in proceeds from property insurance claims. Recently adopted accounting standards. 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. The Partnership adopted this ASU using a retrospective approach on January 1, 2018, and the adoption did not impact the consolidated financial statements. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Revenue from contracts with customers (Topic 606). The Partnership adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) on January 1, 2018, using the modified retrospective method applied to 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, the Partnership 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, 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. Under Topic 606, the Partnership recognizes revenue associated with upfront or limited-term fees over the expected period of customer benefit, which is generally the life of the related properties. In addition, deficiency fees are estimated and recognized during the performance period as the services are performed for the customer’s delivered volumes. Under Topic 606, differences between Service revenues – fee based recognized and amounts billed to customers are recognized as contract assets or contract liabilities, as appropriate. This results in a change in the timing of revenue and changes to net income as a result of the revenue contract’s consideration provisions. • Cost of service rate adjustments. Under Topic 605, revenue was recognized based on the amounts billed to customers each period. 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. • Percent-of-proceeds gathering / processing. Under Topic 605, the Partnership recognized cost of product expense when the product was purchased from a producer to whom it provides services, and the Partnership 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 the Partnership is acting as the producer’s agent in the product sale. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) • Noncash consideration - keep-whole and percent-of-product agreements. Under Topic 605, the Partnership recognized revenues only upon the sale of the related products. Under Topic 606, the Partnership recognizes Service revenues – product based 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. Under Topic 606, revenue from product sales is recognized, along with cost of product expense related to the sale, when the product is sold to Anadarko or a third party. • 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 the Partnership. The following tables summarize the impact of adopting Topic 606 on the impacted line items within the consolidated statement 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 $ 338,419 $ 342,338 $ (3,919 ) Service revenues – product based 22,593 — 22,593 Product sales 75,937 292,291 (216,354 ) Expenses Cost of product 77,799 274,966 (197,167 ) Operation and maintenance 88,279 88,139 140 Depreciation and amortization 76,842 76,153 689 Income tax (benefit) expense 1,502 1,509 (7 ) Net income attributable to noncontrolling interest 2,985 2,498 487 Net income (loss) attributable to Western Gas Partners, LP 149,363 151,185 (1,822 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) March 31, 2018 thousands As Reported Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Assets Other current assets $ 22,747 $ 16,909 $ 5,838 Net property, plant and equipment 6,063,547 5,977,144 86,403 Other assets 14,525 14,303 222 Liabilities Accrued liabilities 78,798 74,090 4,708 Deferred income taxes 8,592 8,746 (154 ) Other liabilities 128,757 2,553 126,204 Equity and partners’ capital Total equity and partners’ capital 3,874,848 3,913,143 (38,295 ) 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. The Partnership plans to make certain elections allowing the Partnership not to reassess contracts that commenced prior to adoption, to continue applying its current accounting policy for land easements and not to recognize ROU assets or lease liabilities for short-term leases. The Partnership continues to review contracts in its portfolio of leased assets to assess the impact of adopting this ASU, which is expected to primarily affect other assets and other long-term liabilities. To facilitate compliance with this ASU, the Partnership is implementing new accounting software and continuing to evaluate its systems, processes, and internal controls during 2018. The Partnership will adopt this ASU on January 1, 2019, using a modified retrospective approach for all comparative periods presented according to the ASU as it is currently written. Revenue and cost of product. Upon adoption of the new revenue recognition standard on January 1, 2018 (discussed in Recently adopted accounting standards ), the Partnership changed its accounting policy for revenue recognition as described below. The Partnership provides gathering, processing, treating, transportation and disposal services pursuant to a variety of contracts. Under these arrangements, the Partnership 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. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) 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 the Partnership’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, the Partnership 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. The Partnership 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 the Partnership’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. The Partnership 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 the Partnership, 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. The Partnership 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	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	2. REVENUE FROM CONTRACTS WITH CUSTOMERS The following table summarizes the Partnership’s revenue from contracts with customers: thousands Three Months Ended Revenue from customers Service revenues – fee based $ 338,419 Service revenues – product based 22,593 Product sales 77,180 Total revenue from customers 438,192 Revenue from other than customers Net gains (losses) on commodity price swap agreements (1,243 ) Other 219 Total revenues and other $ 437,168 Contract balances. Receivables from customers, which are included in Accounts receivable, net on the consolidated balance sheets were $252.3 million and $244.4 million as of March 31, 2018 , and December 31, 2017, respectively. Contract assets primarily relate to accrued deficiency fees the Partnership 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 (2,494 ) Additional estimated revenues recognized 3,425 Balance at March 31, 2018 $ 6,060 Contract assets at March 31, 2018 Other current assets $ 5,838 Other assets 222 Total contract assets from contracts with customers $ 6,060 2. REVENUE FROM CONTRACTS WITH CUSTOMERS (CONTINUED) 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 28,538 Revenues recognized during the period that were included in the adoption effect (1,027 ) Balance at March 31, 2018 $ 148,228 Contract liabilities at March 31, 2018 Accrued liabilities $ 22,024 Other liabilities 126,204 Total contract liabilities from contracts with customers $ 148,228 Transaction price allocated to remaining performance obligations. Revenues expected to be recognized from certain performance obligations that are unsatisfied (or partially unsatisfied) as of March 31, 2018 , are reflected in the following table. The Partnership 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 consolidated 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 $ 267,905 2019 440,723 2020 496,050 2021 469,728 2022 460,992 Thereafter 1,697,687 Total $ 3,833,085

Acquisitions and Divestitures

Acquisitions and Divestitures	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Acquisitions and Divestitures	3. ACQUISITIONS AND DIVESTITURES Property exchange. On March 17, 2017, the Partnership 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) the Partnership’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”). The Partnership 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 the Partnership’s agreement with Anadarko to settle its deferred purchase price obligation early, the consideration that would have been paid by the Partnership for the March 2015 acquisition of DBJV from Anadarko consisted of a cash payment to Anadarko due on March 31, 2020. In May 2017, the Partnership 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.

Partnership Distributions

Partnership Distributions	3 Months Ended
	Mar. 31, 2018
Distributions Made to Members or Limited Partners [Abstract]
Partnership Distributions	4. PARTNERSHIP DISTRIBUTIONS The partnership agreement requires the Partnership to distribute all of its available cash (as defined in the partnership agreement) to unitholders of record on the applicable record date within 45 days of the end of each quarter. The Board of Directors of the Partnership’s general partner (the “Board of Directors”) declared the following cash distributions to the Partnership’s common and general partner 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 $ 0.875 $ 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 (1) $ 0.935 $ 221,133 May 2018 (1) The Board of Directors declared a cash distribution to the Partnership’s unitholders for the first quarter of 2018 of $0.935 per unit, or $221.1 million in aggregate, including incentive distributions, but excluding distributions on Class C units (see Class C unit distributions below). The cash distribution is payable on May 14, 2018 , to unitholders of record at the close of business on May 2, 2018 . 4. PARTNERSHIP DISTRIBUTIONS (CONTINUED) Available cash. The amount of available cash (as defined in the partnership agreement) generally is all cash on hand at the end of the quarter, plus, at the discretion of the general partner, working capital borrowings made subsequent to the end of such quarter, less the amount of cash reserves established by the Partnership’s general partner to provide for the proper conduct of the Partnership’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 its unitholders and to its general partner 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. Class C unit distributions. The Class C units receive quarterly distributions at a rate equivalent to the Partnership’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 distributions of the Partnership’s available cash until they are converted into 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 the Partnership’s common units for the ten days immediately preceding the payment date for the common unit distribution, less a 6% discount. The Partnership records the PIK Class C unit distributions at fair value at the time of issuance. This Level 2 fair value measurement uses the Partnership’s unit price as a significant input in the determination of the fair value. See Note 5 for further discussion of the Class C units. Series A Preferred unit distributions. As further described in Note 5 , the Partnership issued Series A Preferred units representing limited partner interests in the Partnership 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 Series A Preferred units converted into common units on a one -for-one basis, and on May 2, 2017, all remaining Series A Preferred units converted into common units on a one -for-one basis. Such converted common units were entitled to distributions made to common unitholders with respect to the quarter during which the applicable conversion occurred and did not include a prorated Series A Preferred unit distribution. For the quarter ended March 31, 2017, the Series A Preferred unitholders received an aggregate cash distribution of $7.5 million (paid in May 2017). General partner interest and incentive distribution rights. As of March 31, 2018 , the general partner was entitled to 1.5% of all quarterly distributions that the Partnership 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 the general partner may receive on common units that it may acquire.

Equity and Partners' Capital

Equity and Partners' Capital	3 Months Ended
	Mar. 31, 2018
Partners' Capital Notes [Abstract]
Equity and Partners' Capital	5. EQUITY AND PARTNERS’ CAPITAL Equity offerings. In July 2017, the Partnership filed a registration statement with the SEC for the issuance of up to an aggregate of $500.0 million of common units pursuant to a new continuous offering program that has not yet been initiated. Class C units. In November 2014, the Partnership 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 the acquisition of DBM. When issued, the Class C units were scheduled to convert into common units on a one -for-one basis on December 31, 2017. In February 2017, Anadarko elected to extend the conversion date of the Class C units to March 1, 2020. The Partnership can elect to convert the Class C units earlier or Anadarko can extend the conversion date again. The Class C units were issued at a discount to the then-current market price of the common units into which they are convertible. This discount, totaling $34.8 million , represents a beneficial conversion feature, and at issuance, was reflected as an increase in common unitholders’ capital and a decrease in Class C unitholder capital to reflect the fair value of the Class C units at issuance. The beneficial conversion feature is considered a non-cash distribution that is recognized from the date of issuance through the date of conversion, resulting in an increase in Class C unitholder capital and a decrease in common unitholders’ capital as amortized. The beneficial conversion feature is amortized assuming the extended conversion date of March 1, 2020, using the effective yield method. The impact of the beneficial conversion feature amortization is included in the calculation of earnings per unit. Series A Preferred units. In 2016, the Partnership issued 21,922,831 Series A Preferred units to private investors. The Series A Preferred units were issued at a discount to the then-current market price of the common units into which they were convertible, representing a beneficial conversion feature at issuance. The impact of the beneficial conversion feature amortization was included in the calculation of earnings per unit. For the three months ended March 31, 2017 , the amortization for the beneficial conversion feature of the Series A Preferred units was $48.1 million . Pursuant to an agreement between the Partnership and the holders of the Series A Preferred units, 50% of the Series A Preferred units converted into common units on a one -for-one basis on March 1, 2017, and all remaining Series A Preferred units converted into common units on a one -for-one basis on May 2, 2017. The Partnership has an effective registration statement with the SEC relating to the public resale of the common units issued upon conversion of the Series A Preferred units. Partnership interests. The Partnership’s common units are listed on the New York Stock Exchange under the symbol “WES.” The following table summarizes the Partnership’s units issued during the three months ended March 31, 2018 : Common Units Class C Units 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 — 261,394 — 261,394 Balance at March 31, 2018 152,602,105 13,505,277 2,583,068 168,690,450 5. EQUITY AND PARTNERS’ CAPITAL (CONTINUED) Holdings of Partnership equity. As of March 31, 2018 , WGP held 50,132,046 common units, representing a 29.7% limited partner interest in the Partnership, and, through its ownership of the general partner, WGP indirectly held 2,583,068 general partner units, representing a 1.5% general partner interest in the Partnership, and 100% of the IDRs. As of March 31, 2018 , other subsidiaries of Anadarko collectively held 2,011,380 common units and 13,505,277 Class C units, representing an aggregate 9.2% limited partner interest in the Partnership. As of March 31, 2018 , the public held 100,458,679 common units, representing the remaining 59.6% limited partner interest in the Partnership. Net income (loss) per common unit. Net income (loss) attributable to the Partnership assets acquired from Anadarko for periods prior to the Partnership’s acquisition of the Partnership assets is not allocated to the unitholders for purposes of calculating net income (loss) per common unit. Net income (loss) attributable to Western Gas Partners, LP earned on and subsequent to the date of acquisition of the Partnership assets is allocated as follows: General partner. The general partner’s allocation is equal to cash distributions plus its portion of undistributed earnings or losses. Specifically, net income equal to the amount of available cash (as defined by the partnership agreement) is allocated to the general partner consistent with actual cash distributions and capital account allocations, including incentive distributions. Undistributed earnings (net income in excess of distributions) or undistributed losses (available cash in excess of net income) are then allocated to the general partner in accordance with its weighted-average ownership percentage during each period. Series A Preferred unitholders. The Series A Preferred units were not considered a participating security as they only had distribution rights up to the specified per-unit quarterly distribution and had no rights to the Partnership’s undistributed earnings and losses. As such, the Series A Preferred unitholders’ allocation was equal to their cash distribution plus the amortization of the Series A Preferred units beneficial conversion feature (see Series A Preferred units above). Common and Class C unitholders. The Class C units are considered a participating security because they participate in distributions with common units according to a predetermined formula (see Note 4 ). The common and Class C unitholders’ allocation is equal to their cash distributions plus their respective portions of undistributed earnings or losses. Specifically, net income equal to the amount of available cash (as defined by the partnership agreement) is allocated to the common and Class C unitholders consistent with actual cash distributions and capital account allocations. Undistributed earnings or undistributed losses are then allocated to the common and Class C unitholders in accordance with their respective weighted-average ownership percentages during each period. The common unitholder allocation also includes the impact of the amortization of the Series A Preferred units and Class C units beneficial conversion features. The Class C unitholder allocation is similarly impacted by the amortization of the Class C units beneficial conversion feature (see Class C units above). 5. EQUITY AND PARTNERS’ CAPITAL (CONTINUED) Calculation of net income (loss) per unit. Basic net income (loss) per common unit is calculated by dividing the net income (loss) attributable to common unitholders by the weighted-average number of common units outstanding during the period. The common units issued in connection with acquisitions and equity offerings are included on a weighted-average basis for periods they were outstanding. Diluted net income (loss) per common unit is calculated by dividing the sum of (i) the net income (loss) attributable to common units adjusted for distributions on the Series A Preferred units and a reallocation of the common and Class C limited partners’ interest in net income (loss) assuming, prior to the actual conversion, conversion of the Series A Preferred units into common units, and (ii) the net income (loss) attributable to the Class C units as a participating security, by the sum of the weighted-average number of common units outstanding plus the dilutive effect of (i) the weighted-average number of outstanding Class C units and (ii) the weighted-average number of common units outstanding assuming, prior to the actual conversion, conversion of the Series A Preferred units. The following table illustrates the Partnership’s calculation of net income (loss) per common unit: Three Months Ended thousands except per-unit amounts 2018 2017 Net income (loss) attributable to Western Gas Partners, LP $ 149,363 $ 101,889 Series A Preferred units interest in net (income) loss (1) — (28,174 ) General partner interest in net (income) loss (83,439 ) (68,162 ) Common and Class C limited partners’ interest in net income (loss) $ 65,924 $ 5,553 Net income (loss) allocable to common units (1) $ 58,323 $ 1,714 Net income (loss) allocable to Class C units (1) 7,601 3,839 Common and Class C limited partners’ interest in net income (loss) $ 65,924 $ 5,553 Net income (loss) per unit Common units – basic and diluted (2) $ 0.38 $ 0.01 Weighted-average units outstanding Common units – basic and diluted 152,602 134,448 Excluded due to anti-dilutive effect: Class C units (2) 13,380 12,452 Series A Preferred units assuming conversion to common units (2) — 18,147 (1) Adjusted to reflect amortization of the beneficial conversion features. (2) The impact of Class C units would be anti-dilutive for all periods presented and the conversion of Series A Preferred units would be anti-dilutive for the three months ended March 31, 2017 . On March 1, 2017, 50% of the outstanding Series A Preferred units converted into common units on a one -for-one basis, and on May 2, 2017, all remaining Series A Preferred units converted into common units on a one -for-one basis.

Transactions with Affiliates

Transactions with Affiliates	3 Months Ended
	Mar. 31, 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 the Partnership from services provided to Anadarko as well as from the sale of residue and NGLs to Anadarko. In addition, the Partnership purchases natural gas 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 the Partnership assets, whether in providing services to affiliates or to third parties, including field labor, measurement and analysis, and other disbursements. A portion of the Partnership’s general and administrative expenses is paid by Anadarko, which results in affiliate transactions pursuant to the reimbursement provisions of the Partnership’s omnibus agreement. 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 Partnership’s acquisition of the Partnership 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 the Partnership assets. Subsequent to the acquisition of Partnership 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 the Partnership. Note receivable - Anadarko. Concurrently with the closing of the Partnership’s May 2008 initial public offering, the Partnership 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 $316.2 million and $325.2 million at March 31, 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. Commodity price swap agreements. The Partnership 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. The Partnership’s net gains (losses) on commodity price swap agreements were $(1.2) million and $(0.5) million for three months ended March 31, 2018 and 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 ). 6. TRANSACTIONS WITH AFFILIATES (CONTINUED) 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. The Partnership also records a capital contribution from Anadarko in the Partnership’s 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 three months ended March 31, 2018 , the capital contribution from Anadarko was $14.3 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. Gathering and processing agreements. The Partnership has significant gathering and processing arrangements with affiliates of Anadarko on a majority of its systems. The Partnership’s natural gas gathering, treating and transportation throughput (excluding equity investment throughput) attributable to production owned or controlled by Anadarko was 36% and 32% for the three months ended March 31, 2018 and 2017 , respectively. The Partnership’s natural gas processing throughput (excluding equity investment throughput) attributable to production owned or controlled by Anadarko was 36% and 49% for the three months ended March 31, 2018 and 2017 , respectively. The Partnership’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 63% and 54% for the three months ended March 31, 2018 and 2017 , respectively. 6. TRANSACTIONS WITH AFFILIATES (CONTINUED) Commodity purchase and sale agreements. The Partnership sells a significant amount of its natural gas, condensate and NGLs to Anadarko Energy Services Company (“AESC”), Anadarko’s marketing affiliate. In addition, the Partnership purchases natural gas, condensate and NGLs from AESC pursuant to purchase agreements. The Partnership’s purchase and sale agreements with AESC are generally one-year contracts, subject to annual renewal. WES LTIP. The general partner 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 the Partnership. 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 March 31, 2018 and 2017 . Anadarko Incentive Plan. General and administrative expenses included $2.1 million and $1.2 million for the three months ended March 31, 2018 and 2017, respectively, of equity-based compensation expense, allocated to the Partnership by Anadarko, for awards granted to the executive officers of the general partner and other employees under the Anadarko Petroleum Corporation 2012 Omnibus Incentive Compensation Plan (“Anadarko Incentive Plan”). Of this amount, $1.5 million is reflected as contributions to partners’ capital in the Partnership’s consolidated statement of equity and partners’ capital for the three months ended March 31, 2018 . Contributions in aid of construction costs from affiliates. On certain of the Partnership’s capital projects, Anadarko is obligated to reimburse the Partnership 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. 6. TRANSACTIONS WITH AFFILIATES (CONTINUED) Summary of affiliate transactions. The following table summarizes material affiliate transactions: Three Months Ended thousands 2018 2017 Revenues and other (1) $ 241,062 $ 315,155 Equity income, net – affiliates (1) 20,424 19,461 Cost of product (1) 20,244 15,988 Operation and maintenance (2) 20,248 17,089 General and administrative (3) 11,614 9,535 Operating expenses 52,106 42,612 Interest income (4) 4,225 4,225 Interest expense (5) — 71 Distributions to unitholders (6) 124,164 103,123 Above-market component of swap agreements with Anadarko 14,282 12,297 (1) Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, 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 Partnership assets, as well as expenses incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets. (3) Represents general and administrative expense incurred on and subsequent to the date of the acquisition of Partnership assets, as well as a management services fee for reimbursement of expenses incurred by Anadarko for periods prior to the acquisition of the Partnership assets by the Partnership. These amounts include equity-based compensation expense allocated to the Partnership by Anadarko (see WES LTIP and Anadarko Incentive Plan within this Note 6 ). (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 distributions paid under the partnership agreement (see Note 4 and Note 5 ). Concentration of credit risk. Anadarko was the only customer from whom revenues exceeded 10% of the Partnership’s consolidated revenues for all periods presented in the consolidated statements of operations.

Property, Plant and Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 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 March 31, 2018 December 31, 2017 Land n/a $ 4,449 $ 4,450 Gathering systems and processing complexes 3 to 47 years 7,305,279 7,114,701 Pipelines and equipment 15 to 45 years 137,765 137,644 Assets under construction n/a 794,012 577,914 Other 3 to 40 years 30,578 36,393 Total property, plant and equipment 8,272,083 7,871,102 Accumulated depreciation 2,208,536 2,140,211 Net property, plant and equipment $ 6,063,547 $ 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 three months ended March 31, 2018 , the Partnership recognized impairments of $0.1 million . During the year ended December 31, 2017, the Partnership 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	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	8. EQUITY INVESTMENTS The following table presents the activity in the Partnership’s equity investments for the three months ended March 31, 2018: thousands Fort White Rendezvous Mont TEG TEP FRP Total Balance at December 31, 2017 $ 7,030 $ 44,945 $ 42,528 $ 110,299 $ 15,879 $ 178,975 $ 166,555 $ 566,211 Investment earnings (loss), net of amortization 144 2,673 225 7,090 1,066 4,417 4,809 20,424 Distributions (144 ) (2,527 ) (710 ) (7,100 ) (1,127 ) (4,480 ) (4,853 ) (20,941 ) Distributions in excess of cumulative earnings (1) (741 ) (1,228 ) (1,162 ) (1,325 ) (20 ) (2,168 ) (1,369 ) (8,013 ) Balance at March 31, 2018 $ 6,289 $ 43,863 $ 40,881 $ 108,964 $ 15,798 $ 176,744 $ 165,142 $ 557,681 (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	3 Months Ended
	Mar. 31, 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 March 31, 2018 December 31, 2017 Trade receivables, net $ 188,550 $ 160,387 Other receivables, net 524 45 Total accounts receivable, net $ 189,074 $ 160,432 A summary of other current assets is as follows: thousands March 31, 2018 December 31, 2017 Natural gas liquids inventory $ 9,275 $ 10,788 Imbalance receivables 6,293 1,640 Prepaid insurance 1,341 2,388 Contract assets 5,838 — Total other current assets $ 22,747 $ 14,816 A summary of accrued liabilities is as follows: thousands March 31, 2018 December 31, 2017 Accrued interest expense $ 50,022 $ 40,632 Short-term asset retirement obligations 1,339 2,304 Short-term remediation and reclamation obligations 833 833 Income taxes payable 2,666 2,495 Contract liabilities 22,024 — Other 1,914 1,635 Total accrued liabilities $ 78,798 $ 47,899

Debt and Interest Expense

Debt and Interest Expense	3 Months Ended
	Mar. 31, 2018
Debt Instruments [Abstract]
Debt and Interest Expense	10. DEBT AND INTEREST EXPENSE At March 31, 2018 , the Partnership’s debt consisted of 2.600% Senior Notes due 2018 (the “2018 Notes”), 5.375% Senior Notes due 2021 (the “2021 Notes”), 4.000% Senior Notes due 2022 (the “2022 Notes”), 3.950% Senior Notes due 2025 (the “2025 Notes”), 4.650% Senior Notes due 2026 (the “2026 Notes”), 4.500% Senior Notes due 2028 (the “2028 Notes”), 5.450% Senior Notes due 2044 (the “2044 Notes”) and 5.300% Senior Notes due 2048 (the “2048 Notes”). The following table presents the Partnership’s outstanding debt: March 31, 2018 December 31, 2017 thousands Principal Carrying Value Fair Value (1) Principal Carrying Value Fair Value (1) 2018 Notes $ 350,000 $ 349,810 $ 349,542 $ 350,000 $ 349,684 $ 350,631 2021 Notes 500,000 496,095 522,069 500,000 495,815 530,647 2022 Notes 670,000 668,906 670,857 670,000 668,849 684,043 2025 Notes 500,000 492,120 487,240 500,000 491,885 500,885 2026 Notes 500,000 495,360 508,551 500,000 495,245 520,144 2028 Notes 400,000 394,285 401,807 — — — 2044 Notes 600,000 593,262 605,816 600,000 593,234 637,827 2048 Notes 700,000 686,508 698,234 — — — RCF — — — 370,000 370,000 370,000 Total long-term debt $ 4,220,000 $ 4,176,346 $ 4,244,116 $ 3,490,000 $ 3,464,712 $ 3,594,177 (1) Fair value is measured using the market approach and Level 2 inputs. Debt activity. The following table presents the debt activity of the Partnership for the three months ended March 31, 2018 : thousands Carrying Value Balance at December 31, 2017 $ 3,464,712 RCF borrowings 260,000 Issuance of 2028 Notes 400,000 Issuance of 2048 Notes 700,000 Repayments of RCF borrowings (630,000 ) Other (18,366 ) Balance at March 31, 2018 $ 4,176,346 Senior Notes. The 2018 Notes, which are due in August 2018, were classified as long-term debt on the consolidated balance sheet at March 31, 2018 , as the Partnership has the ability and intent to refinance these obligations using long-term debt. The 2028 Notes and 2048 Notes issued in March 2018 were offered at prices to the public 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 2028 Notes and 2048 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. A portion of the proceeds (net of underwriting discounts, original issue discounts and debt issuance costs) was used to repay amounts outstanding under the senior unsecured revolving credit facility (“RCF”) and for general partnership purposes, including to fund capital expenditures. At March 31, 2018 , the Partnership was in compliance with all covenants under the indentures governing its outstanding notes. 10. DEBT AND INTEREST EXPENSE (CONTINUED) Revolving credit facility. In February 2018, the Partnership entered into the five-year $1.5 billion RCF by amending and restating the $1.2 billion credit facility that was originally entered into in February 2014. The 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 the Partnership’s senior unsecured debt rating. The Partnership 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 March 31, 2018 , the Partnership had no outstanding RCF borrowings and $4.6 million in outstanding letters of credit, resulting in $1,495.4 million available borrowing capacity under the RCF. As of March 31, 2018 and 2017 , the interest rate on any outstanding RCF borrowings was 3.18% and 2.28% , respectively. The facility fee rate was 0.20% at March 31, 2018 and 2017 . At March 31, 2018 , the Partnership was in compliance with all covenants under the RCF. Interest expense. The following table summarizes the amounts included in interest expense: Three Months Ended thousands 2018 2017 Third parties Long-term debt $ (41,283 ) $ (34,619 ) Amortization of debt issuance costs and commitment fees (2,054 ) (1,630 ) Capitalized interest 4,054 816 Total interest expense – third parties (39,283 ) (35,433 ) Affiliates Deferred purchase price obligation – Anadarko (1) — (71 ) Total interest expense – affiliates — (71 ) Interest expense $ (39,283 ) $ (35,504 ) (1) See Note 3 for a discussion of the Deferred purchase price obligation - Anadarko.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 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 the Partnership, initiated an arbitration against SWEPI LP (“SWEPI”) for breach of a 2007 gas gathering agreement between it and DBJV (the “GGA”). Specifically, DBJV seeks to collect approximately $194.2 million in gathering fees under the GGA for the period January 1, 2016 to July 1, 2017. SWEPI disputes DBJV’s calculation of the cost of service based rate and filed a counterclaim for $14.9 million alleging overpayment of fees under the GGA for the years 2013 through 2015. The final arbitration hearing began April 30, 2018, and the Partnership expects to receive a decision by the end of the fourth quarter of 2018. Under the terms of the Property Exchange, the Partnership’s former joint venture partner in DBJV will owe 50% of any amounts to be paid, and have a right to 50% of any amounts received, by the Partnership as a result of this arbitration proceeding. Pursuant to an agreement between the parties, if the arbitrators determine that DBJV is owed an amount of money by SWEPI for underpaid gathering fees for the period from January 1, 2016 to July 1, 2017, that amount will be paid to DBJV over five years as a supplemental gathering fee under the currently effective gas gathering agreement between the parties. Any other amounts owed by either party will be paid in cash within ninety days of the conclusion of the arbitration. As part of the adoption of Topic 606 (see Note 1 ), during the first quarter of 2018, the Partnership 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. Any amounts awarded to DBJV under the arbitration would be recognized in the period the arbitration decision is received. The Partnership intends to vigorously prosecute its claims and vigorously defend the counterclaims asserted by SWEPI. Management does not believe the outcome of this proceeding will have a materially unfavorable effect on the Partnership’s financial condition, results of operations or cash flows. In addition, from time to time, the Partnership 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 the final disposition of which could have a material adverse effect on the Partnership’s financial condition, results of operations or cash flows. Other commitments. The Partnership 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 behalf of the Partnership, has entered into lease arrangements for corporate offices, shared field offices and equipment supporting the Partnership’s operations, for which Anadarko charges the Partnership lease expense. The leases for the corporate offices and shared field offices extend through 2028 and 2033, respectively. Lease expense charged to the Partnership associated with these lease arrangements was $13.8 million and $8.6 million for the three months ended March 31, 2018 and 2017 , respectively.

Description of Business and B19

Description of Business and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Consolidation policy	Basis of presentation. The following table outlines the Partnership’s ownership interests and the accounting method of consolidation used in the Partnership’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 % 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 the Partnership exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to the Partnership’s share of average throughput for these investments. (2) The Partnership proportionately consolidates its 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 interest in the consolidated financial statements. 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 the Partnership and entities in which it holds a controlling financial interest. 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 the Partnership’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.
Business combinations policy	Presentation of Partnership assets. The term “Partnership assets” includes both the assets owned and the interests accounted for under the equity method by the Partnership as of March 31, 2018 (see Note 8 ). Because Anadarko controls the Partnership through its control of WGP, which owns the Partnership’s entire general partner interest, each acquisition of Partnership assets from Anadarko has been considered a transfer of net assets between entities under common control. As such, the Partnership assets acquired from Anadarko were initially recorded at Anadarko’s historic carrying value, which did not correlate to the total acquisition price paid by the Partnership. Further, after an acquisition of Partnership assets from Anadarko, the Partnership may be required to recast its financial statements to include the activities of such Partnership assets from the date of common control. For those periods requiring recast, the consolidated financial statements for periods prior to the Partnership’s acquisition of the Partnership 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 the Partnership had owned the Partnership assets during the periods reported. Net income (loss) attributable to the Partnership assets acquired from Anadarko for periods prior to the Partnership’s acquisition of the Partnership 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 furnished 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. 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. The Partnership adopted this ASU using a retrospective approach on January 1, 2018, and the adoption did not impact the consolidated financial statements. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Revenue from contracts with customers (Topic 606). The Partnership adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) on January 1, 2018, using the modified retrospective method applied to 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, the Partnership 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, 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. Under Topic 606, the Partnership recognizes revenue associated with upfront or limited-term fees over the expected period of customer benefit, which is generally the life of the related properties. In addition, deficiency fees are estimated and recognized during the performance period as the services are performed for the customer’s delivered volumes. Under Topic 606, differences between Service revenues – fee based recognized and amounts billed to customers are recognized as contract assets or contract liabilities, as appropriate. This results in a change in the timing of revenue and changes to net income as a result of the revenue contract’s consideration provisions. • Cost of service rate adjustments. Under Topic 605, revenue was recognized based on the amounts billed to customers each period. 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. • Percent-of-proceeds gathering / processing. Under Topic 605, the Partnership recognized cost of product expense when the product was purchased from a producer to whom it provides services, and the Partnership 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 the Partnership is acting as the producer’s agent in the product sale. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) • Noncash consideration - keep-whole and percent-of-product agreements. Under Topic 605, the Partnership recognized revenues only upon the sale of the related products. Under Topic 606, the Partnership recognizes Service revenues – product based 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. Under Topic 606, revenue from product sales is recognized, along with cost of product expense related to the sale, when the product is sold to Anadarko or a third party. • 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 the Partnership. The following tables summarize the impact of adopting Topic 606 on the impacted line items within the consolidated statement 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 $ 338,419 $ 342,338 $ (3,919 ) Service revenues – product based 22,593 — 22,593 Product sales 75,937 292,291 (216,354 ) Expenses Cost of product 77,799 274,966 (197,167 ) Operation and maintenance 88,279 88,139 140 Depreciation and amortization 76,842 76,153 689 Income tax (benefit) expense 1,502 1,509 (7 ) Net income attributable to noncontrolling interest 2,985 2,498 487 Net income (loss) attributable to Western Gas Partners, LP 149,363 151,185 (1,822 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) March 31, 2018 thousands As Reported Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Assets Other current assets $ 22,747 $ 16,909 $ 5,838 Net property, plant and equipment 6,063,547 5,977,144 86,403 Other assets 14,525 14,303 222 Liabilities Accrued liabilities 78,798 74,090 4,708 Deferred income taxes 8,592 8,746 (154 ) Other liabilities 128,757 2,553 126,204 Equity and partners’ capital Total equity and partners’ capital 3,874,848 3,913,143 (38,295 ) 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. The Partnership plans to make certain elections allowing the Partnership not to reassess contracts that commenced prior to adoption, to continue applying its current accounting policy for land easements and not to recognize ROU assets or lease liabilities for short-term leases. The Partnership continues to review contracts in its portfolio of leased assets to assess the impact of adopting this ASU, which is expected to primarily affect other assets and other long-term liabilities. To facilitate compliance with this ASU, the Partnership is implementing new accounting software and continuing to evaluate its systems, processes, and internal controls during 2018. The Partnership will adopt this ASU on January 1, 2019, using a modified retrospective approach for all comparative periods presented according to the ASU as it is currently written.
Revenues 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 ), the Partnership changed its accounting policy for revenue recognition as described below. The Partnership provides gathering, processing, treating, transportation and disposal services pursuant to a variety of contracts. Under these arrangements, the Partnership 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. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) 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 the Partnership’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, the Partnership 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. The Partnership 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 the Partnership’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. The Partnership 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 the Partnership, 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. The Partnership 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. Net income (loss) attributable to the Partnership assets acquired from Anadarko for periods prior to the Partnership’s acquisition of the Partnership assets is not allocated to the unitholders for purposes of calculating net income (loss) per common unit. Net income (loss) attributable to Western Gas Partners, LP earned on and subsequent to the date of acquisition of the Partnership assets is allocated as follows: General partner. The general partner’s allocation is equal to cash distributions plus its portion of undistributed earnings or losses. Specifically, net income equal to the amount of available cash (as defined by the partnership agreement) is allocated to the general partner consistent with actual cash distributions and capital account allocations, including incentive distributions. Undistributed earnings (net income in excess of distributions) or undistributed losses (available cash in excess of net income) are then allocated to the general partner in accordance with its weighted-average ownership percentage during each period. Series A Preferred unitholders. The Series A Preferred units were not considered a participating security as they only had distribution rights up to the specified per-unit quarterly distribution and had no rights to the Partnership’s undistributed earnings and losses. As such, the Series A Preferred unitholders’ allocation was equal to their cash distribution plus the amortization of the Series A Preferred units beneficial conversion feature (see Series A Preferred units above). Common and Class C unitholders. The Class C units are considered a participating security because they participate in distributions with common units according to a predetermined formula (see Note 4 ). The common and Class C unitholders’ allocation is equal to their cash distributions plus their respective portions of undistributed earnings or losses. Specifically, net income equal to the amount of available cash (as defined by the partnership agreement) is allocated to the common and Class C unitholders consistent with actual cash distributions and capital account allocations. Undistributed earnings or undistributed losses are then allocated to the common and Class C unitholders in accordance with their respective weighted-average ownership percentages during each period. The common unitholder allocation also includes the impact of the amortization of the Series A Preferred units and Class C units beneficial conversion features. The Class C unitholder allocation is similarly impacted by the amortization of the Class C units beneficial conversion feature (see Class C units above). 5. EQUITY AND PARTNERS’ CAPITAL (CONTINUED) Calculation of net income (loss) per unit. Basic net income (loss) per common unit is calculated by dividing the net income (loss) attributable to common unitholders by the weighted-average number of common units outstanding during the period. The common units issued in connection with acquisitions and equity offerings are included on a weighted-average basis for periods they were outstanding. Diluted net income (loss) per common unit is calculated by dividing the sum of (i) the net income (loss) attributable to common units adjusted for distributions on the Series A Preferred units and a reallocation of the common and Class C limited partners’ interest in net income (loss) assuming, prior to the actual conversion, conversion of the Series A Preferred units into common units, and (ii) the net income (loss) attributable to the Class C units as a participating security, by the sum of the weighted-average number of common units outstanding plus the dilutive effect of (i) the weighted-average number of outstanding Class C units and (ii) the weighted-average number of common units outstanding assuming, prior to the actual conversion, conversion of the Series A Preferred units.

Description of Business and B20

Description of Business and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Assets and Investments Table	As of March 31, 2018 , the Partnership’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 — 1 (1) Includes the DBM water systems.
Ownership Interests and Method of Consolidation Table	The following table outlines the Partnership’s ownership interests and the accounting method of consolidation used in the Partnership’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 % 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 the Partnership exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to the Partnership’s share of average throughput for these investments. (2) The Partnership proportionately consolidates its 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 interest in the consolidated financial statements.
Impact of New Accounting Pronouncement Tables	The following tables summarize the impact of adopting Topic 606 on the impacted line items within the consolidated statement 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 $ 338,419 $ 342,338 $ (3,919 ) Service revenues – product based 22,593 — 22,593 Product sales 75,937 292,291 (216,354 ) Expenses Cost of product 77,799 274,966 (197,167 ) Operation and maintenance 88,279 88,139 140 Depreciation and amortization 76,842 76,153 689 Income tax (benefit) expense 1,502 1,509 (7 ) Net income attributable to noncontrolling interest 2,985 2,498 487 Net income (loss) attributable to Western Gas Partners, LP 149,363 151,185 (1,822 ) 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) March 31, 2018 thousands As Reported Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Assets Other current assets $ 22,747 $ 16,909 $ 5,838 Net property, plant and equipment 6,063,547 5,977,144 86,403 Other assets 14,525 14,303 222 Liabilities Accrued liabilities 78,798 74,090 4,708 Deferred income taxes 8,592 8,746 (154 ) Other liabilities 128,757 2,553 126,204 Equity and partners’ capital Total equity and partners’ capital 3,874,848 3,913,143 (38,295 )

Revenue from Contracts with C21

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Summary of Revenue from Contracts with Customers Table	The following table summarizes the Partnership’s revenue from contracts with customers: thousands Three Months Ended Revenue from customers Service revenues – fee based $ 338,419 Service revenues – product based 22,593 Product sales 77,180 Total revenue from customers 438,192 Revenue from other than customers Net gains (losses) on commodity price swap agreements (1,243 ) Other 219 Total revenues and other $ 437,168
Contract Assets and Liabilities Activity Tables	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 (2,494 ) Additional estimated revenues recognized 3,425 Balance at March 31, 2018 $ 6,060 Contract assets at March 31, 2018 Other current assets $ 5,838 Other assets 222 Total contract assets from contracts with customers $ 6,060 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 28,538 Revenues recognized during the period that were included in the adoption effect (1,027 ) Balance at March 31, 2018 $ 148,228 Contract liabilities at March 31, 2018 Accrued liabilities $ 22,024 Other liabilities 126,204 Total contract liabilities from contracts with customers $ 148,228
Expected Revenue Recognition from Satisfaction of Performance Obligations Table	Therefore, the following table represents only a small portion of expected future consolidated 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 $ 267,905 2019 440,723 2020 496,050 2021 469,728 2022 460,992 Thereafter 1,697,687 Total $ 3,833,085

Partnership Distributions (Tabl

Partnership Distributions (Tables)	3 Months Ended
	Mar. 31, 2018
Distributions Made to Members or Limited Partners [Abstract]
Cash Distributions Table	The Board of Directors of the Partnership’s general partner (the “Board of Directors”) declared the following cash distributions to the Partnership’s common and general partner 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 $ 0.875 $ 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 (1) $ 0.935 $ 221,133 May 2018 (1) The Board of Directors declared a cash distribution to the Partnership’s unitholders for the first quarter of 2018 of $0.935 per unit, or $221.1 million in aggregate, including incentive distributions, but excluding distributions on Class C units (see Class C unit distributions below). The cash distribution is payable on May 14, 2018 , to unitholders of record at the close of business on May 2, 2018 .

Equity and Partners' Capital (T

Equity and Partners' Capital (Tables)	3 Months Ended
	Mar. 31, 2018
Partners' Capital Notes [Abstract]
Partnership Interests Table	The following table summarizes the Partnership’s units issued during the three months ended March 31, 2018 : Common Units Class C Units 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 — 261,394 — 261,394 Balance at March 31, 2018 152,602,105 13,505,277 2,583,068 168,690,450
Calculation of Net Income (Loss) Per Unit Table	The following table illustrates the Partnership’s calculation of net income (loss) per common unit: Three Months Ended thousands except per-unit amounts 2018 2017 Net income (loss) attributable to Western Gas Partners, LP $ 149,363 $ 101,889 Series A Preferred units interest in net (income) loss (1) — (28,174 ) General partner interest in net (income) loss (83,439 ) (68,162 ) Common and Class C limited partners’ interest in net income (loss) $ 65,924 $ 5,553 Net income (loss) allocable to common units (1) $ 58,323 $ 1,714 Net income (loss) allocable to Class C units (1) 7,601 3,839 Common and Class C limited partners’ interest in net income (loss) $ 65,924 $ 5,553 Net income (loss) per unit Common units – basic and diluted (2) $ 0.38 $ 0.01 Weighted-average units outstanding Common units – basic and diluted 152,602 134,448 Excluded due to anti-dilutive effect: Class C units (2) 13,380 12,452 Series A Preferred units assuming conversion to common units (2) — 18,147 (1) Adjusted to reflect amortization of the beneficial conversion features. (2) The impact of Class C units would be anti-dilutive for all periods presented and the conversion of Series A Preferred units would be anti-dilutive for the three months ended March 31, 2017 . On March 1, 2017, 50% of the outstanding Series A Preferred units converted into common units on a one -for-one basis, and on May 2, 2017, all remaining Series A Preferred units converted into common units on a one -for-one basis.

Transactions with Affiliates (T

Transactions with Affiliates (Tables)	3 Months Ended
	Mar. 31, 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 Table	The following table summarizes material affiliate transactions: Three Months Ended thousands 2018 2017 Revenues and other (1) $ 241,062 $ 315,155 Equity income, net – affiliates (1) 20,424 19,461 Cost of product (1) 20,244 15,988 Operation and maintenance (2) 20,248 17,089 General and administrative (3) 11,614 9,535 Operating expenses 52,106 42,612 Interest income (4) 4,225 4,225 Interest expense (5) — 71 Distributions to unitholders (6) 124,164 103,123 Above-market component of swap agreements with Anadarko 14,282 12,297 (1) Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, 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 Partnership assets, as well as expenses incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets. (3) Represents general and administrative expense incurred on and subsequent to the date of the acquisition of Partnership assets, as well as a management services fee for reimbursement of expenses incurred by Anadarko for periods prior to the acquisition of the Partnership assets by the Partnership. These amounts include equity-based compensation expense allocated to the Partnership by Anadarko (see WES LTIP and Anadarko Incentive Plan within this Note 6 ). (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 distributions paid under the partnership agreement (see Note 4 and Note 5 ).

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018 December 31, 2017 Land n/a $ 4,449 $ 4,450 Gathering systems and processing complexes 3 to 47 years 7,305,279 7,114,701 Pipelines and equipment 15 to 45 years 137,765 137,644 Assets under construction n/a 794,012 577,914 Other 3 to 40 years 30,578 36,393 Total property, plant and equipment 8,272,083 7,871,102 Accumulated depreciation 2,208,536 2,140,211 Net property, plant and equipment $ 6,063,547 $ 5,730,891

Equity Investments (Tables)

Equity Investments (Tables)	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments Table	The following table presents the activity in the Partnership’s equity investments for the three months ended March 31, 2018: thousands Fort White Rendezvous Mont TEG TEP FRP Total Balance at December 31, 2017 $ 7,030 $ 44,945 $ 42,528 $ 110,299 $ 15,879 $ 178,975 $ 166,555 $ 566,211 Investment earnings (loss), net of amortization 144 2,673 225 7,090 1,066 4,417 4,809 20,424 Distributions (144 ) (2,527 ) (710 ) (7,100 ) (1,127 ) (4,480 ) (4,853 ) (20,941 ) Distributions in excess of cumulative earnings (1) (741 ) (1,228 ) (1,162 ) (1,325 ) (20 ) (2,168 ) (1,369 ) (8,013 ) Balance at March 31, 2018 $ 6,289 $ 43,863 $ 40,881 $ 108,964 $ 15,798 $ 176,744 $ 165,142 $ 557,681 (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)	3 Months Ended
	Mar. 31, 2018
Components Of Working Capital [Abstract]
Accounts Receivable, Net Table	A summary of accounts receivable, net is as follows: thousands March 31, 2018 December 31, 2017 Trade receivables, net $ 188,550 $ 160,387 Other receivables, net 524 45 Total accounts receivable, net $ 189,074 $ 160,432
Other Current Assets Table	A summary of other current assets is as follows: thousands March 31, 2018 December 31, 2017 Natural gas liquids inventory $ 9,275 $ 10,788 Imbalance receivables 6,293 1,640 Prepaid insurance 1,341 2,388 Contract assets 5,838 — Total other current assets $ 22,747 $ 14,816
Accrued Liabilities Table	A summary of accrued liabilities is as follows: thousands March 31, 2018 December 31, 2017 Accrued interest expense $ 50,022 $ 40,632 Short-term asset retirement obligations 1,339 2,304 Short-term remediation and reclamation obligations 833 833 Income taxes payable 2,666 2,495 Contract liabilities 22,024 — Other 1,914 1,635 Total accrued liabilities $ 78,798 $ 47,899

Debt and Interest Expense (Tabl

Debt and Interest Expense (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Instruments [Abstract]
Debt Outstanding and Debt Activity Tables	The following table presents the Partnership’s outstanding debt: March 31, 2018 December 31, 2017 thousands Principal Carrying Value Fair Value (1) Principal Carrying Value Fair Value (1) 2018 Notes $ 350,000 $ 349,810 $ 349,542 $ 350,000 $ 349,684 $ 350,631 2021 Notes 500,000 496,095 522,069 500,000 495,815 530,647 2022 Notes 670,000 668,906 670,857 670,000 668,849 684,043 2025 Notes 500,000 492,120 487,240 500,000 491,885 500,885 2026 Notes 500,000 495,360 508,551 500,000 495,245 520,144 2028 Notes 400,000 394,285 401,807 — — — 2044 Notes 600,000 593,262 605,816 600,000 593,234 637,827 2048 Notes 700,000 686,508 698,234 — — — RCF — — — 370,000 370,000 370,000 Total long-term debt $ 4,220,000 $ 4,176,346 $ 4,244,116 $ 3,490,000 $ 3,464,712 $ 3,594,177 (1) Fair value is measured using the market approach and Level 2 inputs. Debt activity. The following table presents the debt activity of the Partnership for the three months ended March 31, 2018 : thousands Carrying Value Balance at December 31, 2017 $ 3,464,712 RCF borrowings 260,000 Issuance of 2028 Notes 400,000 Issuance of 2048 Notes 700,000 Repayments of RCF borrowings (630,000 ) Other (18,366 ) Balance at March 31, 2018 $ 4,176,346
Interest Expense Table	The following table summarizes the amounts included in interest expense: Three Months Ended thousands 2018 2017 Third parties Long-term debt $ (41,283 ) $ (34,619 ) Amortization of debt issuance costs and commitment fees (2,054 ) (1,630 ) Capitalized interest 4,054 816 Total interest expense – third parties (39,283 ) (35,433 ) Affiliates Deferred purchase price obligation – Anadarko (1) — (71 ) Total interest expense – affiliates — (71 ) Interest expense $ (39,283 ) $ (35,504 ) (1) See Note 3 for a discussion of the Deferred purchase price obligation - Anadarko.

Description of Business and B29

Description of Business and Basis of Presentation - Assets and Investments Table (Details)	Mar. 31, 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	1
[1]	Includes the DBM water systems.

Description of Business and B30

Description of Business and Basis of Presentation - Ownership Interests and Method of Consolidation Table (Details)	3 Months Ended
	Mar. 31, 2018
Chipeta [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Ownership interest by noncontrolling interest owner	25.00%
Equity Investments [Member] | Fort Union [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	14.81%	[1]
Equity Investments [Member] | White Cliffs [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	10.00%	[1]
Equity Investments [Member] | Rendezvous [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	22.00%	[1]
Equity Investments [Member] | Mont Belvieu JV [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	25.00%	[1]
Equity Investments [Member] | Texas Express Pipeline LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	20.00%	[1]
Equity Investments [Member] | Texas Express Gathering LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	20.00%	[1]
Equity Investments [Member] | Front Range Pipeline LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	33.33%	[1]
Proportionate Consolidation [Member] | Marcellus Interest Systems [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	33.75%	[2]
Proportionate Consolidation [Member] | Newcastle System [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	50.00%	[2]
Proportionate Consolidation [Member] | Springfield System [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	50.10%	[2]
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 the Partnership exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to the Partnership’s share of average throughput for these investments.
[2]	The Partnership proportionately consolidates its 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 interest in the consolidated financial statements.

Description of Business and B31

Description of Business and Basis of Presentation - Impact of New Accounting Pronouncement - Statement of Operations Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Revenues
Product sales		$ 75,937
Expenses
Cost of product	[1]	77,799	$ 189,359
Operation and maintenance	[1]	88,279	73,760
Depreciation and amortization		76,842	69,702
Income tax (benefit) expense		1,502	3,552
Net income attributable to noncontrolling interest		2,985	2,102
Net income (loss) attributable to Western Gas Partners, LP		149,363	$ 101,889
Fee Based [Member]
Revenues
Service revenues - fee and product based		338,419
Product Based [Member]
Revenues
Service revenues - fee and product based		22,593
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member]
Revenues
Product sales		292,291
Expenses
Cost of product		274,966
Operation and maintenance		88,139
Depreciation and amortization		76,153
Income tax (benefit) expense		1,509
Net income attributable to noncontrolling interest		2,498
Net income (loss) attributable to Western Gas Partners, LP		151,185
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Fee Based [Member]
Revenues
Service revenues - fee and product based		342,338
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Product Based [Member]
Revenues
Service revenues - fee and product based		0
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member]
Revenues
Product sales		(216,354)
Expenses
Cost of product		(197,167)
Operation and maintenance		140
Depreciation and amortization		689
Income tax (benefit) expense		(7)
Net income attributable to noncontrolling interest		487
Net income (loss) attributable to Western Gas Partners, LP		(1,822)
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member] | Fee Based [Member]
Revenues
Service revenues - fee and product based		(3,919)
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member] | Product Based [Member]
Revenues
Service revenues - fee and product based		$ 22,593
[1]	Cost of product includes product purchases from Anadarko (as defined in Note 1) of $20.2 million and $16.0 million for the three months ended March 31, 2018 and 2017, respectively. Operation and maintenance includes charges from Anadarko of $20.2 million and $17.1 million for the three months ended March 31, 2018 and 2017, respectively. General and administrative includes charges from Anadarko of $11.6 million and $9.5 million for the three months ended March 31, 2018 and 2017, respectively. See Note 6.

Description of Business and B32

Description of Business and Basis of Presentation - Impact of New Accounting Pronouncement - Balance Sheet Table (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Assets
Other current assets	[1]	$ 22,747	$ 14,816
Net property, plant and equipment		6,063,547	5,730,891
Other assets	[2]	14,525	11,757
Liabilities
Accrued liabilities	[3]	78,798	47,899
Deferred income taxes		8,592	7,409
Other liabilities	[4]	128,757	3,491
Equity and partners' capital
Total equity and partners' capital		3,874,848	$ 3,971,011
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member]
Assets
Other current assets		16,909
Net property, plant and equipment		5,977,144
Other assets		14,303
Liabilities
Accrued liabilities		74,090
Deferred income taxes		8,746
Other liabilities		2,553
Equity and partners' capital
Total equity and partners' capital		3,913,143
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member]
Assets
Other current assets		5,838
Net property, plant and equipment		86,403
Other assets		222
Liabilities
Accrued liabilities		4,708
Deferred income taxes		(154)
Other liabilities		126,204
Equity and partners' capital
Total equity and partners' capital		$ (38,295)
[1]	Other current assets includes affiliate amounts of $5.7 million and zero as of March 31, 2018, and December 31, 2017, respectively.
[2]	Other assets includes affiliate amounts of $0.2 million and zero as of March 31, 2018, and December 31, 2017, respectively.
[3]	Accrued liabilities includes affiliate amounts of $2.1 million and $0.2 million as of March 31, 2018, and December 31, 2017, respectively.
[4]	Other liabilities includes affiliate amounts of $42.4 million and $0.7 million as of March 31, 2018, and December 31, 2017, respectively.

Description of Business and B33

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018
Loss on divestiture and other, net	[1],[2]	$ (116)	$ (119,487)
Proceeds from property insurance claims		0	24,000
Cumulative effect of accounting change	[3]	$ (44,409)
Contract term
Minimum [Member]
Contract term		5 years
Maximum [Member]
Contract term		10 years
Delaware Basin Midstream Complex [Member]
Loss on divestiture and other, net			5,700
Proceeds from insurance claims, total			29,800
Proceeds from business interruption insurance claims			5,767
Proceeds from property insurance claims			$ 24,000
Accounting Standards Update 2014-09 [Member]
Cumulative effect of accounting change				$ (44,409)
[1]	Includes losses related to an incident at the DBM complex for the three months ended March 31, 2017. See Note 1.
[2]	Includes losses related to an incident at the DBM complex for the three months ended March 31, 2017. See Note 1.
[3]	See Note 1.

Revenue from Contracts with C34

Revenue from Contracts with Customers - Revenue From Contracts With Customers Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Product sales	$ 75,937
Total revenues and other	437,168	$ 516,193
Fee Based [Member]
Disaggregation of Revenue [Line Items]
Service revenues - fee and product based	338,419
Product Based [Member]
Disaggregation of Revenue [Line Items]
Service revenues - fee and product based	22,593
Customers [Member]
Disaggregation of Revenue [Line Items]
Product sales	77,180
Total revenue from customers	438,192
Customers [Member] | Fee Based [Member]
Disaggregation of Revenue [Line Items]
Service revenues - fee and product based	338,419
Customers [Member] | Product Based [Member]
Disaggregation of Revenue [Line Items]
Service revenues - fee and product based	22,593
Other Than Customers [Member]
Disaggregation of Revenue [Line Items]
Net gains (losses) on commodity price swap agreements	(1,243)
Other	$ 219

Revenue from Contracts with C35

Revenue from Contracts with Customers - Contract Assets Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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	(2,494)
Additional estimated revenues recognized	3,425
Balance at March 31, 2018	6,060
Contract assets at March 31, 2018
Other current assets		$ 5,838	$ 0
Other assets		222
Total contract assets from contracts with customers	$ 0	$ 6,060	$ 0

Revenue from Contracts with C36

Revenue from Contracts with Customers - Contract Liabilities Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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	28,538
Revenues recognized during the period that were included in the adoption effect	(1,027)
Balance at March 31, 2018	148,228
Contract liabilities at March 31, 2018
Accrued liabilities		$ 22,024	$ 0
Other liabilities		126,204
Total contract liabilities from contracts with customers	$ 0	$ 148,228	$ 0

Revenue from Contracts with C37

Revenue from Contracts with Customers - Expected Revenues Table (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied, expected timing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 267,905
Performance obligation expected to be satisfied, expected timing	9 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	$ 440,723
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	$ 496,050
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	$ 469,728
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	$ 1,697,687
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 3,833,085

Revenue from Contracts with C38

Revenue from Contracts with Customers - Additional Information (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Revenue from Contracts with Customer [Line Items]
Accounts receivable, net	[1]	$ 189,074	$ 160,432
Customers [Member]
Revenue from Contracts with Customer [Line Items]
Accounts receivable, net		$ 252,300	$ 244,400
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $56.3 million and $36.3 million as of March 31, 2018, and December 31, 2017, respectively.

Acquisitions and Divestitures -

Acquisitions and Divestitures - Additional Information (Details) - USD ($) $ in Thousands	Mar. 17, 2017	Mar. 31, 2017	Jun. 30, 2017
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
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
Non-Operated Marcellus Interest [Member]
Property, Plant and Equipment [Line Items]
Percentage ownership interest	33.75%

Partnership Distributions - Cas

Partnership Distributions - Cash Distributions Table (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	[1]	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Distributions Made to Members or Limited Partners [Abstract]
Total quarterly distribution per unit	$ 0.935		$ 0.920	$ 0.905	$ 0.890	$ 0.875
Total quarterly cash distribution	$ 221,133		$ 216,586	$ 212,038	$ 207,491	$ 188,753
[1]	The Board of Directors declared a cash distribution to the Partnership’s unitholders for the first quarter of 2018 of $0.935 per unit, or $221.1 million in aggregate, including incentive distributions, but excluding distributions on Class C units (see Class C unit distributions below). The cash distribution is payable on May 14, 2018, to unitholders of record at the close of business on May 2, 2018.

Partnership Distributions - Add

Partnership Distributions - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	May 02, 2017	Mar. 01, 2017	Mar. 31, 2018	Mar. 31, 2017
Distribution Made to Limited Partner [Line Items]
Partnership agreement day requirement of distribution of available cash			45 days
Incentive distributions percentage			48.00%
Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Distribution sharing percentage			1.50%
Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Distribution sharing percentage			49.50%
Class C Units [Member]
Distribution Made to Limited Partner [Line Items]
Discount rate percentage			6.00%
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
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
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)	3 Months Ended
	Mar. 31, 2018shares
Change In Units [Roll Forward]
Balance	168,429,056
Units issued	261,394
Balance	168,690,450
Common Units [Member]
Change In Units [Roll Forward]
Balance	152,602,105
Balance	152,602,105
Class C Units [Member]
Change In Units [Roll Forward]
Balance	13,243,883
Units issued	261,394
Balance	13,505,277
General Partner [Member]
Change In Units [Roll Forward]
Balance	2,583,068
Balance	2,583,068

Equity and Partners' Capital 43

Equity and Partners' Capital - Calculation of Net Income (Loss) Per Unit Table (Details) - USD ($) $ / shares in Units, $ in Thousands		May 02, 2017	Mar. 01, 2017	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Unit [Line Items]
Net income (loss) attributable to Western Gas Partners, LP				$ 149,363	$ 101,889
General partner interest in net (income) loss	[1]			(83,439)	(68,162)
Series A Preferred Units [Member]
Earnings Per Unit [Line Items]
Limited partners’ interest in net income (loss)	[2]			$ 0	$ 28,174
Anti-dilutive units excluded from computation of earnings per unit	[3]			0	18,147,000
Series A Preferred Units [Member] | Series A Preferred Units March 2017 Conversion [Member]
Earnings Per Unit [Line Items]
Series A Preferred units, percentage converted			50.00%
Series A Preferred units, common units issued upon conversion			1
Series A Preferred Units [Member] | Series A Preferred Units May 2017 Conversion [Member]
Earnings Per Unit [Line Items]
Series A Preferred units, percentage converted		50.00%
Series A Preferred units, common units issued upon conversion		1
Common and Class C Units [Member]
Earnings Per Unit [Line Items]
Limited partners’ interest in net income (loss)	[1]			$ 65,924	$ 5,553
Common Units [Member]
Earnings Per Unit [Line Items]
Limited partners’ interest in net income (loss)	[2]			$ 58,323	$ 1,714
Net income (loss) per common unit – basic and diluted	[4]			$ 0.38	$ 0.01
Weighted-average units outstanding - basic and diluted				152,602,000	134,448,000
Class C Units [Member]
Earnings Per Unit [Line Items]
Limited partners’ interest in net income (loss)	[2]			$ 7,601	$ 3,839
Anti-dilutive units excluded from computation of earnings per unit	[3]			13,380,000	12,452,000
[1]	Represents net income (loss) earned on and subsequent to the date of acquisition of the Partnership assets (as defined in Note 1). See Note 5.
[2]	Adjusted to reflect amortization of the beneficial conversion features.
[3]	The impact of Class C units would be anti-dilutive for all periods presented and the conversion of Series A Preferred units would be anti-dilutive for the three months ended March 31, 2017. On March 1, 2017, 50% of the outstanding Series A Preferred units converted into common units on a one-for-one basis, and on May 2, 2017, all remaining Series A Preferred units converted into common units on a one-for-one basis.
[4]	See Note 5 for the calculation of net income (loss) per common unit.

Equity and Partners' Capital 44

Equity and Partners' Capital - Additional Information (Details) - USD ($) $ in Thousands	May 02, 2017	Mar. 01, 2017	Nov. 30, 2014	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2017	Jul. 31, 2017
Schedule Of Investments [Line Items]
Units issued				261,394
Series A Preferred units, amortization of beneficial conversion feature				$ 0
General partner units owned				2,583,068				2,583,068
Western Gas Partners, LP [Member] | Western Gas Equity Partners, LP [Member]
Schedule Of Investments [Line Items]
General partner units owned				2,583,068
General partner's interest				1.50%
Class C Units [Member]
Schedule Of Investments [Line Items]
Units issued				261,394
Class C units, common units issued upon conversion				1
Beneficial conversion feature							$ 34,800
Limited partner units owned				13,505,277				13,243,883
Class C Units [Member] | Western Gas Partners, LP [Member] | Other Subsidiaries of Anadarko [Member]
Schedule Of Investments [Line Items]
Limited partner units owned				13,505,277
Class C Units [Member] | Other Subsidiaries of Anadarko [Member]
Schedule Of Investments [Line Items]
Units issued			10,913,853
Series A Preferred Units [Member]
Schedule Of Investments [Line Items]
Series A Preferred units, amortization of beneficial conversion feature					$ 48,100
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
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
Series A Preferred Units [Member] | Private Investor [Member]
Schedule Of Investments [Line Items]
Units issued						21,922,831
Common Units [Member]
Schedule Of Investments [Line Items]
Limited partner units owned				152,602,105				152,602,105
Common Units [Member] | Western Gas Partners, LP [Member] | Public [Member]
Schedule Of Investments [Line Items]
Limited partner units owned				100,458,679
Limited partner ownership interest				59.60%
Common Units [Member] | Western Gas Partners, LP [Member] | Western Gas Equity Partners, LP [Member]
Schedule Of Investments [Line Items]
Limited partner units owned				50,132,046
Limited partner ownership interest				29.70%
Common Units [Member] | Western Gas Partners, LP [Member] | Other Subsidiaries of Anadarko [Member]
Schedule Of Investments [Line Items]
Limited partner units owned				2,011,380
Incentive Distribution Rights [Member] | Western Gas Partners, LP [Member] | Western Gas Equity Partners, LP [Member]
Schedule Of Investments [Line Items]
General partner's interest				100.00%
Common and Class C Units [Member] | Western Gas Partners, LP [Member] | Other Subsidiaries of Anadarko [Member]
Schedule Of Investments [Line Items]
Limited partner ownership interest				9.20%
July 2017 COP [Member]
Schedule Of Investments [Line Items]
Maximum aggregate principal of common units									$ 500,000

Transactions with Affiliates -

Transactions with Affiliates - Commodity Price Swap Agreements Tables (Details)		Mar. 31, 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 46

Transactions with Affiliates - Summary of Affiliate Transactions Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Related Party Transaction [Line Items]
Revenues and other		$ 437,168	$ 516,193
Equity income, net – affiliates	[1]	20,424	19,461
Cost of product	[2]	77,799	189,359
Operation and maintenance	[2]	88,279	73,760
General and administrative	[2]	14,132	12,659
Operating expenses		269,582	522,516
Interest income	[3]	4,225	4,225
Interest expense	[4]	39,283	35,504
Distributions to unitholders	[5]	216,586	185,565
Above-market component of swap agreements with Anadarko	[5]	14,282	12,297
Affiliates [Member]
Related Party Transaction [Line Items]
Revenues and other	[1]	241,062	315,155
Cost of product	[1]	20,244	15,988
Operation and maintenance	[6]	20,248	17,089
General and administrative	[7]	11,614	9,535
Operating expenses		52,106	42,612
Interest expense	[8]	0	71
Distributions to unitholders	[9]	$ 124,164	$ 103,123
[1]	Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, recognized under gathering, treating or processing agreements, and purchase and sale agreements.
[2]	Cost of product includes product purchases from Anadarko (as defined in Note 1) of $20.2 million and $16.0 million for the three months ended March 31, 2018 and 2017, respectively. Operation and maintenance includes charges from Anadarko of $20.2 million and $17.1 million for the three months ended March 31, 2018 and 2017, respectively. General and administrative includes charges from Anadarko of $11.6 million and $9.5 million for the three months ended March 31, 2018 and 2017, respectively. See Note 6.
[3]	Represents interest income recognized on the note receivable from Anadarko.
[4]	Includes affiliate (as defined in Note 1) amounts of zero and $(0.1) million for the three months ended March 31, 2018 and 2017, respectively. See Note 10.
[5]	See Note 6.
[6]	Represents expenses incurred on and subsequent to the date of the acquisition of Partnership assets, as well as expenses incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets.
[7]	Represents general and administrative expense incurred on and subsequent to the date of the acquisition of Partnership assets, as well as a management services fee for reimbursement of expenses incurred by Anadarko for periods prior to the acquisition of the Partnership assets by the Partnership. These amounts include equity-based compensation expense allocated to the Partnership by Anadarko (see WES LTIP and Anadarko Incentive Plan within this Note 6).
[8]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).
[9]	Represents distributions paid under the partnership agreement (see Note 4 and Note 5).

Transactions with Affiliates 47

Transactions with Affiliates - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended
		May 31, 2008	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Note receivable - Anadarko			$ 260,000,000		$ 260,000,000
Above-market component of swap agreements with Anadarko	[1]		14,282,000
Contributions of equity-based compensation from Anadarko			1,464,000
Anadarko Incentive Plan [Member]
Related Party Transaction [Line Items]
Equity-based compensation expense			2,100,000	$ 1,200,000
Contributions of equity-based compensation from Anadarko			$ 1,464,000
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
Natural Gas [Member] | Gathering, Treating, Transportation and Disposal [Member]
Related Party Transaction [Line Items]
Affiliate throughput percent			36.00%	32.00%
Natural Gas [Member] | Processing [Member]
Related Party Transaction [Line Items]
Affiliate throughput percent			36.00%	49.00%
Crude Oil, NGL and Produced Water [Member] | Gathering, Treating, Transportation and Disposal [Member]
Related Party Transaction [Line Items]
Affiliate throughput percent			63.00%	54.00%
Affiliates [Member]
Related Party Transaction [Line Items]
Note receivable - Anadarko		$ 260,000,000
Note receivable, due date		May 14, 2038
Fixed annual rate for note receivable bearing interest		6.50%
Net gains (losses) on commodity price swap agreements			$ (1,243,000)	$ (500,000)
Affiliates [Member] | Level 2 Inputs [Member] | Market Approach Valuation Technique [Member]
Related Party Transaction [Line Items]
Fair value of the note receivable			$ 316,200,000		$ 325,200,000
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	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 8,272,083	$ 7,871,102
Accumulated depreciation	2,208,536	2,140,211
Net property, plant and equipment	6,063,547	5,730,891
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	4,449	4,450
Gathering Systems and Processing Complexes [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 7,305,279	7,114,701
Gathering Systems and Processing Complexes [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Gathering Systems and Processing Complexes [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	47 years
Pipelines and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 137,765	137,644
Pipelines and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Pipelines and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Assets Under Construction [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 794,012	577,914
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 30,578	$ 36,393
Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years

Property, Plant and Equipment49

Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Impairments	$ 148	$ 164,742	$ 178,400
Fort Union [Member]
Property, Plant and Equipment [Line Items]
Equity investment impairment loss			3,110
Granger Complex [Member]
Property, Plant and Equipment [Line Items]
Impairments			158,800
Granger Complex [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Income Approach Valuation Technique [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value			48,500
Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments			19,600
Hilight System [Member]
Property, Plant and Equipment [Line Items]
Impairments			8,200
Granger Straddle Plant [Member]
Property, Plant and Equipment [Line Items]
Impairments			3,700
Granger Straddle Plant [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Income Approach Valuation Technique [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value			600
Northeast Wyoming Facility [Member]
Property, Plant and Equipment [Line Items]
Impairments			2,000
Northeast Wyoming Facility [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Market Approach Valuation Technique [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value			$ 400

Equity Investments - Equity Inv

Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Schedule of Equity Method Investments [Line Items]
Balance		$ 566,211
Investment earnings (loss), net of amortization	[1]	20,424		$ 19,461
Distributions		(20,941)		(19,114)
Distributions in excess of cumulative earnings		(8,013)	[2]	$ (3,453)
Balance		557,681
Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance		7,030
Investment earnings (loss), net of amortization		144
Distributions		(144)
Distributions in excess of cumulative earnings	[2]	(741)
Balance		6,289
White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance		44,945
Investment earnings (loss), net of amortization		2,673
Distributions		(2,527)
Distributions in excess of cumulative earnings	[2]	(1,228)
Balance		43,863
Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance		42,528
Investment earnings (loss), net of amortization		225
Distributions		(710)
Distributions in excess of cumulative earnings	[2]	(1,162)
Balance		40,881
Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance		110,299
Investment earnings (loss), net of amortization		7,090
Distributions		(7,100)
Distributions in excess of cumulative earnings	[2]	(1,325)
Balance		108,964
Texas Express Gathering LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance		15,879
Investment earnings (loss), net of amortization		1,066
Distributions		(1,127)
Distributions in excess of cumulative earnings	[2]	(20)
Balance		15,798
Texas Express Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance		178,975
Investment earnings (loss), net of amortization		4,417
Distributions		(4,480)
Distributions in excess of cumulative earnings	[2]	(2,168)
Balance		176,744
Front Range Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance		166,555
Investment earnings (loss), net of amortization		4,809
Distributions		(4,853)
Distributions in excess of cumulative earnings	[2]	(1,369)
Balance		$ 165,142
[1]	Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets, 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		Mar. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables, net		$ 188,550	$ 160,387
Other receivables, net		524	45
Total accounts receivable, net	[1]	$ 189,074	$ 160,432
[1]	Accounts receivable, net includes amounts receivable from affiliates (as defined in Note 1) of $56.3 million and $36.3 million as of March 31, 2018, and December 31, 2017, respectively.

Components of Working Capital52

Components of Working Capital - Other Current Assets Table (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Other Current Assets [Line Items]
Natural gas liquids inventory		$ 9,275	$ 10,788
Imbalance receivables		6,293	1,640
Prepaid insurance		1,341	2,388
Contract assets		5,838	0
Total other current assets	[1]	$ 22,747	$ 14,816
[1]	Other current assets includes affiliate amounts of $5.7 million and zero as of March 31, 2018, and December 31, 2017, respectively.

Components of Working Capital53

Components of Working Capital - Accrued Liabilities Table (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Components Of Working Capital [Abstract]
Accrued interest expense		$ 50,022	$ 40,632
Short-term asset retirement obligations		1,339	2,304
Short-term remediation and reclamation obligations		833	833
Income taxes payable		2,666	2,495
Contract liabilities		22,024	0
Other accrued liabilities		1,914	1,635
Total accrued liabilities	[1]	$ 78,798	$ 47,899
[1]	Accrued liabilities includes affiliate amounts of $2.1 million and $0.2 million as of March 31, 2018, and December 31, 2017, respectively.

Debt and Interest Expense - Deb

Debt and Interest Expense - Debt Outstanding Table (Details) - USD ($)		Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total long-term debt, principal		$ 4,220,000,000	$ 3,490,000,000
Carrying value		4,176,346,000	3,464,712,000
Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	4,244,116,000	3,594,177,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal		0	370,000,000
Carrying value		0	370,000,000
Revolving Credit Facility [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	0	370,000,000
Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Principal		350,000,000	350,000,000
Carrying value		349,810,000	349,684,000
Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	349,542,000	350,631,000
Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Principal		500,000,000	500,000,000
Carrying value		496,095,000	495,815,000
Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	522,069,000	530,647,000
Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Principal		670,000,000	670,000,000
Carrying value		668,906,000	668,849,000
Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	670,857,000	684,043,000
Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Principal		500,000,000	500,000,000
Carrying value		492,120,000	491,885,000
Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	487,240,000	500,885,000
Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Principal		500,000,000	500,000,000
Carrying value		495,360,000	495,245,000
Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	508,551,000	520,144,000
Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Principal		400,000,000	0
Carrying value		394,285,000	0
Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	401,807,000	0
Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Principal		600,000,000	600,000,000
Carrying value		593,262,000	593,234,000
Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	605,816,000	637,827,000
Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member]
Debt Instrument [Line Items]
Principal		700,000,000	0
Carrying value		686,508,000	0
Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	[1]	$ 698,234,000	$ 0
[1]	Fair value is measured using the market approach and Level 2 inputs.

Debt and Interest Expense - D55

Debt and Interest Expense - Debt Activity Table (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Changes in Debt Outstanding [Roll Forward]
Beginning balance	$ 3,464,712
Other	(18,366)
Ending balance	4,176,346
Revolving Credit Facility [Member]
Changes in Debt Outstanding [Roll Forward]
Beginning balance	370,000
RCF borrowings	260,000
Repayments of RCF borrowings	(630,000)
Ending balance	0
4.500% Senior Notes due 2028 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Beginning balance	0
Issuance of senior notes	400,000
Ending balance	394,285
5.300% Senior Notes due 2048 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Beginning balance	0
Issuance of senior notes	700,000
Ending balance	$ 686,508

Debt and Interest Expense - Int

Debt and Interest Expense - Interest Expense Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Debt Instrument [Line Items]
Interest expense	[1]	$ (39,283)	$ (35,504)
Third Parties [Member]
Debt Instrument [Line Items]
Long-term debt		(41,283)	(34,619)
Amortization of debt issuance costs and commitment fees		(2,054)	(1,630)
Capitalized interest		4,054	816
Interest expense		(39,283)	(35,433)
Affiliates [Member]
Debt Instrument [Line Items]
Interest expense	[2]	0	(71)
Affiliates [Member] | Deferred Purchase Price Obligation - Anadarko [Member]
Debt Instrument [Line Items]
Deferred purchase price obligation - Anadarko	[3]	$ 0	$ (71)
[1]	Includes affiliate (as defined in Note 1) amounts of zero and $(0.1) million for the three months ended March 31, 2018 and 2017, respectively. See Note 10.
[2]	Includes amounts related to the Deferred purchase price obligation - Anadarko (see Note 3 and Note 10).
[3]	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	Mar. 31, 2018	Mar. 31, 2017	Feb. 25, 2014
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility, maximum borrowing capacity	$ 1,500,000,000			$ 1,200,000,000
Facility, expandable maximum borrowing capacity	$ 2,000,000,000
Facility, expiration date	Feb. 15, 2023
Facility, fee rate		0.20%	0.20%
Facility, outstanding borrowings		$ 0
Outstanding letters of credit		4,600,000
Facility, available borrowing capacity		$ 1,495,400,000
Facility, interest rate at period end		3.18%	2.28%
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Facility, fee rate		0.125%
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Facility, fee rate		0.25%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable margin added		1.00%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable margin added		1.50%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Alternate Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin added		1.00%
Revolving Credit Facility [Member] | Percentage Above Federal Funds Effective Rate [Member] | Alternate Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin added		0.50%
Revolving Credit Facility [Member] | Base Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable margin added		0.00%
Revolving Credit Facility [Member] | Base Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable margin added		0.50%
Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Fixed interest rate		2.60%
Debt instrument, maturity date		Aug. 15, 2018
Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Fixed interest rate		5.375%
Debt instrument, maturity date		Jun. 1, 2021
Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Fixed interest rate		4.00%
Debt instrument, maturity date		Jul. 1, 2022
Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Fixed interest rate		3.95%
Debt instrument, maturity date		Jun. 1, 2025
Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Fixed interest rate		4.65%
Debt instrument, maturity date		Jul. 1, 2026
Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Fixed interest rate		4.50%
Debt instrument, maturity date		Mar. 1, 2028
Offering percent		99.435%
Effective interest rate		4.682%
Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Fixed interest rate		5.45%
Debt instrument, maturity date		Apr. 1, 2044
Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member]
Debt Instrument [Line Items]
Fixed interest rate		5.30%
Debt instrument, maturity date		Mar. 1, 2048
Offering percent		99.169%
Effective interest rate		5.431%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 17, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Loss Contingencies [Line Items]
Contract liabilities		$ 22,024		$ 0
Rent expense associated with office and equipment leases		13,800	$ 8,600
DBJV Arbitration [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Gathering fees sought in arbitration		194,200
Fees sought in counterclaim		$ 14,900
Percentage recovery from third party		50.00%
Percentage due to third party		50.00%
Contract liabilities		$ 7,500
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%