Western Midstream Partners (WES) 10-Q 5 May 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity Registrant Name	WESTERN MIDSTREAM PARTNERS, LP
Entity File Number	001-35753
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-0967367
Entity Address, Address Line One	9950 Woodloch Forest Drive
Entity Address, City or Town	The Woodlands,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77380
City Area Code	(832)
Local Phone Number	636-1009
Title of 12(b) Security	Common units
Trading Symbol	WES
Security Exchange Name	NYSE
Entity Common Units Outstanding		443,971,409
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001423902
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Former Address [Member]
Entity Information [Line Items]
Entity Address, Address Line One	1201 Lake Robbins Drive
Entity Address, City or Town	The Woodlands,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77380
WES Operating [Member]
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity Registrant Name	WESTERN MIDSTREAM OPERATING, LP
Entity File Number	001-34046
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-1075808
Entity Address, Address Line One	9950 Woodloch Forest Drive
Entity Address, City or Town	The Woodlands,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77380
City Area Code	(832)
Local Phone Number	636-1009
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001414475
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
WES Operating [Member] | Former Address [Member]
Entity Information [Line Items]
Entity Address, Address Line One	1201 Lake Robbins Drive
Entity Address, City or Town	The Woodlands,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77380

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Revenues and Other
Revenues and other		$ 774,313	$ 671,883
Equity income, net – related parties		61,347	57,992
Operating expenses
Cost of product	[1]	103,270	114,063
Operation and maintenance	[1]	159,191	142,829
General and administrative	[1]	40,465	22,844
Property and other taxes		18,476	16,285
Depreciation and amortization		132,319	113,946
Long-lived asset impairments		155,785	390
Goodwill impairment		441,017	0
Total operating expenses		1,050,523	410,357
Gain (loss) on divestiture and other, net		(40)	(590)
Operating income (loss)		(214,903)	318,928
Interest income – related parties		4,225	4,225
Interest expense		(88,586)	(65,876)
Gain (loss) on early extinguishment of debt		7,345	0
Other income (expense), net	[2]	(1,761)	(35,206)
Income (loss) before income taxes		(293,680)	222,071
Income tax expense (benefit)		(4,280)	10,092
Net income (loss)		(289,400)	211,979
Net income (loss) attributable to noncontrolling interests		(32,873)	93,319
Net income (loss) attributable to Western Midstream Partners, LP		(256,527)	118,660
Limited partners' interest in net income (loss):
Net income (loss) attributable to Western Midstream Partners, LP		(256,527)	118,660
Pre-acquisition net (income) loss allocated to Anadarko		0	(29,116)
General partner interest in net (income) loss		5,131	0
Limited partners' interest in net income (loss)	[3]	(251,396)	89,544
Affiliates [Member]
Revenues and Other
Revenues and other		482,385	378,437
Operating expenses
Cost of product		77,903	56,172
Operation and maintenance		32,841	39,141
General and administrative		21,855	18,894
Total operating expenses		132,599	114,207
Interest expense		(43)	(1,833)
Affiliates [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		447,783	326,642
Affiliates [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		2,978	1,352
Affiliates [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		31,624	50,443
Third Parties [Member]
Revenues and Other
Revenues and other		291,928	293,446
Operating expenses
Interest expense		(88,543)	(64,043)
Third Parties [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		253,613	253,332
Third Parties [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		12,943	18,027
Third Parties [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		25,025	21,690
Third Parties [Member] | Other [Member]
Revenues and Other
Revenues and other		$ 347	$ 397
Limited Partner [Member]
Limited partners' interest in net income (loss):
Net income (loss) per common unit - basic and diluted	[3]	$ (0.57)	$ 0.30
Weighted-average common units outstanding - basic and diluted		443,971	299,556
[1]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.9 million and $18.9 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .
[2]	Includes losses associated with the interest-rate swap agreements for the three months ended March 31, 2019 . See Note 11 .
[3]	See Note 5 .

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Cost of product	[1]	$ 103,270	$ 114,063
Operation and maintenance	[1]	159,191	142,829
General and administrative	[1]	40,465	22,844
Affiliates [Member]
Cost of product		77,903	56,172
Operation and maintenance		32,841	39,141
General and administrative		$ 21,855	$ 18,894
[1]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.9 million and $18.9 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents		$ 152,282	$ 99,962
Accounts receivable, net	[1]	257,239	260,512
Other current assets	[2]	81,027	41,938
Total current assets		490,548	402,412
Property, plant, and equipment
Cost		12,545,357	12,355,671
Less accumulated depreciation		3,558,626	3,290,740
Net property, plant, and equipment		8,986,731	9,064,931
Goodwill		4,783	445,800
Other intangible assets		800,482	809,391
Equity investments		1,292,104	1,285,717
Other assets	[3]	76,465	78,202
Total assets		11,908,998	12,346,453
Current liabilities
Accounts and imbalance payables		219,628	293,128
Short-term debt	[4]	11,184	7,873
Accrued ad valorem taxes		52,175	35,160
Accrued liabilities	[5]	166,738	149,793
Total current liabilities		449,725	485,954
Long-term liabilities
Long-term debt		8,088,761	7,951,565
Deferred income taxes		16,731	18,899
Asset retirement obligations		339,454	336,396
Other liabilities	[6]	222,042	208,346
Total long-term liabilities		8,666,988	8,515,206
Total liabilities		9,116,713	9,001,160
Equity and partners' capital
Common units (443,971,409 units issued and outstanding at March 31, 2020, and December 31, 2019)		2,684,136	3,209,947
General partner units (9,060,641 units issued and outstanding at March 31, 2020, and December 31, 2019)	[7]	(24,990)	(14,224)
Total partners' capital		2,659,146	3,195,723
Noncontrolling interests		133,139	149,570
Total equity and partners' capital		2,792,285	3,345,293
Total liabilities, equity, and partners' capital		11,908,998	12,346,453
Affiliates [Member]
Current assets
Accounts receivable, net		124,900	113,300
Other current assets		9,000	5,000
Note receivable - Anadarko	[8]	257,885	260,000
Property, plant, and equipment
Other assets		59,700	60,200
Current liabilities
Accrued liabilities		2,500	3,100
Long-term liabilities
Other liabilities		$ 107,800	$ 97,800
[1]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $124.9 million and $113.3 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019
[3]	Other assets includes related-party amounts of $59.7 million and $60.2 million as of March 31, 2020 , and December 31, 2019 , respectively. Other assets also includes $2.0 million and $4.5 million of NGLs line fill as of March 31, 2020 , and December 31, 2019 , respectively.
[4]	Short-term debt includes related-party amounts for finance leases of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively.
[5]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[6]	Other liabilities includes related-party amounts of $107.8 million and $97.8 million as of March 31, 2020 , and December 31, 2019 , respectively.
[7]	See Note 1 .
[8]	Note receivable – Anadarko is presented net of a $2.1 million allowance for expected credit losses as of March 31, 2020 . See Note 1 .

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Common units issued		443,971,409	443,971,409
Common units outstanding		443,971,409	443,971,409
General partner units issued		9,060,641	9,060,641
General partner units outstanding		9,060,641	9,060,641
Accounts receivable, net	[1]	$ 257,239	$ 260,512
Other current assets	[2]	81,027	41,938
Other assets	[3]	76,465	78,202
Accrued liabilities	[4]	166,738	149,793
Other liabilities	[5]	222,042	208,346
Natural-Gas Liquids [Member]
NGLs line fill inventory		2,000	4,500
Affiliates [Member]
Accounts receivable, net		124,900	113,300
Other current assets		9,000	5,000
Allowance for expected credit loss		2,100
Other assets		59,700	60,200
Finance leases - Short-term debt		2,600	7,900
Accrued liabilities		2,500	3,100
Other liabilities		$ 107,800	$ 97,800
[1]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $124.9 million and $113.3 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019
[3]	Other assets includes related-party amounts of $59.7 million and $60.2 million as of March 31, 2020 , and December 31, 2019 , respectively. Other assets also includes $2.0 million and $4.5 million of NGLs line fill as of March 31, 2020 , and December 31, 2019 , respectively.
[4]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[5]	Other liabilities includes related-party amounts of $107.8 million and $97.8 million as of March 31, 2020 , and December 31, 2019 , respectively.

Consolidated Statements of Equi

Consolidated Statements of Equity and Partners' Capital - USD ($) $ in Thousands		Total	Chipeta [Member]	WES Operating [Member]	Net Investment by Anadarko [Member]	Common Units [Member]	General Partner [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member]Chipeta [Member]	Noncontrolling Interests [Member]WES Operating [Member]
Balance at Dec. 31, 2018		$ 4,892,683			$ 1,388,018	$ 951,888		$ 2,552,777
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		211,979			29,116	89,544		93,319
Distributions to noncontrolling interest owners			$ (1,935)	$ (100,999)					$ (1,935)	$ (100,999)
Distributions to Partnership unitholders		(131,910)				(131,910)
Acquisitions from related parties	[1]	(2,007,501)			(2,141,827)	106,856		27,470
Contributions of equity-based compensation from Anadarko/Occidental		1,840				1,840
Net preacquisition contributions from (distributions to) related parties		451,591			451,591
Cumulative impact of the Merger transactions	[2]	0				3,169,800		(3,169,800)
Above-market component of swap agreements with Anadarko	[3]	7,407				7,407
WES Operating equity transactions, net	[4]	0				(752,796)		752,796
Adjustments of net deferred tax liabilities		268,727			273,102	(4,375)
Other		(341)				(332)		(9)
Balance at Mar. 31, 2019		3,591,541			$ 0	3,437,922		153,619
Balance at Dec. 31, 2019		3,345,293				3,209,947	$ (14,224)	149,570
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)		(289,400)				(251,396)	(5,131)	(32,873)
Distributions to noncontrolling interest owners			$ (1,738)	$ (5,807)					$ (1,738)	$ (5,807)
Distributions to Partnership unitholders		(281,786)				(276,151)	(5,635)
Acquisitions from related parties		0				(3,987)		3,987
Contributions of equity-based compensation from Anadarko/Occidental		4,105				4,105
Equity-based compensation expense		1,129				1,129
Net contributions from (distributions to) related parties	[5]	20,489				489		20,000
Balance at Mar. 31, 2020		$ 2,792,285				$ 2,684,136	$ (24,990)	$ 133,139
[1]	The amounts allocated to common unitholders and noncontrolling interests represent a non-cash investing activity related to the assets and liabilities assumed in the AMA acquisition.
[2]	See Note 1 .
[3]	See Note 6 .
[4]	For the three months ended March 31, 2019, the $752.8 million decrease to partners’ capital, together with net income (loss) attributable to Western Midstream Partners, LP, totaled $(634.1) million .
[5]	See December 2019 Agreements—Services, Secondment, and Employee Transfer Agreement within Note 1 .

Consolidated Statements of Eq_2

Consolidated Statements of Equity and Partners' Capital (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
WES Operating equity transactions, net	$ 0	[1]
Combined change in Partners' Capital from WES Operating equity transactions, net and net income (loss) attributable to Western Midstream Partners, LP	(634,100)
Common Units [Member]
WES Operating equity transactions, net	$ (752,796)	[1]
[1]	For the three months ended March 31, 2019, the $752.8 million decrease to partners’ capital, together with net income (loss) attributable to Western Midstream Partners, LP, totaled $(634.1) million .

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net income (loss)		$ (289,400)	$ 211,979
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		132,319	113,946
Long-lived asset impairments		155,785	390
Goodwill impairment		441,017	0
Non-cash equity-based compensation expense		5,234	2,368
Deferred income taxes		(2,168)	4,065
Accretion and amortization of long-term obligations, net		2,100	1,511
Equity income, net – related parties		(61,347)	(57,992)
Distributions from equity-investment earnings – related parties		60,868	54,221
(Gain) loss on divestiture and other, net		40	590
(Gain) loss on early extinguishment of debt		(7,345)	0
(Gain) loss on interest-rate swaps		0	35,638
Other		2,287	7
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		7,702	9,486
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		(28,924)	(55,529)
Change in other items, net		(24,857)	22,393
Net cash provided by operating activities		393,311	343,073
Cash flows from investing activities
Capital expenditures		(172,816)	(386,144)
Contributions to equity investments - related parties		(10,960)	(36,543)
Distributions from equity investments in excess of cumulative earnings – related parties		5,052	7,792
Proceeds from the sale of assets to third parties		0	(33)
Net cash used in investing activities		(178,724)	(2,515,732)
Cash flows from financing activities
Borrowings, net of debt issuance costs	[1]	3,586,173	2,430,750
Repayments of debt	[2]	(3,470,139)	(467,595)
Increase (decrease) in outstanding checks		(7,308)	(5,890)
Registration expenses related to the issuance of Partnership common units		0	(855)
Distributions to Partnership unitholders	[3]	(281,786)	(131,910)
Net contributions from (distributions to) related parties		20,489	451,591
Above-market component of swap agreements with Anadarko	[3]	0	7,407
Finance lease payments		(2,151)	0
Net cash provided by (used in) financing activities		(162,267)	2,180,564
Net increase (decrease) in cash and cash equivalents		52,320	7,905
Cash and cash equivalents at beginning of period		99,962	92,142
Cash and cash equivalents at end of period		152,282	100,047
Supplemental disclosures
Interest paid, net of capitalized interest		75,844	76,871
Taxes paid (reimbursements received)		(384)	96
Accrued capital expenditures		120,233	203,509
Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(1,738)	(1,935)
WES Operating [Member]
Cash flows from financing activities
Distributions to noncontrolling interest owners of WES Operating		(5,807)	(100,999)
Affiliates [Member]
Cash flows from investing activities
Acquisitions		0	(2,007,501)
Cash flows from financing activities
Borrowings, net of debt issuance costs			11,000
Repayments of debt			(439,600)
Distributions to Partnership unitholders		(150,609)	(102,654)
Affiliates [Member] | WES Operating [Member]
Cash flows from financing activities
Distributions to Partnership unitholders		(5,807)	(2,543)
Third Parties [Member]
Cash flows from investing activities
Acquisitions		$ 0	$ (93,303)
[1]	For the three months ended March 31, 2019 , includes an $11.0 million
[2]	For the three months ended March 31, 2019 , includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6 .
[3]	See Note 6 .

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Borrowings, net of debt issuance costs	[1]	$ 3,586,173	$ 2,430,750
Repayments of debt	[2]	$ 3,470,139	467,595
Affiliates [Member]
Borrowings, net of debt issuance costs			11,000
Repayments of debt			$ 439,600
[1]	For the three months ended March 31, 2019 , includes an $11.0 million
[2]	For the three months ended March 31, 2019 , includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6 .

Consolidated Statements of Op_3

Consolidated Statements of Operations - WES Operating - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Revenues and Other
Revenues and other		$ 774,313	$ 671,883
Equity income, net – related parties		61,347	57,992
Operating expenses
Cost of product	[1]	103,270	114,063
Operation and maintenance	[1]	159,191	142,829
General and administrative	[1]	40,465	22,844
Property and other taxes		18,476	16,285
Depreciation and amortization		132,319	113,946
Long-lived asset impairments		155,785	390
Goodwill impairment		441,017	0
Total operating expenses		1,050,523	410,357
Gain (loss) on divestiture and other, net		(40)	(590)
Operating income (loss)		(214,903)	318,928
Interest income – related parties		4,225	4,225
Interest expense		(88,586)	(65,876)
Gain (loss) on early extinguishment of debt		7,345	0
Other income (expense), net	[2]	(1,761)	(35,206)
Income (loss) before income taxes		(293,680)	222,071
Income tax expense (benefit)		(4,280)	10,092
Net income (loss)		(289,400)	211,979
Net income (loss) attributable to noncontrolling interest		(32,873)	93,319
Net income (loss) attributable to Western Midstream Operating, LP		(256,527)	118,660
Limited partners' interest in net income (loss):
Net income (loss) attributable to Western Midstream Operating, LP		(256,527)	118,660
Pre-acquisition net (income) loss allocated to Anadarko		0	(29,116)
Limited partners' interest in net income (loss)	[3]	(251,396)	89,544
Affiliates [Member]
Revenues and Other
Revenues and other		482,385	378,437
Operating expenses
Cost of product		77,903	56,172
Operation and maintenance		32,841	39,141
General and administrative		21,855	18,894
Total operating expenses		132,599	114,207
Interest expense		(43)	(1,833)
Affiliates [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		447,783	326,642
Affiliates [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		2,978	1,352
Affiliates [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		31,624	50,443
Third Parties [Member]
Revenues and Other
Revenues and other		291,928	293,446
Operating expenses
Interest expense		(88,543)	(64,043)
Third Parties [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		253,613	253,332
Third Parties [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		12,943	18,027
Third Parties [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		25,025	21,690
Third Parties [Member] | Other [Member]
Revenues and Other
Revenues and other		347	397
WES Operating [Member]
Revenues and Other
Revenues and other		774,313	671,883
Equity income, net – related parties		61,347	57,992
Operating expenses
Cost of product	[4]	103,270	114,063
Operation and maintenance	[4]	159,191	142,829
General and administrative	[4]	39,058	20,560
Property and other taxes		18,476	16,285
Depreciation and amortization		132,319	113,946
Long-lived asset impairments		155,785	390
Goodwill impairment		441,017	0
Total operating expenses		1,049,116	408,073
Gain (loss) on divestiture and other, net		(40)	(590)
Operating income (loss)		(213,496)	321,212
Interest income – related parties		4,225	4,225
Interest expense		(88,586)	(65,631)
Gain (loss) on early extinguishment of debt		7,345	0
Other income (expense), net	[2]	(1,763)	(35,264)
Income (loss) before income taxes		(292,275)	224,542
Income tax expense (benefit)		(4,280)	10,092
Net income (loss)		(287,995)	214,450
Net income (loss) attributable to noncontrolling interest		(27,665)	1,854
Net income (loss) attributable to Western Midstream Operating, LP		(260,330)	212,596
Limited partners' interest in net income (loss):
Net income (loss) attributable to Western Midstream Operating, LP		(260,330)	212,596
Pre-acquisition net (income) loss allocated to Anadarko		0	(29,116)
WES Operating [Member] | Common and Class C Units [Member]
Limited partners' interest in net income (loss):
Limited partners' interest in net income (loss)	[3]	(260,330)	183,480
WES Operating [Member] | Affiliates [Member]
Revenues and Other
Revenues and other		482,385	378,437
Operating expenses
Cost of product		77,900	56,200
Operation and maintenance		32,800	39,100
General and administrative		21,738	18,498
WES Operating [Member] | Affiliates [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		447,783	326,642
WES Operating [Member] | Affiliates [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		2,978	1,352
WES Operating [Member] | Affiliates [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		31,624	50,443
WES Operating [Member] | Third Parties [Member]
Revenues and Other
Revenues and other		291,928	293,446
WES Operating [Member] | Third Parties [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		253,613	253,332
WES Operating [Member] | Third Parties [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		12,943	18,027
WES Operating [Member] | Third Parties [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		25,025	21,690
WES Operating [Member] | Third Parties [Member] | Other [Member]
Revenues and Other
Revenues and other		$ 347	$ 397
[1]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.9 million and $18.9 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .
[2]	Includes losses associated with the interest-rate swap agreements for the three months ended March 31, 2019 . See Note 11 .
[3]	See Note 5 .
[4]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.7 million and $18.5 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .

Consolidated Statements of Op_4

Consolidated Statements of Operations - WES Operating (Parenthetical) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Cost of product	[1]	$ 103,270	$ 114,063
Operation and maintenance	[1]	159,191	142,829
General and administrative	[1]	40,465	22,844
Affiliates [Member]
Cost of product		77,903	56,172
Operation and maintenance		32,841	39,141
General and administrative		21,855	18,894
WES Operating [Member]
Cost of product	[2]	103,270	114,063
Operation and maintenance	[2]	159,191	142,829
General and administrative	[2]	39,058	20,560
WES Operating [Member] | Affiliates [Member]
Cost of product		77,900	56,200
Operation and maintenance		32,800	39,100
General and administrative		$ 21,738	$ 18,498
[1]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.9 million and $18.9 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .
[2]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.7 million and $18.5 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .

Consolidated Balance Sheets - W

Consolidated Balance Sheets - WES Operating - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents		$ 152,282	$ 99,962
Accounts receivable, net	[1]	257,239	260,512
Other current assets	[2]	81,027	41,938
Total current assets		490,548	402,412
Property, plant, and equipment
Cost		12,545,357	12,355,671
Less accumulated depreciation		3,558,626	3,290,740
Net property, plant, and equipment		8,986,731	9,064,931
Goodwill		4,783	445,800
Other intangible assets		800,482	809,391
Equity investments		1,292,104	1,285,717
Other assets	[3]	76,465	78,202
Total assets		11,908,998	12,346,453
Current liabilities
Accounts and imbalance payables		219,628	293,128
Short-term debt	[4]	11,184	7,873
Accrued ad valorem taxes		52,175	35,160
Accrued liabilities	[5]	166,738	149,793
Total current liabilities		449,725	485,954
Long-term liabilities
Long-term debt		8,088,761	7,951,565
Deferred income taxes		16,731	18,899
Asset retirement obligations		339,454	336,396
Other liabilities	[6]	222,042	208,346
Total long-term liabilities		8,666,988	8,515,206
Total liabilities		9,116,713	9,001,160
Equity and partners' capital
Common units (318,675,578 units issued and outstanding at March 31, 2020, and December 31, 2019)		2,684,136	3,209,947
Total partners' capital		2,659,146	3,195,723
Noncontrolling interest		133,139	149,570
Total equity and partners' capital		2,792,285	3,345,293
Total liabilities, equity, and partners' capital		11,908,998	12,346,453
WES Operating [Member]
Current assets
Cash and cash equivalents		148,760	98,122
Accounts receivable, net	[7]	249,843	260,748
Other current assets	[8]	79,324	39,914
Total current assets		477,927	398,784
Property, plant, and equipment
Cost		12,545,357	12,355,671
Less accumulated depreciation		3,558,626	3,290,740
Net property, plant, and equipment		8,986,731	9,064,931
Goodwill		4,783	445,800
Other intangible assets		800,482	809,391
Equity investments		1,292,104	1,285,717
Other assets	[9]	76,465	78,202
Total assets		11,896,377	12,342,825
Current liabilities
Accounts and imbalance payables		219,489	293,128
Short-term debt	[10]	11,184	7,873
Accrued ad valorem taxes		52,175	35,160
Accrued liabilities	[11]	160,175	149,639
Total current liabilities		443,023	485,800
Long-term liabilities
Long-term debt		8,088,761	7,951,565
Deferred income taxes		16,731	18,899
Asset retirement obligations		339,454	336,396
Other liabilities	[12]	222,042	208,346
Total long-term liabilities		8,666,988	8,515,206
Total liabilities		9,110,011	9,001,006
Equity and partners' capital
Total partners' capital		2,756,583	3,286,620
Noncontrolling interest		29,783	55,199
Total equity and partners' capital		2,786,366	3,341,819
Total liabilities, equity, and partners' capital		11,896,377	12,342,825
WES Operating [Member] | Common Units [Member]
Equity and partners' capital
Common units (318,675,578 units issued and outstanding at March 31, 2020, and December 31, 2019)		2,756,583	3,286,620
Affiliates [Member]
Current assets
Accounts receivable, net		124,900	113,300
Other current assets		9,000	5,000
Note receivable - Anadarko	[13]	257,885	260,000
Property, plant, and equipment
Other assets		59,700	60,200
Current liabilities
Accrued liabilities		2,500	3,100
Long-term liabilities
Other liabilities		107,800	97,800
Affiliates [Member] | WES Operating [Member]
Current assets
Accounts receivable, net		117,500	113,600
Other current assets		9,000	5,000
Note receivable - Anadarko	[14]	257,885	260,000
Property, plant, and equipment
Other assets		59,700	60,200
Current liabilities
Accrued liabilities		2,500	3,100
Long-term liabilities
Other liabilities		$ 107,800	$ 97,800
[1]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $124.9 million and $113.3 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019
[3]	Other assets includes related-party amounts of $59.7 million and $60.2 million as of March 31, 2020 , and December 31, 2019 , respectively. Other assets also includes $2.0 million and $4.5 million of NGLs line fill as of March 31, 2020 , and December 31, 2019 , respectively.
[4]	Short-term debt includes related-party amounts for finance leases of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively.
[5]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[6]	Other liabilities includes related-party amounts of $107.8 million and $97.8 million as of March 31, 2020 , and December 31, 2019 , respectively.
[7]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $117.5 million and $113.6 million as of March 31, 2020 , and December 31, 2019 , respectively.
[8]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019 , respectively.
[9]	Other assets includes related-party amounts of $59.7 million and $60.2 million as of March 31, 2020 , and December 31, 2019 , respectively. Other assets also includes $2.0 million and $4.5 million of NGLs line fill as of March 31, 2020 , and December 31, 2019 , respectively.
[10]	Short-term debt includes related-party amounts for finance leases of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively.
[11]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[12]	Other liabilities includes related-party amounts of $107.8 million and $97.8 million as of March 31, 2020 , and December 31, 2019 , respectively.
[13]	Note receivable – Anadarko is presented net of a $2.1 million allowance for expected credit losses as of March 31, 2020 . See Note 1 .
[14]	Note receivable – Anadarko is presented net of a $2.1 million allowance for expected credit losses as of March 31, 2020 . See Note 1 .

Consolidated Balance Sheets -_2

Consolidated Balance Sheets - WES Operating (Parenthetical) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Common units issued		443,971,409	443,971,409
Common units outstanding		443,971,409	443,971,409
Accounts receivable, net	[1]	$ 257,239	$ 260,512
Other current assets	[2]	81,027	41,938
Other assets	[3]	76,465	78,202
Accrued liabilities	[4]	166,738	149,793
Other liabilities	[5]	222,042	208,346
Natural-Gas Liquids [Member]
NGLs line fill inventory		2,000	4,500
Affiliates [Member]
Accounts receivable, net		124,900	113,300
Other current assets		9,000	5,000
Allowance for expected credit loss		2,100
Other assets		59,700	60,200
Finance leases - Short-term debt		2,600	7,900
Accrued liabilities		2,500	3,100
Other liabilities		107,800	97,800
WES Operating [Member]
Accounts receivable, net	[6]	249,843	260,748
Other current assets	[7]	79,324	39,914
Other assets	[8]	76,465	78,202
Accrued liabilities	[9]	160,175	149,639
Other liabilities	[10]	222,042	208,346
WES Operating [Member] | Natural-Gas Liquids [Member]
NGLs line fill inventory		2,000	4,500
WES Operating [Member] | Affiliates [Member]
Accounts receivable, net		117,500	113,600
Other current assets		9,000	5,000
Other assets		59,700	60,200
Finance leases - Short-term debt		2,600	7,900
Accrued liabilities		2,500	3,100
Other liabilities		$ 107,800	$ 97,800
Common Units [Member] | WES Operating [Member]
Common units issued		318,675,578	318,675,578
Common units outstanding		318,675,578	318,675,578
[1]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $124.9 million and $113.3 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019
[3]	Other assets includes related-party amounts of $59.7 million and $60.2 million as of March 31, 2020 , and December 31, 2019 , respectively. Other assets also includes $2.0 million and $4.5 million of NGLs line fill as of March 31, 2020 , and December 31, 2019 , respectively.
[4]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[5]	Other liabilities includes related-party amounts of $107.8 million and $97.8 million as of March 31, 2020 , and December 31, 2019 , respectively.
[6]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $117.5 million and $113.6 million as of March 31, 2020 , and December 31, 2019 , respectively.
[7]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019 , respectively.
[8]	Other assets includes related-party amounts of $59.7 million and $60.2 million as of March 31, 2020 , and December 31, 2019 , respectively. Other assets also includes $2.0 million and $4.5 million of NGLs line fill as of March 31, 2020 , and December 31, 2019 , respectively.
[9]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[10]	Other liabilities includes related-party amounts of $107.8 million and $97.8 million as of March 31, 2020 , and December 31, 2019 , respectively.

Consolidated Statements of Eq_3

Consolidated Statements of Equity and Partners' Capital - WES Operating - USD ($) $ in Thousands	Total		Chipeta [Member]	Net Investment by Anadarko [Member]		Common Units [Member]		General Partner [Member]	Noncontrolling Interest [Member]		Noncontrolling Interest [Member]Chipeta [Member]	WES Operating [Member]		WES Operating [Member]Chipeta [Member]	WES Operating [Member]Net Investment by Anadarko [Member]		WES Operating [Member]Common Units [Member]		WES Operating [Member]Class C Units [Member]		WES Operating [Member]General Partner [Member]		WES Operating [Member]Noncontrolling Interest [Member]	WES Operating [Member]Noncontrolling Interest [Member]Chipeta [Member]
Balance at Dec. 31, 2018	$ 4,892,683			$ 1,388,018		$ 951,888			$ 2,552,777			$ 4,919,597			$ 1,388,018		$ 2,475,540		$ 791,410		$ 206,862		$ 57,767
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	211,979			29,116		89,544			93,319			214,450			29,116		170,847		10,636		1,997		1,854
Distributions to noncontrolling interest owners			$ (1,935)								$ (1,935)			$ (1,935)										$ (1,935)
Distributions to WES Operating unitholders	(131,910)					(131,910)						(263,358)					(178,128)				(85,230)
Acquisitions from related parties	(2,007,501)	[1]		(2,141,827)	[1]	106,856	[1]		27,470	[1]		(2,007,501)	[2]		(2,141,827)	[2]	134,326	[2]
Contributions of equity-based compensation from Anadarko/Occidental	1,840					1,840						1,838					1,819				19
Net preacquisition contributions from (distributions to) related parties	451,591			451,591								451,591			451,591
Cumulative impact of the Merger transactions	0	[3]				3,169,800	[3]		(3,169,800)	[3]		0	[4]				926,236	[4]	(802,588)	[4]	(123,648)	[4]
Above-market component of swap agreements with Anadarko	7,407	[5]				7,407	[5]					7,407	[6]				7,407	[6]
Amortization of beneficial conversion feature of Class C units												0					(542)		542
Adjustments of net deferred tax liabilities	268,727			273,102		(4,375)						268,727			273,102		(4,375)
Other	(341)					(332)			(9)			268					268
Balance at Mar. 31, 2019	3,591,541			$ 0		3,437,922			153,619			3,591,084			$ 0		3,533,398		$ 0		$ 0		57,686
Balance at Dec. 31, 2019	3,345,293					3,209,947		$ (14,224)	149,570			3,341,819					3,286,620						55,199
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	(289,400)					(251,396)		(5,131)	(32,873)			(287,995)					(260,330)						(27,665)
Distributions to noncontrolling interest owners			$ (1,738)								$ (1,738)			$ (1,738)										$ (1,738)
Distributions to WES Operating unitholders	(281,786)					(276,151)		(5,635)				(290,314)					(290,314)
Acquisitions from related parties	0					(3,987)			3,987			0					(3,987)						3,987
Contributions of equity-based compensation from Anadarko/Occidental	4,105					4,105						4,105					4,105
Net contributions from (distributions to) related parties	20,489	[7]				489	[7]		20,000	[7]		20,489	[8]				20,489	[8]
Balance at Mar. 31, 2020	$ 2,792,285					$ 2,684,136		$ (24,990)	$ 133,139			$ 2,786,366					$ 2,756,583						$ 29,783
[1]	The amounts allocated to common unitholders and noncontrolling interests represent a non-cash investing activity related to the assets and liabilities assumed in the AMA acquisition.
[2]	The amount allocated to common unitholders represents a non-cash investing activity related to the assets and liabilities assumed in the AMA acquisition.
[3]	See Note 1 .
[4]	See Note 1 .
[5]	See Note 6 .
[6]	See Note 6 .
[7]	See December 2019 Agreements—Services, Secondment, and Employee Transfer Agreement within Note 1 .
[8]	See December 2019 Agreements—Services, Secondment, and Employee Transfer Agreement within Note 1 .

Consolidated Statements of Ca_3

Consolidated Statements of Cash Flows - WES Operating - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Cash flows from operating activities
Net income (loss)		$ (289,400)	$ 211,979
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		132,319	113,946
Long-lived asset impairments		155,785	390	$ 6,300
Goodwill impairment		441,017	0
Non-cash equity-based compensation expense		5,234	2,368
Deferred income taxes		(2,168)	4,065
Accretion and amortization of long-term obligations, net		2,100	1,511
Equity income, net – related parties		(61,347)	(57,992)
Distributions from equity-investment earnings – related parties		60,868	54,221
(Gain) loss on divestiture and other, net		40	590
(Gain) loss on early extinguishment of debt		(7,345)	0
(Gain) loss on interest-rate swaps		0	35,638
Other		2,287	7
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		7,702	9,486
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		(28,924)	(55,529)
Change in other items, net		(24,857)	22,393
Net cash provided by operating activities		393,311	343,073
Cash flows from investing activities
Capital expenditures		(172,816)	(386,144)
Contributions to equity investments - related parties		(10,960)	(36,543)
Distributions from equity investments in excess of cumulative earnings – related parties		5,052	7,792
Proceeds from the sale of assets to third parties		0	(33)
Net cash used in investing activities		(178,724)	(2,515,732)
Cash flows from financing activities
Borrowings, net of debt issuance costs	[1]	3,586,173	2,430,750
Repayments of debt	[2]	(3,470,139)	(467,595)
Increase (decrease) in outstanding checks		(7,308)	(5,890)
Distributions to WES Operating unitholders	[3]	(281,786)	(131,910)
Net contributions from (distributions to) related parties		20,489	451,591
Above-market component of swap agreements with Anadarko	[3]	0	7,407
Finance lease payments		(2,151)	0
Net cash provided by (used in) financing activities		(162,267)	2,180,564
Net increase (decrease) in cash and cash equivalents		52,320	7,905
Cash and cash equivalents at beginning of period		99,962	92,142	92,142
Cash and cash equivalents at end of period		152,282	100,047	99,962
Supplemental disclosures
Interest paid, net of capitalized interest		75,844	76,871
Taxes paid (reimbursements received)		(384)	96
Accrued capital expenditures		120,233	203,509
Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(1,738)	(1,935)
Affiliates [Member]
Cash flows from investing activities
Acquisitions		0	(2,007,501)
Cash flows from financing activities
Borrowings, net of debt issuance costs			11,000
Repayments of debt			(439,600)
Distributions to WES Operating unitholders		(150,609)	(102,654)
Third Parties [Member]
Cash flows from investing activities
Acquisitions		0	(93,303)
WES Operating [Member]
Cash flows from operating activities
Net income (loss)		(287,995)	214,450
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		132,319	113,946
Long-lived asset impairments		155,785	390
Goodwill impairment		441,017	0
Non-cash equity-based compensation expense		4,105	2,116
Deferred income taxes		(2,168)	4,065
Accretion and amortization of long-term obligations, net		2,100	1,490
Equity income, net – related parties		(61,347)	(57,992)
Distributions from equity-investment earnings – related parties		60,868	54,221
(Gain) loss on divestiture and other, net		40	590
(Gain) loss on early extinguishment of debt		(7,345)	0
(Gain) loss on interest-rate swaps		0	35,638
Other		2,287	7
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		15,334	7,974
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		(35,474)	(54,430)
Change in other items, net		(25,176)	21,577
Net cash provided by operating activities		394,350	344,042
Cash flows from investing activities
Capital expenditures		(172,816)	(386,144)
Contributions to equity investments - related parties		(10,960)	(36,543)
Distributions from equity investments in excess of cumulative earnings – related parties		5,052	7,792
Proceeds from the sale of assets to third parties		0	(33)
Net cash used in investing activities		(178,724)	(2,515,732)
Cash flows from financing activities
Borrowings, net of debt issuance costs	[4]	3,586,173	2,430,750
Repayments of debt	[5]	(3,470,139)	(439,595)
Increase (decrease) in outstanding checks		(7,308)	(5,890)
Distributions to WES Operating unitholders	[6]	(290,314)	(263,358)
Net contributions from (distributions to) related parties		20,489	451,591
Above-market component of swap agreements with Anadarko	[6]	0	7,407
Finance lease payments		(2,151)	0
Net cash provided by (used in) financing activities		(164,988)	2,178,970
Net increase (decrease) in cash and cash equivalents		50,638	7,280
Cash and cash equivalents at beginning of period		98,122	90,448	90,448
Cash and cash equivalents at end of period		148,760	97,728	$ 98,122
Supplemental disclosures
Interest paid, net of capitalized interest		75,844	76,637
Taxes paid (reimbursements received)		(384)	96
Accrued capital expenditures		120,233	203,509
WES Operating [Member] | Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(1,738)	(1,935)
WES Operating [Member] | Affiliates [Member]
Cash flows from investing activities
Acquisitions		0	(2,007,501)
Cash flows from financing activities
Borrowings, net of debt issuance costs			11,000
Repayments of debt			(439,600)
Distributions to WES Operating unitholders		(290,314)	(164,902)
WES Operating [Member] | Third Parties [Member]
Cash flows from investing activities
Acquisitions		$ 0	$ (93,303)
[1]	For the three months ended March 31, 2019 , includes an $11.0 million
[2]	For the three months ended March 31, 2019 , includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6 .
[3]	See Note 6 .
[4]	For the three months ended March 31, 2019 , includes an $11.0 million borrowing under the APCWH Note Payable.
[5]	For the three months ended March 31, 2019 , includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6 .
[6]	See Note 6 .

Consolidated Statements of Ca_4

Consolidated Statements of Cash Flows - WES Operating (Parenthetical) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Borrowings, net of debt issuance costs	[1]	$ 3,586,173	$ 2,430,750
Repayments of debt	[2]	3,470,139	467,595
WES Operating [Member]
Borrowings, net of debt issuance costs	[3]	3,586,173	2,430,750
Repayments of debt	[4]	$ 3,470,139	439,595
Affiliates [Member]
Borrowings, net of debt issuance costs			11,000
Repayments of debt			439,600
Affiliates [Member] | WES Operating [Member]
Borrowings, net of debt issuance costs			11,000
Repayments of debt			$ 439,600
[1]	For the three months ended March 31, 2019 , includes an $11.0 million
[2]	For the three months ended March 31, 2019 , includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6 .
[3]	For the three months ended March 31, 2019 , includes an $11.0 million borrowing under the APCWH Note Payable.
[4]	For the three months ended March 31, 2019 , includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6 .

Description of Business and Bas

Description of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION General. Western Midstream Partners, LP (formerly Western Gas Equity Partners, LP) is a Delaware master limited partnership formed in September 2012. Western Midstream Operating, LP (formerly Western Gas Partners, LP, and together with its subsidiaries, “WES Operating”) is a Delaware limited partnership formed by Anadarko Petroleum Corporation in 2007 to acquire, own, develop, and operate midstream assets. Western Midstream Partners, LP owns, directly and indirectly, a 98.0% limited partner interest in WES Operating, and directly owns all of the outstanding equity interests of Western Midstream Operating GP, LLC, which holds the entire non-economic general partner interest in WES Operating. “Anadarko” refers to Anadarko Petroleum Corporation and its subsidiaries, excluding Western Midstream Holdings, LLC. Anadarko became a wholly owned subsidiary of Occidental Petroleum Corporation as a result of Occidental Petroleum Corporation’s acquisition by merger of Anadarko on August 8, 2019. For purposes of these consolidated financial statements, the “Partnership” refers to Western Midstream Partners, LP in its individual capacity or to Western Midstream Partners, LP and its subsidiaries, including Western Midstream Operating GP, LLC and WES Operating, as the context requires. “WES Operating GP” refers to Western Midstream Operating GP, LLC, individually as the general partner of WES Operating. The Partnership’s general partner, Western Midstream Holdings, LLC (the “general partner”), is a wholly owned subsidiary of Occidental Petroleum Corporation. “Occidental” refers to Occidental Petroleum Corporation, as the context requires, and its subsidiaries, excluding the general partner. “Related parties” refers to Occidental and the Partnership’s equity interests in Fort Union Gas Gathering, LLC (“Fort Union”), White Cliffs Pipeline, LLC (“White Cliffs”), Rendezvous Gas Services, LLC (“Rendezvous”), Enterprise EF78 LLC (the “Mont Belvieu JV”), Texas Express Pipeline LLC (“TEP”), Texas Express Gathering LLC (“TEG”), Front Range Pipeline LLC (“FRP”), Whitethorn Pipeline Company LLC (“Whitethorn LLC”), Cactus II Pipeline LLC (“Cactus II”), Saddlehorn Pipeline Company, LLC (“Saddlehorn”), Panola Pipeline Company, LLC (“Panola”), Mi Vida JV LLC (“Mi Vida”), Ranch Westex JV LLC (“Ranch Westex”), and Red Bluff Express Pipeline, LLC (“Red Bluff Express”). 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 “West Texas complex” refers to the Delaware Basin Midstream, LLC (“DBM”) complex and DBJV and Haley systems. 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 its capacity as a natural-gas processor, the Partnership also buys and sells natural gas, NGLs, and condensate on behalf of itself and as an agent for its customers under certain contracts. The Partnership provides the above-described midstream services for Occidental and third-party customers. As of March 31, 2020 , the Partnership’s assets and investments consisted of the following: Wholly Owned and Operated Operated Interests Non-Operated Interests Equity Interests Gathering systems (1) 17 2 3 2 Treating facilities 38 3 — 3 Natural-gas processing plants/trains 26 3 — 5 NGLs pipelines 2 — — 4 Natural-gas pipelines 5 — — 1 Crude-oil pipelines 3 1 — 3 (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. Latham Train II, a cryogenic train at the DJ Basin complex, and Loving ROTF Train III, an oil-stabilization train at the DBM oil system, commenced operations during the first quarter of 2020. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) December 2019 Agreements . On December 31, 2019, (i) the Partnership and certain of its subsidiaries, including WES Operating and WES Operating GP, entered into the below-described agreements with Occidental and/or certain of its subsidiaries, including Anadarko, and (ii) WES Operating entered into the below-described amendments to its debt agreements (collectively, the “ December 2019 Agreements ”). • Exchange Agreement. Western Gas Resources, Inc. (“WGRI”), the general partner, and the Partnership entered into a partnership interests exchange agreement (the “Exchange Agreement”), pursuant to which the Partnership canceled the non-economic general partner interest in the Partnership and simultaneously issued a 2.0% general partner interest to the general partner in exchange for which WGRI transferred 9,060,641 common units to the Partnership, which immediately canceled such units on receipt. • Services, Secondment, and Employee Transfer Agreement. Occidental, Anadarko, and WES Operating GP entered into an amended and restated Services, Secondment, and Employee Transfer Agreement (the “Services Agreement”), pursuant to which Occidental, Anadarko, and their subsidiaries (i) seconded certain personnel employed by Occidental to WES Operating GP, in exchange for which WES Operating GP pays a monthly secondment and shared services fee to Occidental equivalent to the direct cost of the seconded employees until their transfer to the Partnership and (ii) agreed to continue to provide certain administrative and operational services to the Partnership for up to a two-year transition period. In January 2020, pursuant to the Services Agreement, Occidental made a one-time cash contribution of $20.0 million to WES Operating for anticipated transition costs required to establish stand-alone human resources and information technology functions. The Services Agreement also includes provisions governing the transfer of certain employees to the Partnership and the assumption by the Partnership of liabilities relating to those employees at the time of their transfer. In late March 2020, seconded employees’ employment was transferred to the Partnership. • RCF amendment. WES Operating entered into an amendment to its $2.0 billion senior unsecured revolving credit facility (“RCF”) to, among other things, (i) effective on February 14, 2020, exercise the final one-year extension option to extend the maturity date of the RCF to February 14, 2025, for the extending lenders, and (ii) modify the change of control definition to provide, among other things, that, subject to certain conditions, if the limited partners of the Partnership elect to remove the general partner as the general partner of the Partnership in accordance with the terms of the partnership agreement, then such removal will not constitute a change of control under the RCF. • Term loan facility amendment. WES Operating entered into an amendment of its $3.0 billion senior unsecured credit facility (“Term loan facility”) to, among other things, modify the change of control definition to provide, among other things, that, subject to certain conditions, if the limited partners of the Partnership elect to remove the general partner as the general partner of the Partnership in accordance with the terms of the partnership agreement, then such removal will not constitute a change of control under the Term loan facility. See Note 11 . • Termination of debt-indemnification agreements. WES Operating GP and certain wholly owned subsidiaries of Occidental mutually terminated the debt-indemnification agreements related to certain indebtedness incurred by WES Operating. • Termination of omnibus agreements. The Partnership and WES Operating entered into agreements with Occidental to terminate the WES and WES Operating omnibus agreements. See Note 6 . 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Merger transactions . On February 28, 2019, the Partnership, WES Operating, Anadarko, and certain of their affiliates completed the transactions contemplated by the Contribution Agreement and Agreement and Plan of Merger (the “Merger Agreement”), dated November 7, 2018, pursuant to which, among other things, (i) Clarity Merger Sub, LLC, a wholly owned subsidiary of the Partnership, merged with and into WES Operating, with WES Operating continuing as the surviving entity and as a subsidiary of the Partnership (the “Merger”), and (ii) WES Operating acquired the Anadarko Midstream Assets (“AMA”) (see Note 3 ). Basis of presentation. 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, including WES Operating and WES Operating GP. All significant intercompany transactions have been eliminated. The following table outlines the ownership interests and the accounting method of consolidation used in the consolidated financial statements for entities not wholly owned: Percentage Interest Full consolidation Chipeta (1) 75.00 % Proportionate consolidation (2) Springfield system 50.10 % Marcellus Interest systems 33.75 % Equity investments (3) Mi Vida 50.00 % Ranch Westex 50.00 % FRP 33.33 % Red Bluff Express 30.00 % Mont Belvieu JV 25.00 % Rendezvous 22.00 % TEP 20.00 % TEG 20.00 % Whitethorn LLC 20.00 % Saddlehorn 20.00 % Cactus II 15.00 % Panola 15.00 % Fort Union 14.81 % White Cliffs 10.00 % (1) The 25% third-party interest in Chipeta Processing LLC (“Chipeta”) is reflected within noncontrolling interests in the consolidated financial statements. See Noncontrolling interests below. (2) The Partnership proportionately consolidates its associated share of the assets, liabilities, revenues, and expenses attributable to these assets. (3) Investments in non-controlled entities over which the Partnership exercises significant influence are accounted for under the equity method of accounting. “Equity-investment throughput” refers to the Partnership’s share of average throughput for these investments. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) The consolidated financial results of WES Operating are included in the Partnership’s consolidated financial statements. Throughout these notes to consolidated financial statements, and to the extent material, any differences between the consolidated financial results of the Partnership and WES Operating are discussed separately. The Partnership’s consolidated financial statements differ from those of WES Operating primarily as a result of (i) the presentation of noncontrolling interest ownership (see Noncontrolling interests below and Note 5 ), (ii) the elimination of WES Operating GP’s investment in WES Operating with WES Operating GP’s underlying capital account, (iii) the general and administrative expenses incurred by the Partnership, which are separate from, and in addition to, those incurred by WES Operating, (iv) the inclusion of the impact of Partnership equity balances and Partnership distributions, and (v) the senior secured revolving credit facility (“WGP RCF”) until its repayment in March 2019. See Note 11 . Presentation of the Partnership’s assets. The Partnership’s assets include assets owned and ownership interests accounted for by the Partnership under the equity method of accounting, through its 98.0% partnership interest in WES Operating as of March 31, 2020 (see Note 7 ). The Partnership also owns and controls the entire non-economic general partner interest in WES Operating GP, and the Partnership’s general partner is owned by Occidental. 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 reasonable methods. Changes in facts and circumstances or additional information may result in revised estimates and actual results may differ from these estimates. Effects on the business, financial condition, and results of operations resulting from revisions to estimates are recognized when the facts that give rise to the revisions become known. The information included herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the consolidated financial statements, and certain prior-period amounts have been reclassified to conform to the current-year presentation. Noncontrolling interests. For periods subsequent to Merger completion, the Partnership’s noncontrolling interests in the consolidated financial statements consist of (i) the 25% third-party interest in Chipeta and (ii) the 2.0% Occidental subsidiary-owned limited partner interest in WES Operating. For periods prior to Merger completion, the Partnership’s noncontrolling interests in the consolidated financial statements consisted of (i) the 25% third-party interest in Chipeta, (ii) the publicly held limited partner interests in WES Operating, (iii) the common units issued by WES Operating to subsidiaries of Anadarko as part of the consideration paid for prior-period acquisitions from Anadarko, and (iv) the Class C units issued by WES Operating to a subsidiary of Anadarko as part of the funding for the acquisition of DBM. For all periods presented, WES Operating’s noncontrolling interest in the consolidated financial statements consists of the 25% third-party interest in Chipeta. See Note 5 . When WES Operating issues equity, the carrying amount of the noncontrolling interest reported by the Partnership is adjusted to reflect the noncontrolling ownership interest in WES Operating. The resulting impact of such noncontrolling interest adjustment on the Partnership’s interest in WES Operating is reflected as an adjustment to the Partnership’s partners’ capital. Shutdown of gathering systems. In May 2018, after assessing a number of factors, and with the safety of the community and the protection of the environment as primary factors, the Partnership permanently ceased operations at the Kitty Draw gathering system in Wyoming (part of the Hilight system) and the Third Creek gathering system in Colorado (part of the DJ Basin complex). An accrual of $10.9 million for anticipated costs associated with system shutdowns was recorded in 2018 as a reduction in related-party Product sales in the consolidated statements of operations. During the first quarter of 2019, $5.5 million of the accrual related to the Kitty Draw gathering system was reversed due to producer settlements being less than their initial estimates. Segments. The Partnership’s operations continue to be organized into a single operating segment, the assets of which gather, compress, treat, process, and transport natural gas; gather, stabilize, and transport condensate, NGLs, and crude oil; and gather and dispose of produced water in the United States. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Equity-based compensation. On February 10, 2020, the Board of Directors approved awards of phantom units (the “Awards”) to the Partnership’s executive officers under the Western Gas Equity Partners, LP 2012 Long-Term Incentive Plan. The Awards include (i) an award of time-vested phantom units that vest ratably over a three-year period (“Time-Based Awards”), (ii) a market award that vests after a three-year performance period based on the Partnership’s relative total unitholder return as compared to a group of peer companies (“TUR Awards”), and (iii) a performance award that vests based on the Partnership’s average return on assets over a three-year performance period (“ROA Awards”). At vesting, the value of the TUR Awards and the ROA Awards will be determined in accordance with the terms of the respective Award Agreements that provide for payout percentages ranging from 0% to 200% based on results achieved over the applicable performance period. At vesting, the Awards generally will be settled in Partnership common units. Prior to vesting, the Awards pay in-kind distributions in the form of Partnership common units. In addition, phantom units are awarded under the Western Gas Equity Partners, LP 2012 Long-Term Incentive Plan to non-executive employees of the Partnership from time to time. These time-vested phantom units vest ratably over a three-year period and, prior to vesting, pay distribution equivalents in cash. The Partnership accounts for these equity-classified awards at fair value. The equity-based compensation expense attributable to these awards is amortized over a three-year service period using the straight-line method. Expense is recognized based on the grant-date fair value and recorded, net of any forfeitures, as General and administrative expense in the consolidated statements of operations. The fair value of the Time-based Awards, ROA Awards, and non-executive awards is based on the observable market price of the Partnership’s units on the grant date of the award. The fair value of the TUR Awards is determined using a Monte Carlo simulation. Defined-contribution plan. Beginning in the first quarter of 2020, employees of the Partnership are eligible to participate in the Western Midstream Savings Plan, a defined-contribution benefit plan maintained by the Partnership. All regular employees may participate in the plan by making elective contributions that are matched by the Partnership, subject to certain limitations. The Partnership also makes other contributions based on plan guidelines. The Partnership recognized expense related to the plan of $0.4 million for the three months ended March 31, 2020, recorded as General and administrative expense in the consolidated statements of operations. Recently adopted accounting standards. Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326) significantly changes the accounting and disclosure requirements related to credit losses on financial assets. Under the new standard, entities are now required to estimate lifetime expected credit losses for trade receivables, loans, and other financial instruments as of the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts, resulting in earlier recognition of credit losses. There was no impact to the consolidated financial statements with the Partnership’s adoption of the standard on January 1, 2020. The Partnership has implemented the necessary changes to its processes and controls to support accounting and disclosure requirements under this ASU. Accounts receivable and contract assets. Accounts receivable represent contractual rights for services performed, with, on average, 30-day payment terms. Contract assets primarily relate to accrued deficiency fees and revenue accrued but not yet billed under cost-of-service contracts. As of March 31, 2020, there have been no negative indications regarding the collectability of these receivables as it relates to impacts from the global outbreak of the coronavirus (“COVID-19”) and the oil-market disruption resulting from significantly lower global demand and corresponding oversupply of crude oil. The Partnership will continue to monitor the credit quality of its customer base and assess collectability of these assets as appropriate. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Notes receivable. In May 2008, WES Operating 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 “Anadarko note receivable”). Following Occidental’s acquisition by merger of Anadarko in August 2019, Occidental became the ultimate counterparty. As of March 31, 2020, the Partnership assessed the recoverability of the Anadarko note receivable under the loss-given-default method using historical data from internal and external sources, current market conditions, and reasonable and supportable forecasted information. The loss-given-default approach was based on applicable probability of default percentages for similar debt instruments and the fair value of the Anadarko note receivable, which reflects an analysis of Occidental’s yield based on quoted market yields of similar Occidental debt instruments. As of March 31, 2020, the Partnership recognized an allowance for expected credit losses of $2.1 million related to the note receivable. See Note 6 .

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	2. REVENUE FROM CONTRACTS WITH CUSTOMERS The following table summarizes revenue from contracts with customers: Three Months Ended thousands 2020 2019 Revenue from customers Service revenues – fee based $ 641,921 $ 579,974 Service revenues – product based 15,921 19,379 Product sales 56,649 72,800 Total revenue from customers 714,491 672,153 Revenue from other than customers Lease revenue (1) 59,475 — Net gains (losses) on commodity-price swap agreements — (667 ) Other 347 397 Total revenues and other $ 774,313 $ 671,883 (1) For the three months ended March 31, 2020 , includes fixed- and variable-lease revenue from an operating and maintenance agreement entered into with Occidental. See Operating lease within Note 6 . Contract balances. Receivables from customers, which are included in Accounts receivable, net on the consolidated balance sheets were $331.8 million and $362.6 million as of March 31, 2020 , and December 31, 2019 , respectively. Contract assets primarily relate to accrued deficiency fees the Partnership expects to charge customers once the related performance periods are completed and revenue accrued but not yet billed under cost-of-service contracts with fixed and variable fees. The following table summarizes current-period activity related to contract assets from contracts with customers: thousands Balance at December 31, 2019 $ 67,357 Additional estimated revenues recognized 5,365 Balance at March 31, 2020 $ 72,722 Contract assets at March 31, 2020 Other current assets $ 12,975 Other assets 59,747 Total contract assets from contracts with customers $ 72,722 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 current-period activity related to contract liabilities from contracts with customers: thousands Balance at December 31, 2019 $ 222,274 Cash received or receivable, excluding revenues recognized during the period 11,203 Revenues recognized that were included in the contract liability balance at the beginning of the period (8,893 ) Balance at March 31, 2020 $ 224,584 Contract liabilities at March 31, 2020 Accrued liabilities $ 9,120 Other liabilities 215,464 Total contract liabilities from contracts with customers $ 224,584 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, 2020 , are presented 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 portion of expected future revenues from existing contracts as most future revenues from customers are dependent on future variable customer volumes and, in some cases, variable commodity prices for those volumes. thousands Remainder of 2020 $ 572,077 2021 779,098 2022 1,035,119 2023 978,409 2024 948,700 Thereafter 3,547,074 Total $ 7,860,477

Acquisitions and Divestitures

Acquisitions and Divestitures	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Acquisitions and Divestitures	3. ACQUISITIONS AND DIVESTITURES AMA acquisition. In February 2019, WES Operating acquired AMA from Anadarko, which is comprised of (i) the DJ Basin oil system and Wattenberg processing plant located in the DJ basin; (ii) the DBM oil system, APC water systems, a 50% interest in Mi Vida, and a 50% interest in Ranch Westex, located in West Texas; (iii) the Wamsutter pipeline located in Wyoming; (iv) a 20% interest in Saddlehorn, a crude-oil and condensate pipeline that originates in Laramie County, Wyoming and terminates in Cushing, Oklahoma; and (v) a 15% interest in Panola, an NGLs pipeline that originates in Panola County, Texas, and terminates in Mont Belvieu, Texas. AMA was acquired in exchange for aggregate consideration of $2.0 billion of cash, less the outstanding amount payable pursuant to an intercompany note (the “APCWH Note Payable”) assumed by WES Operating in connection with the transfer, and 45,760,201 WES Operating common units. These WES Operating common units, less 6,375,284 WES Operating common units retained by WGRAH, converted into the right to receive common units of the Partnership at Merger completion. Red Bluff Express acquisition. In January 2019, the Partnership acquired a 30% interest in Red Bluff Express, which owns a natural-gas pipeline operated by a third party that connects processing plants in Reeves and Loving Counties, Texas, to the WAHA hub in Pecos County, Texas. The Partnership acquired its 30% interest from a third party via an initial net investment of $92.5 million , which represented its share of costs incurred up to the date of acquisition. The initial investment was funded with cash on hand and the interest in Red Bluff Express is accounted for under the equity method of accounting.

Partnership Distributions

Partnership Distributions	3 Months Ended
	Mar. 31, 2020
Distributions Made to Members or Limited Partners [Abstract]
Partnership Distributions	4. PARTNERSHIP DISTRIBUTIONS Partnership distributions. The partnership agreement requires the Partnership to distribute all of its available cash (as defined in its partnership agreement) to unitholders of record on the applicable record date within 55 days following each quarter’s end. The Board of Directors declared the following cash distributions to the Partnership’s unitholders for the periods presented: thousands except per-unit amounts Quarters Ended Total Quarterly Total Quarterly Distribution 2019 March 31 $ 0.61000 $ 276,324 May 2019 June 30 0.61800 279,959 August 2019 September 30 0.62000 280,880 November 2019 December 31 0.62200 281,786 February 2020 2020 March 31 (1) $ 0.31100 $ 140,893 May 2020 (1) The Board of Directors declared a cash distribution to the Partnership’s unitholders for the first quarter of 2020 of $0.31100 per unit, or $140.9 million in aggregate. The cash distribution is payable on May 14, 2020 to unitholders of record at the close of business on May 1, 2020 , including the general partner units that were issued on December 31, 2019 (see Note 1 ). Following the transactions contemplated by the Exchange Agreement, the general partner is entitled to 2.0% of all quarterly distributions beginning with the cash distribution declared for the fourth quarter of 2019. 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 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 unitholder distributions 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 generally are intended to be repaid or refinanced within 12 months. In all cases, working capital borrowings are used solely for working capital purposes or to fund unitholder distributions. WES Operating partnership distributions. Immediately prior to the closing of the Merger, the WES Operating IDRs and general partner units were converted into WES Operating common units and a non-economic general partner interest in WES Operating, and at Merger completion, all WES Operating common units held by the public and subsidiaries of Anadarko (other than common units held by the Partnership, WES Operating GP, and 6.4 million common units held by a subsidiary of Anadarko) were converted into common units of the Partnership. Beginning with the first quarter of 2019, WES Operating has made cash distributions to the Partnership and WGRAH, a subsidiary of Occidental, in respect of their proportionate share of limited partner interests in WES Operating. See Note 5 . WES Operating made the following cash distributions to its limited partners for the periods presented: thousands Quarters Ended Total Quarterly 2019 March 31 $ 283,271 June 30 288,083 September 30 289,676 December 31 290,314 2020 March 31 $ 143,404

Equity and Partners' Capital

Equity and Partners' Capital	3 Months Ended
	Mar. 31, 2020
Partners' Capital Notes [Abstract]
Equity and Partners' Capital	5. EQUITY AND PARTNERS’ CAPITAL Holdings of Partnership equity. The Partnership’s common units are listed on the New York Stock Exchange under the ticker symbol “WES.” As of March 31, 2020 , Occidental held 242,136,976 common units, representing a 53.4% limited partner interest in the Partnership, and through its ownership of the general partner, Occidental indirectly held 9,060,641 general partner units, representing a 2.0% general partner interest in the Partnership (see Note 1 ). The public held 201,834,433 common units, representing a 44.6% limited partner interest in the Partnership. Holdings of WES Operating equity. As of March 31, 2020 , (i) the Partnership, directly and indirectly through its ownership of WES Operating GP, owned a 98.0% limited partner interest and the entire non-economic general partner interest in WES Operating and (ii) Occidental, through its ownership of WGRAH, owned a 2.0% limited partner interest in WES Operating, which is reflected as a noncontrolling interest within the consolidated financial statements of the Partnership (see Note 1 ). WES Operating Class C units. In November 2014, WES Operating issued 10,913,853 Class C units to AMH, pursuant to a Unit Purchase Agreement with Anadarko and AMH. The Class C units were issued to partially fund the acquisition of DBM. All outstanding Class C units converted into WES Operating common units on a one -for-one basis immediately prior to the closing of the Merger (see Note 1 ). Partnership’s net income (loss) per common unit. Following the transactions contemplated by the Exchange Agreement, the common and general partner unitholders’ allocation of net income (loss) attributable to the Partnership was equal to their cash distributions plus their respective allocations of undistributed earnings or losses using the two-class method. Specifically, net income equal to the amount of available cash (as defined by the partnership agreement) was allocated to the common and general partner unitholders consistent with actual cash distributions and capital account allocations. Undistributed earnings (net income in excess of distributions) or undistributed losses (available cash in excess of net income (loss)) were then allocated to the common and general partner unitholders in accordance with their weighted-average ownership percentage during each period. The Partnership’s basic net income (loss) per common unit is calculated by dividing the limited partners’ interest in net income (loss) by the weighted-average number of common units outstanding during the period. Net income (loss) attributable to assets acquired from Anadarko for periods prior to the acquisition of such assets was not allocated to the limited partners when calculating net income (loss) per common unit. WES Operating’s net income (loss) per common unit. For periods subsequent to the closing of the Merger, net income (loss) per common unit for WES Operating is not calculated as it no longer has any publicly traded units outstanding.

Related-Party Transactions

Related-Party Transactions	3 Months Ended
	Mar. 31, 2020
Related Party Fees and Other Arrangements, Limited Liability Company (LLC) or Limited Partnership (LP) [Abstract]
Related-Party Transactions	6. RELATED-PARTY TRANSACTIONS Summary of related-party transactions. The following table summarizes material related-party transactions included in the Partnership’s consolidated financial statements: Three Months Ended thousands 2020 2019 Revenues and other $ 482,385 $ 378,437 Equity income, net – related parties 61,347 57,992 Operating expenses Cost of product 77,903 56,172 Operation and maintenance 32,841 39,141 General and administrative (1) 21,855 18,894 Total operating expenses 132,599 114,207 Interest income (2) 4,225 4,225 Interest expense (3) 43 1,833 APCWH Note Payable borrowings — 11,000 Repayment of APCWH Note Payable — 439,595 Distributions to Partnership unitholders (4) 150,609 102,654 Distributions to WES Operating unitholders (5) 5,807 2,543 Above-market component of swap agreements with Anadarko — 7,407 (1) Includes amounts charged by Occidental pursuant to the shared services agreements (see Shared services agreements within this Note 6 ) . Also see Incentive Plans within this Note 6 . (2) Represents interest income recognized on the Anadarko note receivable. (3) Includes amounts related to finance leases for the three months ended March 31, 2020 , and the APCWH Note Payable for the three months ended March 31, 2019 (see Note 11 ) . (4) Represents distributions paid to Occidental pursuant to the partnership agreement of the Partnership (see Note 4 and Note 5 ). (5) Represents distributions paid to certain subsidiaries of Occidental pursuant to WES Operating’s partnership agreement (see Note 4 and Note 5 ). The following table summarizes material related-party transactions for WES Operating (which are included in the Partnership’s consolidated financial statements) to the extent the amounts differ from the Partnership’s consolidated financial statements: Three Months Ended thousands 2020 2019 General and administrative (1) $ 21,738 $ 18,498 Distributions to WES Operating unitholders (2) 290,314 164,902 (1) Includes amounts charged by Occidental pursuant to the shared services agreements (see Shared services agreements within this Note 6 ). Also see Incentive Plans within this Note 6 . (2) Represents distributions paid to the Partnership and certain subsidiaries of Occidental pursuant to WES Operating’s partnership agreement (see Note 4 and Note 5 ). For the three months ended March 31, 2019 , includes distributions to the Partnership and a subsidiary of Occidental related to the repayment of the WGP RCF (see Note 11 ). 6. RELATED-PARTY TRANSACTIONS (CONTINUED) Related-party transactions. Related-party revenues include (i) income from the Partnership’s investments accounted for under the equity method of accounting (see Note 7 ) and (ii) amounts earned by the Partnership from services provided to Occidental and from the sale of natural gas, condensate, and NGLs to Occidental. Occidental sells natural gas and NGLs as an agent on behalf of either the Partnership or the Partnership’s customers. When product sales are on the Partnership’s customers’ behalf, the Partnership recognizes associated service revenues and cost of product expense. When product sales are on the Partnership’s behalf, the Partnership recognizes product sales revenues based on Occidental’s sales price to the third party and records the associated cost of product expense. In addition, the Partnership purchases natural gas from an affiliate of Occidental pursuant to gas purchase agreements. Operation and maintenance expense includes amounts accrued for or paid to related parties for the operation of the Partnership’s assets and for services provided to related parties, including field labor, measurement and analysis, and other disbursements. A portion of general and administrative expense is paid by Occidental, which results in related-party transactions pursuant to the reimbursement provisions of the Partnership’s and WES Operating’s agreements with Occidental. Related-party expenses do not bear a direct relationship to related-party revenues, and third-party expenses do not bear a direct relationship to third-party revenues. Operating lease . Effective December 31, 2019, an affiliate of Occidental and a wholly owned subsidiary of the Partnership, entered into an operating and maintenance agreement, pursuant to which Occidental provides operational and maintenance services with respect to a crude-oil gathering system and associated treating facilities owned by the Partnership through December 31, 2021. The agreement and underlying contracts include (i) fixed consideration, which is measured as the minimum-volume commitment for both gathering and treating, and (ii) variable consideration, which consists of all volumes above the minimum-volume commitment. Subsequent to the initial two-year term, the agreement provides for automatic one-year extensions, unless either party exercises its option to terminate the lease with advance notice. For the three months ended March 31, 2020 , the Partnership recognized fixed-lease revenue of $43.9 million and variable-lease revenue of $15.6 million related to these agreements, with such amounts included in Service revenues – fee based in the consolidated statement of operations. December 2019 Agreements . As discussed in more detail in Note 1 , on December 31, 2019, the Partnership and certain of its subsidiaries, including WES Operating and WES Operating GP, entered into agreements with Occidental and/or certain of its subsidiaries, including Anadarko. Merger transactions. As discussed in more detail in Note 1 , on February 28, 2019, the Partnership, WES Operating, Anadarko, and certain of their affiliates completed the Merger and the other transactions contemplated in the Merger Agreement, which included the acquisition of AMA from Anadarko. See Note 3 . Note receivable - Anadarko. In May 2008, WES Operating 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 and classified as Interest income – related parties in the consolidated statements of operations. As of March 31, 2020 , the accrued interest receivable balance of $2.8 million is classified as Accounts receivable, net on the consolidated balance sheets. The fair value of the Anadarko note receivable was $153.6 million and $337.7 million at March 31, 2020 , and December 31, 2019 , respectively. Following Occidental’s acquisition by merger of Anadarko, the fair value of the Anadarko note receivable reflects an analysis of Occidental’s yield based on quoted market yields of similar Occidental debt instruments. Accordingly, the fair value of the Anadarko note receivable is measured using Level-2 fair value inputs. As of March 31, 2020, the Partnership recognized an allowance for expected credit losses of $2.1 million related to the Anadarko note receivable. See Note 1 . APCWH Note Payable. In June 2017, APC Water Holdings 1, LLC (“APCWH”) entered into an eight-year note payable agreement with Anadarko, which was repaid in the first quarter of 2019 at the Merger completion date. See Note 11 . 6. RELATED-PARTY TRANSACTIONS (CONTINUED) Commodity-price swap agreements. WES Operating previously entered into commodity-price swap agreements with Anadarko to mitigate exposure to the commodity-price risk inherent in WES Operating’s percent-of-proceeds, percent-of-product, and keep-whole natural-gas processing contracts. These commodity-price swap agreements expired without renewal on December 31, 2018. Notional volumes for each product-based commodity-price swap agreement were not specifically defined. Instead, the commodity-price swap agreements applied to the actual volumes of natural gas, condensate, and NGLs purchased and sold. The commodity-price swap agreements did not satisfy the definition of a derivative financial instrument and, therefore did not require fair-value measurement. Net gains (losses) on commodity-price swap agreements were $(0.7) million (due to settlement of 2018 activity in 2019) for the three months ended March 31, 2019 , reported in the consolidated statements of operations as related-party Product sales. A capital contribution from Anadarko related to the commodity-price swap agreements of $7.4 million was recorded in the consolidated statements of equity and partners’ capital for the three months ended March 31, 2019 . Gathering and processing agreements. The Partnership has significant gathering and processing arrangements with affiliates of Occidental on most of its systems. These arrangements with Occidental include Occidental-produced volumes and in some instances, the volumes of other working-interest owners of Occidental where the joint partnership collectively markets volumes. These volumes are considered owned and controlled by Occidental, who is the contracting counterparty of the Partnership. Natural-gas throughput (excluding equity-investment throughput) attributable to production owned or controlled by Occidental was 42% and 36% for the three months ended March 31, 2020 and 2019 , respectively. Crude-oil and NGLs throughput (excluding equity-investment throughput) attributable to production owned or controlled by Occidental was 89% and 81% for the three months ended March 31, 2020 and 2019 , respectively. Produced-water throughput attributable to production owned or controlled by Occidental was 89% and 84% for the three months ended March 31, 2020 and 2019 , respectively. Commodity purchase and sale agreements. The Partnership sells a significant amount of its natural gas and NGLs to Anadarko Energy Services Company (“AESC”), Occidental’s marketing affiliate that acts as the Partnership’s agent for third-party sales. In addition, the Partnership purchases natural gas from AESC pursuant to purchase agreements. Marketing Transition Services Agreement. Effective December 31, 2019, certain subsidiaries of Anadarko entered into a transition services agreement (the “Marketing Transition Services Agreement”) to provide certain marketing-related services to certain of the Partnership’s subsidiaries through December 31, 2020, subject to the Partnership’s subsidiaries’ option to extend such services for an additional six-month period. Additionally, under the terms of the Marketing Transition Services Agreement, the Partnership is liable for certain downstream transportation commitments through December 31, 2020. Shared services agreements. Pursuant to the agreements discussed below, Occidental performs certain centralized corporate functions for the Partnership and WES Operating. Services Agreement. Pursuant to the Services Agreement, which was amended and restated on December 31, 2019, specified employees of Occidental were seconded to WES Operating GP to provide, under the direction, supervision, and control of the general partner, (i) operating and routine maintenance service and (ii) corporate, administrative, and other services, with respect to the assets owned and operated by the Partnership. Occidental is reimbursed for the services provided by the seconded employees. In late March 2020, seconded employees’ employment was transferred to the Partnership. Further, Occidental continues to provide certain administrative and operational services to the Partnership. In January 2020, pursuant to the Services Agreement, Occidental made a one-time cash contribution of $20.0 million to WES Operating for anticipated transition costs required to establish stand-alone human resources and information technology functions. For additional information on the Services Agreement, see Note 1 . 6. RELATED-PARTY TRANSACTIONS (CONTINUED) WES and WES Operating omnibus agreements. Prior to December 31, 2019, the Partnership had an omnibus agreement with Occidental and the general partner and WES Operating had a separate omnibus agreement with Occidental and WES Operating GP. These agreements governed, among other things, the obligation to reimburse Occidental for expenses incurred or payments made on the Partnership’s and WES Operating’s behalf in conjunction with general and administrative services provided by Occidental. The omnibus agreements were terminated as part of the December 2019 Agreements (see Note 1 ). Incentive Plans. General and administrative expense includes equity-based compensation expense allocated to the Partnership by Occidental for awards granted to the executive officers of the general partner and to other employees prior to their employment with the Partnership under (i) the Anadarko Petroleum Corporation 2012 Omnibus Incentive Compensation Plan, as amended and restated, (ii) Occidental’s 2015 Long-Term Incentive Plan, and (iii) Occidental’s Phantom Share Unit Award Plan (collectively referred to as the “Incentive Plans”). General and administrative expense includes costs related to the Incentive Plans of $4.1 million and $1.8 million for the three months ended March 31, 2020 and 2019, respectively. Portions of these amounts are reflected as contributions to partners’ capital in the consolidated statements of equity and partners’ capital. Concentration of credit risk. Occidental was the only customer from which revenues exceeded 10% of consolidated revenues for all periods presented in the consolidated statements of operations.

Equity Investments

Equity Investments	3 Months Ended
	Mar. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	7. EQUITY INVESTMENTS The following table presents the equity-investments activity for the three months ended March 31, 2020 : thousands Balance at December 31, 2019 Equity income, net Contributions Distributions Distributions in excess of cumulative earnings (1) Balance at March 31, 2020 Fort Union $ (610 ) $ 155 $ — $ — $ — $ (455 ) White Cliffs 45,877 2,373 — (2,227 ) (382 ) 45,641 Rendezvous 32,964 78 — (564 ) (789 ) 31,689 Mont Belvieu JV 103,036 7,046 — (7,056 ) (919 ) 102,107 TEG 18,199 1,062 — (1,068 ) (1,147 ) 17,046 TEP 203,556 8,710 — (10,120 ) — 202,146 FRP 207,782 9,798 3,670 (11,185 ) (648 ) 209,417 Whitethorn LLC 161,665 10,242 278 (8,558 ) — 163,627 Cactus II 172,165 8,008 6,360 (7,608 ) — 178,925 Saddlehorn 112,855 6,738 — (7,254 ) — 112,339 Panola 21,783 438 — (438 ) (287 ) 21,496 Mi Vida 57,807 2,308 — (1,396 ) — 58,719 Ranch Westex 46,678 3,189 — (2,192 ) (705 ) 46,970 Red Bluff Express 101,960 1,202 652 (1,202 ) (175 ) 102,437 Total $ 1,285,717 $ 61,347 $ 10,960 $ (60,868 ) $ (5,052 ) $ 1,292,104 (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.

Property, Plant, and Equipment

Property, Plant, and Equipment	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment	8. PROPERTY, PLANT, AND EQUIPMENT A summary of the historical cost of property, plant, and equipment is as follows: thousands Estimated Useful Life March 31, December 31, Land n/a $ 9,495 $ 9,495 Gathering systems – pipelines 30 years 5,163,286 5,092,004 Gathering systems – compressors 15 years 2,006,896 1,929,377 Processing complexes and treating facilities 25 years 3,370,462 3,237,801 Transportation pipeline and equipment 6 to 45 years 171,111 173,572 Produced-water disposal systems 20 years 791,882 754,774 Assets under construction n/a 337,000 486,584 Other 3 to 40 years 695,225 672,064 Total property, plant, and equipment 12,545,357 12,355,671 Less accumulated depreciation 3,558,626 3,290,740 Net property, plant, and equipment $ 8,986,731 $ 9,064,931 The cost of property classified as “Assets under construction” is excluded from capitalized costs being depreciated. These amounts represent property that is not yet placed into productive service as of the respective balance sheet date. Long-lived asset impairments. During the three months ended March 31, 2020 , the Partnership recognized impairments of $155.8 million , primarily due to $145.1 million of impairments for assets located in Wyoming and Utah. These assets were impaired to estimated fair values of $91.0 million and estimated salvage value of $6.7 million . The Partnership assesses whether events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The fair value of assets with impairment triggers were measured using the income approach and Level-3 fair value inputs. The income approach was based on the Partnership’s projected future earnings before interest, taxes, depreciation, and amortization (“EBITDA”) and free cash flows, which requires significant assumptions including, among others, future throughput volumes based on current expectations of producer activity and operating costs. These impairments were triggered by reductions in estimated future cash flows resulting from lower forecasted producer throughput and lower commodity prices. The remaining impairments of $10.7 million were primarily at the DJ Basin complex due to cancellation of projects and impairments of rights-of-way. During the year ended December 31, 2019, the Partnership recognized impairments of $6.3 million , primarily at the DJ Basin complex due to impairments of rights-of-way and cancellation of projects. Potential future long-lived asset impairments. As of March 31, 2020, it is reasonably possible that prolonged low commodity prices, further commodity-price declines, and changes to producers’ drilling plans in response to lower prices could result in future long-lived asset impairments.

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	9. GOODWILL Goodwill is recorded when the purchase price of a business acquired exceeds the fair market value of the tangible and separately measurable intangible net assets. Goodwill also includes the allocated historic carrying value of midstream goodwill attributed to the Partnership’s assets previously acquired from Anadarko. The Partnership’s goodwill has been allocated to two reporting units: (i) gathering and processing and (ii) transportation. The Partnership evaluates goodwill for impairment annually, as of October 1, or more often as facts and circumstances warrant. An initial qualitative assessment is performed to determine the likelihood of whether goodwill is impaired and if deemed necessary based on this assessment, a quantitative assessment is then performed. If the quantitative assessment indicates that the carrying amount of the reporting unit, including goodwill, exceeds its fair value, a goodwill impairment is recorded for the amount by which the reporting unit’s carrying value exceeds its fair value. During the three months ended March 31, 2020, the Partnership performed an interim goodwill impairment test due to a significant decline in the trading price of the Partnership’s common units, triggered by the combined impacts from the global outbreak of COVID-19 and the oil-market disruption resulting from significantly lower global demand and corresponding oversupply of crude oil. The Partnership primarily used the market approach and Level-3 inputs to estimate the fair value of its two reporting units. The market approach was based on multiples of EBITDA and the Partnership’s projected future EBITDA. The EBITDA multiples were based on current and historic multiples for comparable midstream companies of similar size and business profit to the Partnership. The EBITDA projections require significant assumptions including, among others, future throughput volumes based on current expectations of producer activity and operating costs. The reasonableness of the market approach was tested against an income approach that was based on a discounted cash-flow analysis. Key assumptions in this analysis include the use of an appropriate discount rate, terminal-year multiples, and estimated future cash flows, including estimates of throughput, capital expenditures, operating, and general and administrative costs. The Partnership also reviewed the reasonableness of the total fair value of both reporting units to the market capitalization as of March 31, 2020, and the reasonableness of an implied acquisition premium. Impairment determinations involve significant assumptions and judgments, and differing assumptions regarding any of these inputs could have a significant effect on the valuations. As a result of the interim impairment test, the Partnership recognized a goodwill impairment of $441.0 million , which reduced the carrying amount of goodwill to zero for the gathering and processing reporting unit as of March 31, 2020. Goodwill allocated to the transportation reporting unit of $4.8 million as of March 31, 2020, was not impaired.

Components of Working Capital

Components of Working Capital	3 Months Ended
	Mar. 31, 2020
Components Of Working Capital [Abstract]
Components of Working Capital	10. COMPONENTS OF WORKING CAPITAL A summary of accounts receivable, net is as follows: The Partnership WES Operating thousands March 31, December 31, March 31, December 31, Trade receivables, net $ 254,314 $ 260,458 $ 246,918 $ 260,694 Other receivables, net 2,925 54 2,925 54 Total accounts receivable, net $ 257,239 $ 260,512 $ 249,843 $ 260,748 A summary of other current assets is as follows: The Partnership WES Operating thousands March 31, December 31, March 31, December 31, NGLs inventory $ 469 $ 906 $ 469 $ 906 Materials and supplies inventory 50,291 23,444 50,291 23,444 Imbalance receivables 6,683 4,690 6,683 4,690 Prepaid insurance 3,785 5,676 2,082 3,652 Contract assets 12,975 7,129 12,975 7,129 Other 6,824 93 6,824 93 Total other current assets $ 81,027 $ 41,938 $ 79,324 $ 39,914 A summary of accrued liabilities is as follows: The Partnership WES Operating thousands March 31, December 31, March 31, December 31, Accrued interest expense $ 82,818 $ 72,064 $ 82,818 $ 72,064 Short-term asset retirement obligations 29,633 22,472 29,633 22,472 Short-term remediation and reclamation obligations 3,528 3,528 3,528 3,528 Income taxes payable — 697 — 697 Contract liabilities 9,120 19,659 9,120 19,659 Other (1) 41,639 31,373 35,076 31,219 Total accrued liabilities $ 166,738 $ 149,793 $ 160,175 $ 149,639 (1) Includes amounts related to WES Operating’s interest-rate swap agreements as of March 31, 2020 , and December 31, 2019 (see Note 11 ).

Debt and Interest Expense

Debt and Interest Expense	3 Months Ended
	Mar. 31, 2020
Debt Instruments [Abstract]
Debt and Interest Expense	11. DEBT AND INTEREST EXPENSE WES Operating is the borrower for all outstanding debt and is expected to be the borrower for all future debt issuances. The following table presents the outstanding debt: March 31, 2020 December 31, 2019 thousands Principal Carrying Value Fair Value (1) Principal Carrying Value Fair Value (1) Short-term debt Finance lease liabilities (2) $ 11,184 $ 11,184 $ 11,184 $ 7,873 $ 7,873 $ 7,873 Total short-term debt $ 11,184 $ 11,184 $ 11,184 $ 7,873 $ 7,873 $ 7,873 Long-term debt 5.375% Senior Notes due 2021 $ 438,631 $ 437,300 $ 352,437 $ 500,000 $ 498,168 $ 515,042 4.000% Senior Notes due 2022 631,369 630,790 408,183 670,000 669,322 689,784 Floating-Rate Senior Notes due 2023 300,000 298,118 158,400 — — — 3.100% Senior Notes due 2025 1,000,000 991,713 509,618 — — — 3.950% Senior Notes due 2025 500,000 494,086 254,103 500,000 493,830 504,968 4.650% Senior Notes due 2026 500,000 496,323 258,950 500,000 496,197 513,393 4.500% Senior Notes due 2028 400,000 395,236 191,693 400,000 395,113 390,920 4.750% Senior Notes due 2028 400,000 396,280 189,498 400,000 396,190 400,962 4.050% Senior Notes due 2030 1,200,000 1,188,718 500,911 — — — 5.450% Senior Notes due 2044 600,000 593,501 224,905 600,000 593,470 533,710 5.300% Senior Notes due 2048 700,000 686,893 277,851 700,000 686,843 610,841 5.500% Senior Notes due 2048 350,000 342,459 132,332 350,000 342,432 310,198 5.250% Senior Notes due 2050 1,000,000 983,354 413,544 — — — RCF 125,000 125,000 125,000 380,000 380,000 380,000 Term loan facility — — — 3,000,000 3,000,000 3,000,000 Finance lease liabilities 28,990 28,990 28,990 — — — Total long-term debt $ 8,173,990 $ 8,088,761 $ 4,026,415 $ 8,000,000 $ 7,951,565 $ 7,849,818 (1) Fair value is measured using the market approach and Level-2 fair value inputs. (2) Includes related-party amounts of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively. 11. DEBT AND INTEREST EXPENSE (CONTINUED) Debt activity. The following table presents the debt activity for the three months ended March 31, 2020 : thousands Carrying Value Balance at December 31, 2019 $ 7,959,438 RCF borrowings 125,000 Issuance of Floating-Rate Senior Notes due 2023 300,000 Issuance of 3.100% Senior Notes due 2025 1,000,000 Issuance of 4.050% Senior Notes due 2030 1,200,000 Issuance of 5.250% Senior Notes due 2050 1,000,000 Finance lease liabilities 32,300 Repayments of RCF borrowings (380,000 ) Repayment of Term loan facility borrowings (3,000,000 ) Repayment of 5.375% Senior Notes due 2021 (61,369 ) Repayment of 4.000% Senior Notes due 2022 (38,631 ) Other (36,793 ) Balance at March 31, 2020 $ 8,099,945 WES Operating Senior Notes. In January 2020, WES Operating issued the following notes: • 3.100% Senior Notes due 2025, 4.050% Senior Notes due 2030, and 5.250% Senior Notes due 2050, offered to the public at prices of 99.962% , 99.900% , and 99.442% , respectively, of the face amount (collectively referred to as the “Senior Notes”). Including the effects of the issuance and underwriting discounts, the effective interest rates of the Senior Notes due 2025, 2030, and 2050, are 3.287% , 4.168% , and 5.362% , respectively. Interest is paid on each such series semi-annually on February 1 and August 1 of each year, beginning August 1, 2020; and • Floating-Rate Senior Notes due 2023 (the “Floating-Rate Notes”). As of March 31, 2020 , the interest rate on the Floating-Rate Notes was 2.69% . Interest is paid quarterly in arrears on January 13, April 13, July 13, and October 13 of each year, beginning April 13, 2020. Interest will accrue from January 13, 2020 at a benchmark rate (which will initially be a three-month London Interbank Offered Rate) on the interest determination date plus 0.85% . Net proceeds from the Senior Notes and Floating-Rate Notes were used to repay the $3.0 billion outstanding borrowings under the Term loan facility and outstanding amounts under the RCF, and for general partnership purposes. The interest payable on each of the Senior Notes and Floating-Rate Notes are subject to adjustment from time to time if the credit rating assigned to such notes declines below certain specified levels or if credit-rating downgrades are subsequently followed by credit-rating upgrades. In March 2020, Fitch Ratings (“Fitch”) and Standard and Poor’s (“S&P”) downgraded WES Operating’s long-term debt from “BBB-” to “BB+.” As a result of these downgrades, the annualized borrowing costs will increase by $17.5 million . During the first quarter of 2020, WES Operating purchased and retired $61.4 million of the 5.375% Senior Notes due 2021 and $38.6 million of the 4.000% Senior Notes due 2022 via open-market repurchases. For the three months ended March 31, 2020 , a gain of $9.6 million was recognized for the early retirement of these notes. At March 31, 2020 , WES Operating was in compliance with all covenants under the relevant governing indentures. WGP RCF. The WGP RCF, which previously was available to purchase WES Operating common units and for general partnership purposes, matured in March 2019 and the $28.0 million of outstanding borrowings were repaid. 11. DEBT AND INTEREST EXPENSE (CONTINUED) Revolving credit facility. In December 2019, WES Operating entered into an amendment to the RCF, which is expandable to a maximum of $2.5 billion , to, among other things, exercise the final one-year extension option to extend the maturity date of the RCF from February 2024 to February 2025, for each extending lender. The maturity date with respect to each non-extending lender, whose commitments represent $100.0 million out of $2.0 billion of total commitments from all lenders, remains February 2024. See Note 1 . As of March 31, 2020 , there were $125.0 million of outstanding borrowings and $6.5 million of outstanding letters of credit, resulting in $1.9 billion of available borrowing capacity under the RCF. As of March 31, 2020 and 2019 , the interest rate on any outstanding RCF borrowings was 2.13% and 3.79% , respectively. The facility-fee rate was 0.20% at March 31, 2020 and 2019 . At March 31, 2020 , WES Operating was in compliance with all covenants under the RCF. As a result of credit-rating downgrades received from Fitch and S&P (see WES Operating Senior Notes above), beginning in the second quarter of 2020, the interest rate on outstanding RCF borrowings will increase by 0.20% and the RCF facility-fee rate will increase by 0.05% , from 0.20% to 0.25% . Term loan facility. In December 2018, WES Operating entered into the Term loan facility, the proceeds from which were used to fund substantially all of the cash portion of the consideration under the Merger Agreement and the payment of related transaction costs (see Note 1 ). As of March 31, 2019 , the interest rate on the outstanding borrowings was 3.87% . In January 2020, WES Operating repaid the outstanding borrowings with proceeds from the issuance of the Senior Notes and Floating-Rate Notes and terminated the Term loan facility (see WES Operating Senior Notes above). For the three months ended March 31, 2020 , a loss of $2.3 million was recognized for the early termination of the Term loan facility. Finance lease liabilities. The Partnership has subleased equipment from Occidental via finance leases extending through April 2020, with future lease payments of $2.6 million as of March 31, 2020 . During the first quarter of 2020, the Partnership entered into finance leases with third parties for equipment and vehicles extending through 2029, with future lease payments of $43.5 million as of March 31, 2020 . APCWH Note Payable. In June 2017, in connection with funding the construction of the APC water systems that were acquired as part of the AMA acquisition, APCWH entered into an eight-year note payable agreement with Anadarko. This note payable had a maximum borrowing limit of $500.0 million , including accrued interest. The APCWH Note Payable was repaid at Merger completion. See Note 1 . Interest-rate swaps. In December 2018 and March 2019, WES Operating entered into interest-rate swap agreements with an aggregate notional principal amount of $750.0 million and $375.0 million , respectively, to manage interest-rate risk associated with anticipated debt issuances. In November and December 2019, WES Operating entered into additional interest-rate swap agreements with an aggregate notional principal amount of $1,125.0 million , effectively offsetting the swap agreements entered into in December 2018 and March 2019. In December 2019, all outstanding interest-rate swap agreements were cash-settled. As part of the settlement, WES Operating made cash payments of $107.7 million and recorded an accrued liability of $25.6 million to be paid quarterly in 2020. These cash payments were classified as cash flows from operating activities in the consolidated statements of cash flows. The Partnership did not apply hedge accounting and, therefore, gains and losses associated with the interest-rate swap agreements were recognized in earnings. For the three months ended March 31, 2019 , a non-cash loss of $35.6 million was recognized, which is included in Other income (expense), net in the consolidated statements of operations. 11. DEBT AND INTEREST EXPENSE (CONTINUED) Interest expense. The following table summarizes the amounts included in interest expense: Three Months Ended thousands 2020 2019 Third parties Long-term and short-term debt $ (89,769 ) $ (67,096 ) Finance lease liabilities (405 ) — Amortization of debt issuance costs and commitment fees (3,127 ) (3,152 ) Capitalized interest 4,758 6,205 Total interest expense – third parties (88,543 ) (64,043 ) Related parties APCWH Note Payable — (1,833 ) Finance lease liabilities (43 ) — Total interest expense – related parties (43 ) (1,833 ) Interest expense $ (88,586 ) $ (65,876 )

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. COMMITMENTS AND CONTINGENCIES Litigation and legal proceedings. 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 for which the final disposition 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, and those of its unconsolidated related parties, the majority of which is expected to be paid in the next twelve months. These commitments primarily relate to construction and expansion projects at the West Texas and DJ Basin complexes, DBM water systems, and DBM oil system.

Description of Business and B_2

Description of Business and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Consolidation policy	Noncontrolling interests. For periods subsequent to Merger completion, the Partnership’s noncontrolling interests in the consolidated financial statements consist of (i) the 25% third-party interest in Chipeta and (ii) the 2.0% Occidental subsidiary-owned limited partner interest in WES Operating. For periods prior to Merger completion, the Partnership’s noncontrolling interests in the consolidated financial statements consisted of (i) the 25% third-party interest in Chipeta, (ii) the publicly held limited partner interests in WES Operating, (iii) the common units issued by WES Operating to subsidiaries of Anadarko as part of the consideration paid for prior-period acquisitions from Anadarko, and (iv) the Class C units issued by WES Operating to a subsidiary of Anadarko as part of the funding for the acquisition of DBM. For all periods presented, WES Operating’s noncontrolling interest in the consolidated financial statements consists of the 25% third-party interest in Chipeta. See Note 5 . When WES Operating issues equity, the carrying amount of the noncontrolling interest reported by the Partnership is adjusted to reflect the noncontrolling ownership interest in WES Operating. The resulting impact of such noncontrolling interest adjustment on the Partnership’s interest in WES Operating is reflected as an adjustment to the Partnership’s partners’ capital. Basis of presentation. 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, including WES Operating and WES Operating GP. All significant intercompany transactions have been eliminated. The following table outlines the ownership interests and the accounting method of consolidation used in the consolidated financial statements for entities not wholly owned: Percentage Interest Full consolidation Chipeta (1) 75.00 % Proportionate consolidation (2) Springfield system 50.10 % Marcellus Interest systems 33.75 % Equity investments (3) Mi Vida 50.00 % Ranch Westex 50.00 % FRP 33.33 % Red Bluff Express 30.00 % Mont Belvieu JV 25.00 % Rendezvous 22.00 % TEP 20.00 % TEG 20.00 % Whitethorn LLC 20.00 % Saddlehorn 20.00 % Cactus II 15.00 % Panola 15.00 % Fort Union 14.81 % White Cliffs 10.00 % (1) The 25% third-party interest in Chipeta Processing LLC (“Chipeta”) is reflected within noncontrolling interests in the consolidated financial statements. See Noncontrolling interests below. (2) The Partnership proportionately consolidates its associated share of the assets, liabilities, revenues, and expenses attributable to these assets. (3) Investments in non-controlled entities over which the Partnership exercises significant influence are accounted for under the equity method of accounting. “Equity-investment throughput” refers to the Partnership’s share of average throughput for these investments. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) The consolidated financial results of WES Operating are included in the Partnership’s consolidated financial statements. Throughout these notes to consolidated financial statements, and to the extent material, any differences between the consolidated financial results of the Partnership and WES Operating are discussed separately. The Partnership’s consolidated financial statements differ from those of WES Operating primarily as a result of (i) the presentation of noncontrolling interest ownership (see Noncontrolling interests below and Note 5 ), (ii) the elimination of WES Operating GP’s investment in WES Operating with WES Operating GP’s underlying capital account, (iii) the general and administrative expenses incurred by the Partnership, which are separate from, and in addition to, those incurred by WES Operating, (iv) the inclusion of the impact of Partnership equity balances and Partnership distributions, and (v) the senior secured revolving credit facility (“WGP RCF”) until its repayment in March 2019. See Note 11 .
Business combinations policy	Presentation of the Partnership’s assets. The Partnership’s assets include assets owned and ownership interests accounted for by the Partnership under the equity method of accounting, through its 98.0% partnership interest in WES Operating as of March 31, 2020 (see Note 7 ). The Partnership also owns and controls the entire non-economic general partner interest in WES Operating GP, and the Partnership’s general partner is owned by Occidental.
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 reasonable methods. Changes in facts and circumstances or additional information may result in revised estimates and actual results may differ from these estimates. Effects on the business, financial condition, and results of operations resulting from revisions to estimates are recognized when the facts that give rise to the revisions become known. The information included herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the consolidated financial statements, and certain prior-period amounts have been reclassified to conform to the current-year presentation.
Segments policy	Segments.
Equity-based compensation policy	Equity-based compensation. On February 10, 2020, the Board of Directors approved awards of phantom units (the “Awards”) to the Partnership’s executive officers under the Western Gas Equity Partners, LP 2012 Long-Term Incentive Plan. The Awards include (i) an award of time-vested phantom units that vest ratably over a three-year period (“Time-Based Awards”), (ii) a market award that vests after a three-year performance period based on the Partnership’s relative total unitholder return as compared to a group of peer companies (“TUR Awards”), and (iii) a performance award that vests based on the Partnership’s average return on assets over a three-year performance period (“ROA Awards”). At vesting, the value of the TUR Awards and the ROA Awards will be determined in accordance with the terms of the respective Award Agreements that provide for payout percentages ranging from 0% to 200% based on results achieved over the applicable performance period. At vesting, the Awards generally will be settled in Partnership common units. Prior to vesting, the Awards pay in-kind distributions in the form of Partnership common units. In addition, phantom units are awarded under the Western Gas Equity Partners, LP 2012 Long-Term Incentive Plan to non-executive employees of the Partnership from time to time. These time-vested phantom units vest ratably over a three-year period and, prior to vesting, pay distribution equivalents in cash. The Partnership accounts for these equity-classified awards at fair value. The equity-based compensation expense attributable to these awards is amortized over a three-year service period using the straight-line method. Expense is recognized based on the grant-date fair value and recorded, net of any forfeitures, as General and administrative expense in the consolidated statements of operations. The fair value of the Time-based Awards, ROA Awards, and non-executive awards is based on the observable market price of the Partnership’s units on the grant date of the award. The fair value of the TUR Awards is determined using a Monte Carlo simulation.
Defined-contribution plan policy	Defined-contribution plan. Beginning in the first quarter of 2020, employees of the Partnership are eligible to participate in the Western Midstream Savings Plan, a defined-contribution benefit plan maintained by the Partnership. All regular employees may participate in the plan by making elective contributions that are matched by the Partnership, subject to certain limitations. The Partnership also makes other contributions based on plan guidelines. The Partnership recognized expense related to the plan of $0.4 million for the three months ended March 31, 2020, recorded as General and administrative expense in the consolidated statements of operations.
New accounting standards policy	Recently adopted accounting standards. Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326) significantly changes the accounting and disclosure requirements related to credit losses on financial assets. Under the new standard, entities are now required to estimate lifetime expected credit losses for trade receivables, loans, and other financial instruments as of the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts, resulting in earlier recognition of credit losses. There was no impact to the consolidated financial statements with the Partnership’s adoption of the standard on January 1, 2020. The Partnership has implemented the necessary changes to its processes and controls to support accounting and disclosure requirements under this ASU. Accounts receivable and contract assets. Accounts receivable represent contractual rights for services performed, with, on average, 30-day payment terms. Contract assets primarily relate to accrued deficiency fees and revenue accrued but not yet billed under cost-of-service contracts. As of March 31, 2020, there have been no negative indications regarding the collectability of these receivables as it relates to impacts from the global outbreak of the coronavirus (“COVID-19”) and the oil-market disruption resulting from significantly lower global demand and corresponding oversupply of crude oil. The Partnership will continue to monitor the credit quality of its customer base and assess collectability of these assets as appropriate. 1. DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (CONTINUED) Notes receivable. In May 2008, WES Operating 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 “Anadarko note receivable”). Following Occidental’s acquisition by merger of Anadarko in August 2019, Occidental became the ultimate counterparty. As of March 31, 2020, the Partnership assessed the recoverability of the Anadarko note receivable under the loss-given-default method using historical data from internal and external sources, current market conditions, and reasonable and supportable forecasted information. The loss-given-default approach was based on applicable probability of default percentages for similar debt instruments and the fair value of the Anadarko note receivable, which reflects an analysis of Occidental’s yield based on quoted market yields of similar Occidental debt instruments. As of March 31, 2020, the Partnership recognized an allowance for expected credit losses of $2.1 million related to the note receivable. See Note 6 .
Derivatives policy	The Partnership did not apply hedge accounting and, therefore, gains and losses associated with the interest-rate swap agreements were recognized in earnings. For the three months ended March 31, 2019 , a non-cash loss of $35.6 million was recognized, which is included in Other income (expense), net in the consolidated statements of operations.
Net income (loss) per common unit policy	Partnership’s net income (loss) per common unit. Following the transactions contemplated by the Exchange Agreement, the common and general partner unitholders’ allocation of net income (loss) attributable to the Partnership was equal to their cash distributions plus their respective allocations of undistributed earnings or losses using the two-class method. Specifically, net income equal to the amount of available cash (as defined by the partnership agreement) was allocated to the common and general partner unitholders consistent with actual cash distributions and capital account allocations. Undistributed earnings (net income in excess of distributions) or undistributed losses (available cash in excess of net income (loss)) were then allocated to the common and general partner unitholders in accordance with their weighted-average ownership percentage during each period. The Partnership’s basic net income (loss) per common unit is calculated by dividing the limited partners’ interest in net income (loss) by the weighted-average number of common units outstanding during the period. Net income (loss) attributable to assets acquired from Anadarko for periods prior to the acquisition of such assets was not allocated to the limited partners when calculating net income (loss) per common unit. WES Operating’s net income (loss) per common unit. For periods subsequent to the closing of the Merger, net income (loss) per common unit for WES Operating is not calculated as it no longer has any publicly traded units outstanding.
Goodwill policy	Goodwill is recorded when the purchase price of a business acquired exceeds the fair market value of the tangible and separately measurable intangible net assets. Goodwill also includes the allocated historic carrying value of midstream goodwill attributed to the Partnership’s assets previously acquired from Anadarko. The Partnership’s goodwill has been allocated to two reporting units: (i) gathering and processing and (ii) transportation. The Partnership evaluates goodwill for impairment annually, as of October 1, or more often as facts and circumstances warrant. An initial qualitative assessment is performed to determine the likelihood of whether goodwill is impaired and if deemed necessary based on this assessment, a quantitative assessment is then performed. If the quantitative assessment indicates that the carrying amount of the reporting unit, including goodwill, exceeds its fair value, a goodwill impairment is recorded for the amount by which the reporting unit’s carrying value exceeds its fair value.

Description of Business and B_3

Description of Business and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Assets and Investments Table	As of March 31, 2020 , the Partnership’s assets and investments consisted of the following: Wholly Owned and Operated Operated Interests Non-Operated Interests Equity Interests Gathering systems (1) 17 2 3 2 Treating facilities 38 3 — 3 Natural-gas processing plants/trains 26 3 — 5 NGLs pipelines 2 — — 4 Natural-gas pipelines 5 — — 1 Crude-oil pipelines 3 1 — 3 (1) Includes the DBM water systems.
Ownership Interests and Method of Consolidation Table	The following table outlines the ownership interests and the accounting method of consolidation used in the consolidated financial statements for entities not wholly owned: Percentage Interest Full consolidation Chipeta (1) 75.00 % Proportionate consolidation (2) Springfield system 50.10 % Marcellus Interest systems 33.75 % Equity investments (3) Mi Vida 50.00 % Ranch Westex 50.00 % FRP 33.33 % Red Bluff Express 30.00 % Mont Belvieu JV 25.00 % Rendezvous 22.00 % TEP 20.00 % TEG 20.00 % Whitethorn LLC 20.00 % Saddlehorn 20.00 % Cactus II 15.00 % Panola 15.00 % Fort Union 14.81 % White Cliffs 10.00 % (1) The 25% third-party interest in Chipeta Processing LLC (“Chipeta”) is reflected within noncontrolling interests in the consolidated financial statements. See Noncontrolling interests below. (2) The Partnership proportionately consolidates its associated share of the assets, liabilities, revenues, and expenses attributable to these assets. (3) Investments in non-controlled entities over which the Partnership exercises significant influence are accounted for under the equity method of accounting. “Equity-investment throughput” refers to the Partnership’s share of average throughput for these investments.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Summary of Revenue from Contracts with Customers Table	The following table summarizes revenue from contracts with customers: Three Months Ended thousands 2020 2019 Revenue from customers Service revenues – fee based $ 641,921 $ 579,974 Service revenues – product based 15,921 19,379 Product sales 56,649 72,800 Total revenue from customers 714,491 672,153 Revenue from other than customers Lease revenue (1) 59,475 — Net gains (losses) on commodity-price swap agreements — (667 ) Other 347 397 Total revenues and other $ 774,313 $ 671,883 (1) For the three months ended March 31, 2020 , includes fixed- and variable-lease revenue from an operating and maintenance agreement entered into with Occidental. See Operating lease within Note 6 .
Contract Assets and Liabilities Activity Tables	The following table summarizes current-period activity related to contract assets from contracts with customers: thousands Balance at December 31, 2019 $ 67,357 Additional estimated revenues recognized 5,365 Balance at March 31, 2020 $ 72,722 Contract assets at March 31, 2020 Other current assets $ 12,975 Other assets 59,747 Total contract assets from contracts with customers $ 72,722 thousands Balance at December 31, 2019 $ 222,274 Cash received or receivable, excluding revenues recognized during the period 11,203 Revenues recognized that were included in the contract liability balance at the beginning of the period (8,893 ) Balance at March 31, 2020 $ 224,584 Contract liabilities at March 31, 2020 Accrued liabilities $ 9,120 Other liabilities 215,464 Total contract liabilities from contracts with customers $ 224,584
Expected Revenue Recognition from Satisfaction of Performance Obligations Table	Therefore, the following table represents only a portion of expected future revenues from existing contracts as most future revenues from customers are dependent on future variable customer volumes and, in some cases, variable commodity prices for those volumes. thousands Remainder of 2020 $ 572,077 2021 779,098 2022 1,035,119 2023 978,409 2024 948,700 Thereafter 3,547,074 Total $ 7,860,477

Partnership Distributions (Tabl

Partnership Distributions (Tables)	3 Months Ended
	Mar. 31, 2020
Distributions Made to Members or Limited Partners [Abstract]
Cash Distributions Tables	The Board of Directors declared the following cash distributions to the Partnership’s unitholders for the periods presented: thousands except per-unit amounts Quarters Ended Total Quarterly Total Quarterly Distribution 2019 March 31 $ 0.61000 $ 276,324 May 2019 June 30 0.61800 279,959 August 2019 September 30 0.62000 280,880 November 2019 December 31 0.62200 281,786 February 2020 2020 March 31 (1) $ 0.31100 $ 140,893 May 2020 (1) The Board of Directors declared a cash distribution to the Partnership’s unitholders for the first quarter of 2020 of $0.31100 per unit, or $140.9 million in aggregate. The cash distribution is payable on May 14, 2020 to unitholders of record at the close of business on May 1, 2020 , including the general partner units that were issued on December 31, 2019 (see Note 1 ). WES Operating made the following cash distributions to its limited partners for the periods presented: thousands Quarters Ended Total Quarterly 2019 March 31 $ 283,271 June 30 288,083 September 30 289,676 December 31 290,314 2020 March 31 $ 143,404

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2020
Related Party Transaction [Line Items]
Related-Party Transactions Tables	The following table summarizes material related-party transactions included in the Partnership’s consolidated financial statements: Three Months Ended thousands 2020 2019 Revenues and other $ 482,385 $ 378,437 Equity income, net – related parties 61,347 57,992 Operating expenses Cost of product 77,903 56,172 Operation and maintenance 32,841 39,141 General and administrative (1) 21,855 18,894 Total operating expenses 132,599 114,207 Interest income (2) 4,225 4,225 Interest expense (3) 43 1,833 APCWH Note Payable borrowings — 11,000 Repayment of APCWH Note Payable — 439,595 Distributions to Partnership unitholders (4) 150,609 102,654 Distributions to WES Operating unitholders (5) 5,807 2,543 Above-market component of swap agreements with Anadarko — 7,407 (1) Includes amounts charged by Occidental pursuant to the shared services agreements (see Shared services agreements within this Note 6 ) . Also see Incentive Plans within this Note 6 . (2) Represents interest income recognized on the Anadarko note receivable. (3) Includes amounts related to finance leases for the three months ended March 31, 2020 , and the APCWH Note Payable for the three months ended March 31, 2019 (see Note 11 ) . (4) Represents distributions paid to Occidental pursuant to the partnership agreement of the Partnership (see Note 4 and Note 5 ). (5) Represents distributions paid to certain subsidiaries of Occidental pursuant to WES Operating’s partnership agreement (see Note 4 and Note 5 ).
WES Operating [Member]
Related Party Transaction [Line Items]
Related-Party Transactions Tables	The following table summarizes material related-party transactions for WES Operating (which are included in the Partnership’s consolidated financial statements) to the extent the amounts differ from the Partnership’s consolidated financial statements: Three Months Ended thousands 2020 2019 General and administrative (1) $ 21,738 $ 18,498 Distributions to WES Operating unitholders (2) 290,314 164,902 (1) Includes amounts charged by Occidental pursuant to the shared services agreements (see Shared services agreements within this Note 6 ). Also see Incentive Plans within this Note 6 . (2) Represents distributions paid to the Partnership and certain subsidiaries of Occidental pursuant to WES Operating’s partnership agreement (see Note 4 and Note 5 ). For the three months ended March 31, 2019 , includes distributions to the Partnership and a subsidiary of Occidental related to the repayment of the WGP RCF (see Note 11 ).

Equity Investments (Tables)

Equity Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments Table	The following table presents the equity-investments activity for the three months ended March 31, 2020 : thousands Balance at December 31, 2019 Equity income, net Contributions Distributions Distributions in excess of cumulative earnings (1) Balance at March 31, 2020 Fort Union $ (610 ) $ 155 $ — $ — $ — $ (455 ) White Cliffs 45,877 2,373 — (2,227 ) (382 ) 45,641 Rendezvous 32,964 78 — (564 ) (789 ) 31,689 Mont Belvieu JV 103,036 7,046 — (7,056 ) (919 ) 102,107 TEG 18,199 1,062 — (1,068 ) (1,147 ) 17,046 TEP 203,556 8,710 — (10,120 ) — 202,146 FRP 207,782 9,798 3,670 (11,185 ) (648 ) 209,417 Whitethorn LLC 161,665 10,242 278 (8,558 ) — 163,627 Cactus II 172,165 8,008 6,360 (7,608 ) — 178,925 Saddlehorn 112,855 6,738 — (7,254 ) — 112,339 Panola 21,783 438 — (438 ) (287 ) 21,496 Mi Vida 57,807 2,308 — (1,396 ) — 58,719 Ranch Westex 46,678 3,189 — (2,192 ) (705 ) 46,970 Red Bluff Express 101,960 1,202 652 (1,202 ) (175 ) 102,437 Total $ 1,285,717 $ 61,347 $ 10,960 $ (60,868 ) $ (5,052 ) $ 1,292,104 (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.

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	3 Months Ended
	Mar. 31, 2020
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, December 31, Land n/a $ 9,495 $ 9,495 Gathering systems – pipelines 30 years 5,163,286 5,092,004 Gathering systems – compressors 15 years 2,006,896 1,929,377 Processing complexes and treating facilities 25 years 3,370,462 3,237,801 Transportation pipeline and equipment 6 to 45 years 171,111 173,572 Produced-water disposal systems 20 years 791,882 754,774 Assets under construction n/a 337,000 486,584 Other 3 to 40 years 695,225 672,064 Total property, plant, and equipment 12,545,357 12,355,671 Less accumulated depreciation 3,558,626 3,290,740 Net property, plant, and equipment $ 8,986,731 $ 9,064,931

Components of Working Capital (

Components of Working Capital (Tables)	3 Months Ended
	Mar. 31, 2020
Components Of Working Capital [Abstract]
Accounts Receivable, Net Table	A summary of accounts receivable, net is as follows: The Partnership WES Operating thousands March 31, December 31, March 31, December 31, Trade receivables, net $ 254,314 $ 260,458 $ 246,918 $ 260,694 Other receivables, net 2,925 54 2,925 54 Total accounts receivable, net $ 257,239 $ 260,512 $ 249,843 $ 260,748
Other Current Assets Table	A summary of other current assets is as follows: The Partnership WES Operating thousands March 31, December 31, March 31, December 31, NGLs inventory $ 469 $ 906 $ 469 $ 906 Materials and supplies inventory 50,291 23,444 50,291 23,444 Imbalance receivables 6,683 4,690 6,683 4,690 Prepaid insurance 3,785 5,676 2,082 3,652 Contract assets 12,975 7,129 12,975 7,129 Other 6,824 93 6,824 93 Total other current assets $ 81,027 $ 41,938 $ 79,324 $ 39,914
Accrued Liabilities Table	A summary of accrued liabilities is as follows: The Partnership WES Operating thousands March 31, December 31, March 31, December 31, Accrued interest expense $ 82,818 $ 72,064 $ 82,818 $ 72,064 Short-term asset retirement obligations 29,633 22,472 29,633 22,472 Short-term remediation and reclamation obligations 3,528 3,528 3,528 3,528 Income taxes payable — 697 — 697 Contract liabilities 9,120 19,659 9,120 19,659 Other (1) 41,639 31,373 35,076 31,219 Total accrued liabilities $ 166,738 $ 149,793 $ 160,175 $ 149,639 (1) Includes amounts related to WES Operating’s interest-rate swap agreements as of March 31, 2020 , and December 31, 2019 (see Note 11 ).

Debt and Interest Expense (Tabl

Debt and Interest Expense (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Instruments [Abstract]
Debt Outstanding and Debt Activity Tables	The following table presents the outstanding debt: March 31, 2020 December 31, 2019 thousands Principal Carrying Value Fair Value (1) Principal Carrying Value Fair Value (1) Short-term debt Finance lease liabilities (2) $ 11,184 $ 11,184 $ 11,184 $ 7,873 $ 7,873 $ 7,873 Total short-term debt $ 11,184 $ 11,184 $ 11,184 $ 7,873 $ 7,873 $ 7,873 Long-term debt 5.375% Senior Notes due 2021 $ 438,631 $ 437,300 $ 352,437 $ 500,000 $ 498,168 $ 515,042 4.000% Senior Notes due 2022 631,369 630,790 408,183 670,000 669,322 689,784 Floating-Rate Senior Notes due 2023 300,000 298,118 158,400 — — — 3.100% Senior Notes due 2025 1,000,000 991,713 509,618 — — — 3.950% Senior Notes due 2025 500,000 494,086 254,103 500,000 493,830 504,968 4.650% Senior Notes due 2026 500,000 496,323 258,950 500,000 496,197 513,393 4.500% Senior Notes due 2028 400,000 395,236 191,693 400,000 395,113 390,920 4.750% Senior Notes due 2028 400,000 396,280 189,498 400,000 396,190 400,962 4.050% Senior Notes due 2030 1,200,000 1,188,718 500,911 — — — 5.450% Senior Notes due 2044 600,000 593,501 224,905 600,000 593,470 533,710 5.300% Senior Notes due 2048 700,000 686,893 277,851 700,000 686,843 610,841 5.500% Senior Notes due 2048 350,000 342,459 132,332 350,000 342,432 310,198 5.250% Senior Notes due 2050 1,000,000 983,354 413,544 — — — RCF 125,000 125,000 125,000 380,000 380,000 380,000 Term loan facility — — — 3,000,000 3,000,000 3,000,000 Finance lease liabilities 28,990 28,990 28,990 — — — Total long-term debt $ 8,173,990 $ 8,088,761 $ 4,026,415 $ 8,000,000 $ 7,951,565 $ 7,849,818 (1) Fair value is measured using the market approach and Level-2 fair value inputs. (2) Includes related-party amounts of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively. 11. DEBT AND INTEREST EXPENSE (CONTINUED) Debt activity. The following table presents the debt activity for the three months ended March 31, 2020 : thousands Carrying Value Balance at December 31, 2019 $ 7,959,438 RCF borrowings 125,000 Issuance of Floating-Rate Senior Notes due 2023 300,000 Issuance of 3.100% Senior Notes due 2025 1,000,000 Issuance of 4.050% Senior Notes due 2030 1,200,000 Issuance of 5.250% Senior Notes due 2050 1,000,000 Finance lease liabilities 32,300 Repayments of RCF borrowings (380,000 ) Repayment of Term loan facility borrowings (3,000,000 ) Repayment of 5.375% Senior Notes due 2021 (61,369 ) Repayment of 4.000% Senior Notes due 2022 (38,631 ) Other (36,793 ) Balance at March 31, 2020 $ 8,099,945
Interest Expense Table	The following table summarizes the amounts included in interest expense: Three Months Ended thousands 2020 2019 Third parties Long-term and short-term debt $ (89,769 ) $ (67,096 ) Finance lease liabilities (405 ) — Amortization of debt issuance costs and commitment fees (3,127 ) (3,152 ) Capitalized interest 4,758 6,205 Total interest expense – third parties (88,543 ) (64,043 ) Related parties APCWH Note Payable — (1,833 ) Finance lease liabilities (43 ) — Total interest expense – related parties (43 ) (1,833 ) Interest expense $ (88,586 ) $ (65,876 )

Description of Business and B_4

Description of Business and Basis of Presentation - Assets and Investments Table (Details)	Mar. 31, 2020unit
Wholly Owned and Operated [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	17
Wholly Owned and Operated [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	38
Wholly Owned and Operated [Member] | Natural-Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	26
Wholly Owned and Operated [Member] | Natural-Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	2
Wholly Owned and Operated [Member] | Natural-Gas Pipelines [Member]
Assets [Line Items]
Assets, number of units	5
Wholly Owned and Operated [Member] | Crude-Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	3
Operated Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2
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	3
Operated Interests [Member] | Crude-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
Equity Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2
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	5
Equity Interests [Member] | Natural-Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	4
Equity Interests [Member] | Natural-Gas Pipelines [Member]
Assets [Line Items]
Assets, number of units	1
Equity Interests [Member] | Crude-Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	3

Description of Business and B_5

Description of Business and Basis of Presentation - Ownership Interests and Method of Consolidation Table (Details)	3 Months Ended
	Mar. 31, 2020
Chipeta [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Ownership interest by noncontrolling interest owner	25.00%
Full Consolidation [Member] | Chipeta [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	75.00%
Proportionate Consolidation [Member] | Springfield System [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	50.10%
Proportionate Consolidation [Member] | Marcellus Interest Systems [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Percentage ownership interest	33.75%
Equity Investments [Member] | Mi Vida [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	50.00%
Equity Investments [Member] | Ranch Westex [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	50.00%
Equity Investments [Member] | Front Range Pipeline [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	33.33%
Equity Investments [Member] | Red Bluff Express [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	30.00%
Equity Investments [Member] | Mont Belvieu JV [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	25.00%
Equity Investments [Member] | Rendezvous [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	22.00%
Equity Investments [Member] | Texas Express Pipeline [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	20.00%
Equity Investments [Member] | Texas Express Gathering [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	20.00%
Equity Investments [Member] | Whitethorn LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	20.00%
Equity Investments [Member] | Saddlehorn [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	20.00%
Equity Investments [Member] | Cactus II [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	15.00%
Equity Investments [Member] | Panola [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	15.00%
Equity Investments [Member] | Fort Union [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	14.81%
Equity Investments [Member] | White Cliffs [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Equity investment ownership percentage	10.00%

Description of Business and B_6

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($)	Dec. 31, 2019	May 31, 2008	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2018	Jul. 01, 2019	Feb. 28, 2019
Common units outstanding	443,971,409		443,971,409
Revenues and other			$ 774,313,000	$ 671,883,000
Defined-contribution plan expense			$ 400,000
Maximum [Member]
Equity-based compensation - payout percentage			200.00%
Minimum [Member]
Equity-based compensation - payout percentage			0.00%
Executive Long-Term Incentive Plans [Member]
Units vesting period			3 years
Non-Executive Long-Term Incentive Plans [Member]
Units vesting period			3 years
Affiliates [Member]
Revenues and other			$ 482,385,000	378,437,000
Note receivable - Anadarko		$ 260,000,000
Fixed annual rate for note receivable bearing interest		6.50%
Allowance for expected credit loss			2,100,000
Affiliates [Member] | Product Sales [Member]
Revenues and other			$ 31,624,000	50,443,000
Affiliates [Member] | Product Sales [Member] | Kitty Draw and Third Creek Gathering Systems [Member]
Revenues and other				5,500,000	$ (10,900,000)
WES Operating [Member]
Ownership interest by noncontrolling interest owner			2.00%
Chipeta [Member]
Ownership interest by noncontrolling interest owner			25.00%
WES [Member] | WES Operating [Member]
Ownership interest			98.00%
Occidental [Member] | WES [Member]
Ownership interest			53.40%
General partner's interest	2.00%		2.00%
Common units outstanding			242,136,976
Occidental [Member] | WES [Member] | Common Units [Member]
Common units outstanding	9,060,641
Occidental [Member] | WES Operating [Member]
Ownership interest			2.00%
WES Operating [Member]
Cash contribution from related party			$ 20,000,000
Revenues and other			774,313,000	671,883,000
WES Operating [Member] | Affiliates [Member]
Revenues and other			482,385,000	378,437,000
WES Operating [Member] | Affiliates [Member] | Product Sales [Member]
Revenues and other			$ 31,624,000	$ 50,443,000
WES Operating [Member] | RCF [Member] | Revolving Credit Facility [Member]
Facility, maximum borrowing capacity							$ 2,000,000,000
WES Operating [Member] | Term Loan Facility [Member] | Revolving Credit Facility [Member]
Facility, maximum borrowing capacity						$ 3,000,000,000

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Revenue From Contracts With Customers Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from customers	$ 714,491	$ 672,153
Revenue from other than customers, other	347	397
Total revenues and other	774,313	671,883
Service Revenues - Fee Based [Member]
Disaggregation of Revenue [Line Items]
Revenue from customers	641,921	579,974
Service Revenues - Product Based [Member]
Disaggregation of Revenue [Line Items]
Revenue from customers	15,921	19,379
Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from customers	56,649	72,800
Leases Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from other than customers	59,475	0
Commodity-Price Swap Agreement [Member]
Disaggregation of Revenue [Line Items]
Revenue from other than customers	$ 0	$ (667)

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Contract Assets Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Change in Contracts with Customer, Asset [Roll Forward]
Balance at December 31, 2019	$ 67,357
Additional estimated revenues recognized	5,365
Balance at March 31, 2020	72,722
Contract assets at March 31, 2020
Other current assets		$ 12,975	$ 7,129
Other assets		59,747
Total contract assets from contracts with customers	$ 72,722	$ 72,722	$ 67,357

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Contract Liabilities Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Change in Contracts with Customer, Liability [Roll Forward]
Balance at December 31, 2019	$ 222,274
Cash received or receivable, excluding revenues recognized during the period	11,203
Revenues recognized that were included in the contract liability balance at the beginning of the period	(8,893)
Balance at March 31, 2020	224,584
Contract liabilities at March 31, 2020
Accrued liabilities		$ 9,120	$ 19,659
Other liabilities		215,464
Total contract liabilities from contracts with customers	$ 224,584	$ 224,584	$ 222,274

Revenue from Contracts with C_6

Revenue from Contracts with Customers - Expected Revenues Table (Details) $ in Thousands	Mar. 31, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 572,077
Performance obligation expected to be satisfied, expected timing	9 months
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	$ 779,098
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	$ 1,035,119
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 978,409
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 948,700
Performance obligation expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected to be satisfied	$ 7,860,477
Performance obligation expected to be satisfied, expected timing

Revenue from Contracts with C_7

Revenue from Contracts with Customers - Additional Information (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Revenue from Contracts with Customer [Line Items]
Accounts receivable, net	[1]	$ 257,239	$ 260,512
Customers [Member]
Revenue from Contracts with Customer [Line Items]
Accounts receivable, net		$ 331,800	$ 362,600
[1]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $124.9 million and $113.3 million as of March 31, 2020 , and December 31, 2019 , respectively.

Acquisitions and Divestitures -

Acquisitions and Divestitures - Additional Information (Details) - USD ($) $ in Millions	Feb. 28, 2019	Jan. 18, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Property, Plant and Equipment [Line Items]
Limited partner units			443,971,409	443,971,409
WES Operating [Member] | Anadarko [Member] | Common Units [Member]
Property, Plant and Equipment [Line Items]
Limited partner units					6,400,000
Mi Vida [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	50.00%
Ranch Westex [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	50.00%
Saddlehorn [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	20.00%
Panola [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired	15.00%
Red Bluff Express [Member]
Property, Plant and Equipment [Line Items]
Ownership percentage acquired		30.00%
Acquisition, net investment		$ 92.5
Anadarko Midstream Assets [Member] | WES Operating [Member] | Common Units [Member]
Property, Plant and Equipment [Line Items]
Units issued	45,760,201
Anadarko Midstream Assets [Member] | WES Operating [Member] | Anadarko [Member] | Common Units [Member]
Property, Plant and Equipment [Line Items]
Limited partner units	6,375,284
Anadarko [Member] | Anadarko Midstream Assets [Member] | WES Operating [Member]
Property, Plant and Equipment [Line Items]
Cash payment for acquisition	$ 2,000

Partnership Distributions - Cas

Partnership Distributions - Cash Distributions Tables (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Distribution Made to Limited Partner [Line Items]
Total quarterly per-unit distribution	$ 0.31100	$ 0.62200	$ 0.62000	$ 0.61800	$ 0.61000
Total quarterly cash distribution	$ 140,893	$ 281,786	$ 280,880	$ 279,959	$ 276,324
WES Operating [Member]
Distribution Made to Limited Partner [Line Items]
Total quarterly cash distribution	$ 143,404	$ 290,314	$ 289,676	$ 288,083	$ 283,271

Partnership Distributions - Add

Partnership Distributions - Additional Information (Details) - shares	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Distribution Made to Limited Partner [Line Items]
Partnership agreement day requirement of distribution of available cash	55 days
Common units outstanding	443,971,409	443,971,409
WES Operating [Member] | Anadarko [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding			6,400,000
WES [Member] | Occidental [Member]
Distribution Made to Limited Partner [Line Items]
Distribution sharing percentage	2.00%
Common units outstanding	242,136,976
WES [Member] | Occidental [Member] | Common Units [Member]
Distribution Made to Limited Partner [Line Items]
Common units outstanding		9,060,641

Equity and Partners' Capital -

Equity and Partners' Capital - Additional Information (Details) - shares	Dec. 31, 2019	Nov. 30, 2014	Mar. 31, 2020	Feb. 28, 2019
Schedule of Investments [Line Items]
Common units outstanding	443,971,409		443,971,409
General partner units outstanding	9,060,641		9,060,641
WES [Member] | Public [Member]
Schedule of Investments [Line Items]
Common units outstanding			201,834,433
Limited partner's interest			44.60%
Occidental [Member] | WES [Member]
Schedule of Investments [Line Items]
Common units outstanding			242,136,976
Limited partner's interest			53.40%
General partner units outstanding			9,060,641
General partner's interest	2.00%		2.00%
Occidental [Member] | WES Operating [Member]
Schedule of Investments [Line Items]
Limited partner's interest			2.00%
WES [Member] | WES Operating [Member]
Schedule of Investments [Line Items]
Limited partner's interest			98.00%
WES Operating [Member] | Class C Units [Member]
Schedule of Investments [Line Items]
Class C units, common units issued upon conversion				1
WES Operating [Member] | Class C Units [Member] | Other Subsidiaries of Anadarko [Member]
Schedule of Investments [Line Items]
Units issued		10,913,853

Related-Party Transactions - Su

Related-Party Transactions - Summary of WES Related-Party Transactions Tables (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Related Party Transaction [Line Items]
Revenues and other		$ 774,313	$ 671,883
Equity income, net – related parties		61,347	57,992
Cost of product	[1]	103,270	114,063
Operation and maintenance	[1]	159,191	142,829
General and administrative	[1]	40,465	22,844
Operating expenses		1,050,523	410,357
Interest income		4,225	4,225
Interest expense		88,586	65,876
Distributions to unitholders	[2]	281,786	131,910
Above-market component of swap agreements with Anadarko	[2]	0	7,407
Affiliates [Member]
Related Party Transaction [Line Items]
Revenues and other		482,385	378,437
Cost of product		77,903	56,172
Operation and maintenance		32,841	39,141
General and administrative		21,855	18,894
Operating expenses		132,599	114,207
Interest expense		43	1,833
APCWH Note Payable borrowings		0	11,000
Repayment of APCWH Note Payable		0	439,595
Distributions to unitholders		150,609	102,654
Affiliates [Member] | WES Operating [Member]
Related Party Transaction [Line Items]
Distributions to unitholders		$ 5,807	$ 2,543
[1]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.9 million and $18.9 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .
[2]	See Note 6 .

Related-Party Transactions - _2

Related-Party Transactions - Summary of WES Operating Related-Party Transactions Tables (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Related Party Transaction [Line Items]
General and administrative	[1]	$ 40,465	$ 22,844
Distributions to WES Operating unitholders	[2]	281,786	131,910
Affiliates [Member]
Related Party Transaction [Line Items]
General and administrative		21,855	18,894
Distributions to WES Operating unitholders		150,609	102,654
WES Operating [Member]
Related Party Transaction [Line Items]
General and administrative	[3]	39,058	20,560
Distributions to WES Operating unitholders	[4]	290,314	263,358
WES Operating [Member] | Affiliates [Member]
Related Party Transaction [Line Items]
General and administrative		21,738	18,498
Distributions to WES Operating unitholders		$ 290,314	$ 164,902
[1]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.9 million and $18.9 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .
[2]	See Note 6 .
[3]	Cost of product includes product purchases from related parties (as defined in Note 1 ) of $77.9 million and $56.2 million for the three months ended March 31, 2020 and 2019 , respectively. Operation and maintenance includes charges from related parties of $32.8 million and $39.1 million for the three months ended March 31, 2020 and 2019 , respectively. General and administrative includes charges from related parties of $21.7 million and $18.5 million for the three months ended March 31, 2020 and 2019 , respectively. See Note 6 .
[4]	See Note 6 .

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended
		May 31, 2008	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Capital contribution for the above-market component of swap agreements with Anadarko	[1]			$ 7,407,000
Incentive Plans [Member]
Related Party Transaction [Line Items]
Allocated equity-based compensation expense			$ 4,100,000	$ 1,800,000
Natural Gas [Member]
Related Party Transaction [Line Items]
Related-party throughput percentage			42.00%	36.00%
Crude Oil and NGLs Member]
Related Party Transaction [Line Items]
Related-party throughput percentage			89.00%	81.00%
Produced water [Member]
Related Party Transaction [Line Items]
Related-party throughput percentage			89.00%	84.00%
WES Operating [Member]
Related Party Transaction [Line Items]
Capital contribution for the above-market component of swap agreements with Anadarko	[2]			$ 7,407,000
Cash contribution from related party			$ 20,000,000
Affiliates [Member]
Related Party Transaction [Line Items]
Operating lease, fixed-lease revenue			43,900,000
Operating lease, variable-lease revenue			15,600,000
Note receivable - Anadarko		$ 260,000,000
Fixed annual rate for note receivable bearing interest		6.50%
Interest receivable			2,800,000
Allowance for expected credit loss			2,100,000
Affiliates [Member] | Commodity-Price Swap Agreement [Member]
Related Party Transaction [Line Items]
Net gains (losses) on commodity-price swap agreements				$ (700,000)
Affiliates [Member] | Level-2 Inputs [Member] | Valuation, Market Approach [Member]
Related Party Transaction [Line Items]
Fair value of the note receivable			$ 153,600,000		$ 337,700,000
[1]	See Note 6 .
[2]	See Note 6 .

Equity Investments - Equity Inv

Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Balance	$ 1,285,717
Equity income, net	61,347	$ 57,992
Contributions	10,960	36,543
Distributions	(60,868)	(54,221)
Distributions in excess of cumulative earnings	(5,052)	$ (7,792)
Balance	1,292,104
Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance	(610)
Equity income, net	155
Contributions	0
Distributions	0
Distributions in excess of cumulative earnings	0
Balance	(455)
White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance	45,877
Equity income, net	2,373
Contributions	0
Distributions	(2,227)
Distributions in excess of cumulative earnings	(382)
Balance	45,641
Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance	32,964
Equity income, net	78
Contributions	0
Distributions	(564)
Distributions in excess of cumulative earnings	(789)
Balance	31,689
Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance	103,036
Equity income, net	7,046
Contributions	0
Distributions	(7,056)
Distributions in excess of cumulative earnings	(919)
Balance	102,107
Texas Express Gathering [Member]
Schedule of Equity Method Investments [Line Items]
Balance	18,199
Equity income, net	1,062
Contributions	0
Distributions	(1,068)
Distributions in excess of cumulative earnings	(1,147)
Balance	17,046
Texas Express Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Balance	203,556
Equity income, net	8,710
Contributions	0
Distributions	(10,120)
Distributions in excess of cumulative earnings	0
Balance	202,146
Front Range Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Balance	207,782
Equity income, net	9,798
Contributions	3,670
Distributions	(11,185)
Distributions in excess of cumulative earnings	(648)
Balance	209,417
Whitethorn LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance	161,665
Equity income, net	10,242
Contributions	278
Distributions	(8,558)
Distributions in excess of cumulative earnings	0
Balance	163,627
Cactus II [Member]
Schedule of Equity Method Investments [Line Items]
Balance	172,165
Equity income, net	8,008
Contributions	6,360
Distributions	(7,608)
Distributions in excess of cumulative earnings	0
Balance	178,925
Saddlehorn [Member]
Schedule of Equity Method Investments [Line Items]
Balance	112,855
Equity income, net	6,738
Contributions	0
Distributions	(7,254)
Distributions in excess of cumulative earnings	0
Balance	112,339
Panola [Member]
Schedule of Equity Method Investments [Line Items]
Balance	21,783
Equity income, net	438
Contributions	0
Distributions	(438)
Distributions in excess of cumulative earnings	(287)
Balance	21,496
Mi Vida [Member]
Schedule of Equity Method Investments [Line Items]
Balance	57,807
Equity income, net	2,308
Contributions	0
Distributions	(1,396)
Distributions in excess of cumulative earnings	0
Balance	58,719
Ranch Westex [Member]
Schedule of Equity Method Investments [Line Items]
Balance	46,678
Equity income, net	3,189
Contributions	0
Distributions	(2,192)
Distributions in excess of cumulative earnings	(705)
Balance	46,970
Red Bluff Express [Member]
Schedule of Equity Method Investments [Line Items]
Balance	101,960
Equity income, net	1,202
Contributions	652
Distributions	(1,202)
Distributions in excess of cumulative earnings	(175)
Balance	$ 102,437

Property, Plant, and Equipmen_2

Property, Plant, and Equipment - Historical Cost Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 12,545,357	$ 12,355,671
Less accumulated depreciation	3,558,626	3,290,740
Net property, plant, and equipment	8,986,731	9,064,931
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	9,495	9,495
Gathering Systems – Pipelines [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 5,163,286	5,092,004
Estimated useful life	30 years
Gathering Systems – Compressors [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 2,006,896	1,929,377
Estimated useful life	15 years
Processing Complexes And Treating Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 3,370,462	3,237,801
Estimated useful life	25 years
Transportation Pipeline And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 171,111	173,572
Transportation Pipeline And Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Transportation Pipeline And Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Produced-Water Disposal Systems [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 791,882	754,774
Estimated useful life	20 years
Assets Under Construction [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 337,000	486,584
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 695,225	$ 672,064
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 Equipmen_3

Property, Plant, and Equipment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Long-lived asset impairments	$ 155,785	$ 390	$ 6,300
Wyoming and Utah Assets [Member]
Property, Plant and Equipment [Line Items]
Long-lived asset impairments	145,100
Wyoming and Utah Assets [Member] | Fair Value, Nonrecurring [Member] | Level-3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value	91,000
Estimated salvage value	6,700
DJ Basin Complex [Member]
Property, Plant and Equipment [Line Items]
Long-lived asset impairments	$ 10,700

Goodwill - Additional Informati

Goodwill - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)
Goodwill [Line Items]
Number of reporting units	2
Goodwill impairment	$ 441,017,000	$ 0
Goodwill	4,783,000		$ 445,800,000
Gathering and Processing Reporting Unit [Member]
Goodwill [Line Items]
Goodwill	0
Transportation Reporting Unit [Member]
Goodwill [Line Items]
Goodwill	$ 4,800,000

Components of Working Capital -

Components of Working Capital - Accounts Receivable, Net Table (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Trade receivables, net		$ 254,314	$ 260,458
Other receivables, net		2,925	54
Total accounts receivable, net	[1]	257,239	260,512
WES Operating [Member]
Trade receivables, net		246,918	260,694
Other receivables, net		2,925	54
Total accounts receivable, net	[2]	$ 249,843	$ 260,748
[1]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $124.9 million and $113.3 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Accounts receivable, net includes amounts receivable from related parties (as defined in Note 1 ) of $117.5 million and $113.6 million as of March 31, 2020 , and December 31, 2019 , respectively.

Components of Working Capital_2

Components of Working Capital - Other Current Assets Table (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
NGLs inventory		$ 469	$ 906
Materials and supplies inventory		50,291	23,444
Imbalance receivables		6,683	4,690
Prepaid insurance		3,785	5,676
Contract assets		12,975	7,129
Other		6,824	93
Total other current assets	[1]	81,027	41,938
WES Operating [Member]
NGLs inventory		469	906
Materials and supplies inventory		50,291	23,444
Imbalance receivables		6,683	4,690
Prepaid insurance		2,082	3,652
Contract assets		12,975	7,129
Other		6,824	93
Total other current assets	[2]	$ 79,324	$ 39,914
[1]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019
[2]	Other current assets includes related-party amounts of $9.0 million and $5.0 million as of March 31, 2020 , and December 31, 2019 , respectively.

Components of Working Capital_3

Components of Working Capital - Accrued Liabilities Table (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Accrued interest expense		$ 82,818	$ 72,064
Short-term asset retirement obligations		29,633	22,472
Short-term remediation and reclamation obligations		3,528	3,528
Income taxes payable		0	697
Contract liabilities		9,120	19,659
Other		41,639	31,373
Total accrued liabilities	[1]	166,738	149,793
WES Operating [Member]
Accrued interest expense		82,818	72,064
Short-term asset retirement obligations		29,633	22,472
Short-term remediation and reclamation obligations		3,528	3,528
Income taxes payable		0	697
Contract liabilities		9,120	19,659
Other		35,076	31,219
Total accrued liabilities	[2]	$ 160,175	$ 149,639
[1]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.

Debt and Interest Expense - Deb

Debt and Interest Expense - Debt Outstanding Table (Details) - USD ($)		Mar. 31, 2020	Jan. 13, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Short-term debt, principal		$ 11,184,000		$ 7,873,000
Short-term debt, carrying value	[1]	11,184,000		7,873,000
Long-term debt, carrying value		8,088,761,000		7,951,565,000
Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Short-term debt, fair value		11,184,000		7,873,000
Long-Term Debt Obligations [Member]
Debt Instrument [Line Items]
Total long-term debt, principal		8,173,990,000		8,000,000,000
Long-term debt, carrying value		8,088,761,000		7,951,565,000
Long-Term Debt Obligations [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		4,026,415,000		7,849,818,000
WES Operating [Member]
Debt Instrument [Line Items]
Short-term debt, carrying value	[2]	11,184,000		7,873,000
Long-term debt, carrying value		8,088,761,000		7,951,565,000
WES Operating [Member] | Finance Lease Liability, Short Term [Member]
Debt Instrument [Line Items]
Principal		11,184,000		7,873,000
Short-term debt, carrying value		11,184,000		7,873,000
WES Operating [Member] | Finance Lease Liability, Short Term [Member] | Affiliates [Member]
Debt Instrument [Line Items]
Short-term debt, carrying value		2,600,000		7,900,000
WES Operating [Member] | Finance Lease Liability, Short Term [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Short-term debt, fair value		11,184,000		7,873,000
WES Operating [Member] | RCF [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal		125,000,000		380,000,000
Long-term debt, carrying value		125,000,000		380,000,000
WES Operating [Member] | RCF [Member] | Revolving Credit Facility [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		125,000,000		380,000,000
WES Operating [Member] | Term Loan Facility [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal		0		3,000,000,000
Long-term debt, carrying value		0		3,000,000,000
WES Operating [Member] | Term Loan Facility [Member] | Revolving Credit Facility [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		0		3,000,000,000
WES Operating [Member] | Finance Lease Liability, Long Term [Member]
Debt Instrument [Line Items]
Principal		28,990,000		0
Long-term debt, carrying value		28,990,000		0
WES Operating [Member] | Finance Lease Liability, Long Term [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 28,990,000		0
WES Operating [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		5.375%
Principal		$ 438,631,000		500,000,000
Long-term debt, carrying value		437,300,000		498,168,000
WES Operating [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 352,437,000		515,042,000
WES Operating [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		4.00%
Principal		$ 631,369,000		670,000,000
Long-term debt, carrying value		630,790,000		669,322,000
WES Operating [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		408,183,000		689,784,000
WES Operating [Member] | Senior Notes [Member] | Floating-Rate Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Principal		300,000,000		0
Long-term debt, carrying value		298,118,000		0
WES Operating [Member] | Senior Notes [Member] | Floating-Rate Senior Notes due 2023 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 158,400,000		0
WES Operating [Member] | Senior Notes [Member] | 3.100% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		3.10%	3.10%
Principal		$ 1,000,000,000		0
Long-term debt, carrying value		991,713,000		0
WES Operating [Member] | Senior Notes [Member] | 3.100% Senior Notes due 2025 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 509,618,000		0
WES Operating [Member] | Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		3.95%
Principal		$ 500,000,000		500,000,000
Long-term debt, carrying value		494,086,000		493,830,000
WES Operating [Member] | Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 254,103,000		504,968,000
WES Operating [Member] | Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		4.65%
Principal		$ 500,000,000		500,000,000
Long-term debt, carrying value		496,323,000		496,197,000
WES Operating [Member] | Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 258,950,000		513,393,000
WES Operating [Member] | Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		4.50%
Principal		$ 400,000,000		400,000,000
Long-term debt, carrying value		395,236,000		395,113,000
WES Operating [Member] | Senior Notes [Member] | 4.500% Senior Notes due 2028 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 191,693,000		390,920,000
WES Operating [Member] | Senior Notes [Member] | 4.750% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		4.75%
Principal		$ 400,000,000		400,000,000
Long-term debt, carrying value		396,280,000		396,190,000
WES Operating [Member] | Senior Notes [Member] | 4.750% Senior Notes due 2028 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 189,498,000		400,962,000
WES Operating [Member] | Senior Notes [Member] | 4.050% Senior Notes due 2030 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		4.05%	4.05%
Principal		$ 1,200,000,000		0
Long-term debt, carrying value		1,188,718,000		0
WES Operating [Member] | Senior Notes [Member] | 4.050% Senior Notes due 2030 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 500,911,000		0
WES Operating [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		5.45%
Principal		$ 600,000,000		600,000,000
Long-term debt, carrying value		593,501,000		593,470,000
WES Operating [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 224,905,000		533,710,000
WES Operating [Member] | Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		5.30%
Principal		$ 700,000,000		700,000,000
Long-term debt, carrying value		686,893,000		686,843,000
WES Operating [Member] | Senior Notes [Member] | 5.300% Senior Notes due 2048 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 277,851,000		610,841,000
WES Operating [Member] | Senior Notes [Member] | 5.500% Senior Notes due 2048 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		5.50%
Principal		$ 350,000,000		350,000,000
Long-term debt, carrying value		342,459,000		342,432,000
WES Operating [Member] | Senior Notes [Member] | 5.500% Senior Notes due 2048 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 132,332,000		310,198,000
WES Operating [Member] | Senior Notes [Member] | 5.250% Senior Notes due 2050 [Member]
Debt Instrument [Line Items]
Senior note, interest rate		5.25%	5.25%
Principal		$ 1,000,000,000		0
Long-term debt, carrying value		983,354,000		0
WES Operating [Member] | Senior Notes [Member] | 5.250% Senior Notes due 2050 [Member] | Valuation, Market Approach [Member] | Level-2 Inputs [Member]
Debt Instrument [Line Items]
Long-term debt, fair value		$ 413,544,000		$ 0
[1]	Short-term debt includes related-party amounts for finance leases of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Short-term debt includes related-party amounts for finance leases of $2.6 million and $7.9 million as of March 31, 2020 , and December 31, 2019 , respectively.

Debt and Interest Expense - D_2

Debt and Interest Expense - Debt Activity Table (Details) - USD ($)	Jan. 31, 2020	Mar. 31, 2020
Changes in Debt Outstanding [Roll Forward]
Beginning balance		$ 7,959,438,000
Other		(36,793,000)
Ending balance		8,099,945,000
WES Operating [Member] | RCF [Member] | Revolving Credit Facility [Member]
Changes in Debt Outstanding [Roll Forward]
Facility borrowings		125,000,000
Repayments of facility borrowings		(380,000,000)
WES Operating [Member] | Floating-Rate Senior Notes due 2023 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes		300,000,000
WES Operating [Member] | 3.100% Senior Notes due 2025 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes		1,000,000,000
WES Operating [Member] | 4.050% Senior Notes due 2030 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes		1,200,000,000
WES Operating [Member] | 5.250% Senior Notes due 2050 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Issuance of senior notes		1,000,000,000
WES Operating [Member] | Finance Lease Liability [Member]
Changes in Debt Outstanding [Roll Forward]
Finance lease liabilities		32,300,000
WES Operating [Member] | Term Loan Facility [Member] | Revolving Credit Facility [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments of facility borrowings	$ (3,000,000,000)	(3,000,000,000)
WES Operating [Member] | 5.375% Senior Notes due 2021 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments of senior notes		(61,369,000)
WES Operating [Member] | 4.000% Senior Notes due 2022 [Member] | Senior Notes [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments of senior notes		$ (38,631,000)

Debt and Interest Expense - Int

Debt and Interest Expense - Interest Expense Table (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
Interest expense	$ (88,586)	$ (65,876)
Third Parties [Member]
Debt Instrument [Line Items]
Long-term and short-term debt	(89,769)	(67,096)
Finance lease liabilities	(405)	0
Amortization of debt issuance costs and commitment fees	(3,127)	(3,152)
Capitalized interest	4,758	6,205
Interest expense	(88,543)	(64,043)
Affiliates [Member]
Debt Instrument [Line Items]
Finance lease liabilities	(43)	0
Interest expense	(43)	(1,833)
Affiliates [Member] | APCWH Note Payable [Member]
Debt Instrument [Line Items]
APCWH Note Payable	$ 0	$ (1,833)

Debt and Interest Expense - Add

Debt and Interest Expense - Additional Information (Details) - USD ($)		Jan. 31, 2020	Jan. 13, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Jul. 01, 2019	Feb. 28, 2019	Dec. 31, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					$ 7,345,000		$ 0
Accrued liability on interest-rate swaps	[1]				166,738,000	$ 149,793,000
Gain (loss) on interest-rate swaps					0		(35,638,000)
Affiliates [Member]
Debt Instrument [Line Items]
Accrued liability on interest-rate swaps					2,500,000	3,100,000
WES [Member] | Revolving Credit Facility [Member] | WGP RCF [Member]
Debt Instrument [Line Items]
Facility, repayment of borrowings							28,000,000
WES Operating [Member]
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					7,345,000		0
Accrued liability on interest-rate swaps	[2]				160,175,000	149,639,000
Gain (loss) on interest-rate swaps					0		(35,638,000)
WES Operating [Member] | Interest-Rate Swap [Member]
Debt Instrument [Line Items]
Cash paid to settle interest-rate swaps						107,700,000
Gain (loss) on interest-rate swaps							35,600,000
WES Operating [Member] | Not Designated as Hedging Instrument [Member] | Interest-Rate Swap [Member]
Debt Instrument [Line Items]
Interest-rate swap, notional amount						1,125,000,000	$ 375,000,000			$ 750,000,000
Accrued liability on interest-rate swaps						25,600,000
WES Operating [Member] | Affiliates [Member]
Debt Instrument [Line Items]
Future lease payments					2,600,000
Accrued liability on interest-rate swaps					2,500,000	$ 3,100,000
WES Operating [Member] | Third Parties [Member]
Debt Instrument [Line Items]
Future lease payments					43,500,000
WES Operating [Member] | Revolving Credit Facility [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Facility, repayment of borrowings		$ 3,000,000,000			3,000,000,000
Gain (loss) on early extinguishment of debt					2,300,000
Facility, maximum borrowing capacity								$ 3,000,000,000
Facility, interest rate at period end							3.87%
WES Operating [Member] | Revolving Credit Facility [Member] | RCF [Member]
Debt Instrument [Line Items]
Facility, repayment of borrowings					380,000,000
Facility, expandable maximum borrowing capacity									$ 2,500,000,000
Facility, maximum borrowing capacity									$ 2,000,000,000
Facility, outstanding borrowings					125,000,000
Facility, outstanding letters of credit					6,500,000
Facility, available borrowing capacity					$ 1,900,000,000
Facility, interest rate at period end					2.13%		3.79%
Facility, fee rate					0.20%		0.20%
WES Operating [Member] | Revolving Credit Facility [Member] | RCF [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Facility, fee rate				0.25%
Facility, interest rate increase				0.20%
Facility, fee rate increase				0.05%
WES Operating [Member] | Revolving Credit Facility [Member] | RCF [Member] | Non-Extending Lender [Member]
Debt Instrument [Line Items]
Facility, borrowing capacity for non-extending lender					$ 100,000,000
WES Operating [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					$ 9,600,000
WES Operating [Member] | Senior Notes [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Borrowing costs increase				$ 17,500,000
WES Operating [Member] | Senior Notes [Member] | 3.100% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Senior note, interest rate			3.10%		3.10%
Senior note, offering percent			99.962%
Senior note, effective interest rate					3.287%
WES Operating [Member] | Senior Notes [Member] | 4.050% Senior Notes due 2030 [Member]
Debt Instrument [Line Items]
Senior note, interest rate			4.05%		4.05%
Senior note, offering percent			99.90%
Senior note, effective interest rate					4.168%
WES Operating [Member] | Senior Notes [Member] | 5.250% Senior Notes due 2050 [Member]
Debt Instrument [Line Items]
Senior note, interest rate			5.25%		5.25%
Senior note, offering percent			99.442%
Senior note, effective interest rate					5.362%
WES Operating [Member] | Senior Notes [Member] | Floating-Rate Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Senior note, effective interest rate					2.69%
WES Operating [Member] | Senior Notes [Member] | Floating-Rate Senior Notes due 2023 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Alternate Base Rate [Member]
Debt Instrument [Line Items]
Facility, applicable margin added			0.85%
WES Operating [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Senior note, interest rate					5.375%
Repayments of senior notes					$ 61,369,000
WES Operating [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior note, interest rate					4.00%
Repayments of senior notes					$ 38,631,000
Maximum [Member] | WES Operating [Member] | APCWH Note Payable [Member]
Debt Instrument [Line Items]
APCWH Note Payable, maximum borrowing											$ 500,000,000
[1]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.
[2]	Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020 , and December 31, 2019 , respectively.