Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended									9 Months Ended			12 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018		Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Sep. 30, 2019	Sep. 30, 2018		Dec. 31, 2018
Revenues and Other
Revenues and other		$ 666,027			$ 587,900	[1]					$ 2,022,964	$ 1,607,032	[1]
Equity income, net – affiliates		53,893			54,215	[1]					175,483	133,874	[1]
Operating expenses
Cost of product	[2]	97,800			101,035	[1]					334,740	291,009	[1]
Operation and maintenance	[2]	176,572			129,042	[1]					467,832	338,626	[1]
General and administrative	[2]	30,769			16,022	[1]					83,640	47,448	[1]
Property and other taxes		15,281			13,146	[1]					45,848	41,496	[1]
Depreciation and amortization		127,914			97,479	[1]					362,977	270,757	[1]
Impairments		3,107			27,902	[1]					4,294	155,286	[1]	$ 230,600
Total operating expenses		451,443			384,626	[1]					1,299,331	1,144,622	[1]
Gain (loss) on divestiture and other, net		248			65	[1]					(1,403)	351	[1]
Operating income (loss)		268,725			257,554	[1]					897,713	596,635	[1]
Interest income – affiliates		4,225			4,225	[1]					12,675	12,675	[1]
Interest expense	[3]	(78,524)			(48,869)	[1]					(223,872)	(129,129)	[1]
Other income (expense), net		(67,894)			655	[1]					(161,577)	2,749	[1]
Income (loss) before income taxes		126,532			213,565	[1]					524,939	482,930	[1]
Income tax expense (benefit)		1,309			15,005	[1]					12,679	36,193	[1]
Net income (loss)		125,223	$ 175,058	$ 211,979	198,560	[1]	$ 67,167		$ 181,010		512,260	446,737	[1]
Net income (loss) attributable to noncontrolling interests		4,006			47,203	[1]					102,789	63,669	[1]
Net income (loss) attributable to Western Midstream Partners, LP		121,217			151,357	[1]					409,471	383,068	[1]
Limited partners' interest in net income (loss):
Net income (loss) attributable to Western Midstream Partners, LP		121,217			151,357	[1]					409,471	383,068	[1]
Pre-acquisition net (income) loss allocated to Anadarko		0			(43,883)	[1]					(29,279)	(107,009)	[1]
Limited partners' interest in net income (loss)		121,217			107,474	[1]					380,192	276,059	[1]
Affiliates [Member]
Revenues and Other
Revenues and other		398,753			350,291	[1]					1,162,374	925,011	[1]
Operating expenses
Cost of product		61,066			39,702						185,463	112,522
Operation and maintenance		39,459			29,794						110,918	79,621
General and administrative		27,724			12,645						73,510	37,595
Total operating expenses		128,249			82,141						369,891	229,738
Interest expense		(59)			(2,035)						(1,912)	(4,021)
Affiliates [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		360,011			277,923	[1]					1,030,137	734,473	[1]
Affiliates [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		84			881	[1]					2,070	2,050	[1]
Affiliates [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		38,658			71,487	[1]					130,167	188,488	[1]
Third Parties [Member]
Revenues and Other
Revenues and other		267,274			237,609	[1]					860,590	682,021	[1]
Operating expenses
Interest expense		(78,465)			(46,834)						(221,960)	(125,108)
Third Parties [Member] | Service Revenues - Fee Based [Member]
Revenues and Other
Revenues and other		227,954			208,406	[1]					731,346	577,490	[1]
Third Parties [Member] | Service Revenues - Product Based [Member]
Revenues and Other
Revenues and other		9,392			22,455	[1]					43,460	67,371	[1]
Third Parties [Member] | Product Sales [Member]
Revenues and Other
Revenues and other		29,590			5,512	[1]					84,683	35,451	[1]
Third Parties [Member] | Other [Member]
Revenues and Other
Revenues and other		$ 338			$ 1,236	[1]					$ 1,101	$ 1,709	[1]
Limited Partner [Member]
Limited partners' interest in net income (loss):
Net income (loss) per common unit - basic and diluted		$ 0.27			$ 0.49	[1]					$ 0.94	$ 1.26	[1]
Weighted-average common units outstanding - basic and diluted		453,021			218,938	[1]					402,421	218,935	[1]

[1] Financial information has been recast to include the financial position and results attributable to AMA. See Note 1 and Note 3.

[2] Cost of product includes product purchases from affiliates (as defined in Note 1) of $61.1 million and $185.5 million for the three and nine months ended September 30, 2019, respectively, and $39.7 million and $112.5 million for the three and nine months ended September 30, 2018, respectively. Operation and maintenance includes charges from affiliates of $39.5 million and $110.9 million for the three and nine months ended September 30, 2019, respectively, and $29.8 million and $79.6 million for the three and nine months ended September 30, 2018, respectively. General and administrative includes charges from affiliates of $27.7 million and $73.5 million for the three and nine months ended September 30, 2019, respectively, and $12.6 million and $37.6 million for the three and nine months ended September 30, 2018, respectively. See Note 6.

[3] Includes affiliate amounts of $0.06 million and $1.9 million for the three and nine months ended September 30, 2019, respectively, and $2.0 million and $4.0 million for the three and nine months ended September 30, 2018, respectively. See Note 1 and Note 10.