Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)					12 Months Ended
		Jan. 31, 2020	Dec. 31, 2019	Feb. 28, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 01, 2019	Dec. 19, 2018
Common units outstanding			443,971,409		443,971,409	218,937,797
Acquisitions					$ 92,546,000	$ 162,615,000
General partner units outstanding			9,060,641		9,060,641	0
Conversion ratio per unit				1.525
Revenues and other					$ 2,746,174,000	$ 2,299,658,000	$ 2,429,614,000
Impairments					6,279,000	230,584,000	180,051,000
Imbalance receivables			$ 4,690,000		4,690,000	9,035,000
Imbalance payables			$ 2,700,000		2,700,000	9,600,000
Gain (loss) on divestiture and other, net	[1],[2]				(1,406,000)	1,312,000	132,388,000
Proceeds from property insurance claims					$ 0	0	22,977,000
Western Gas Partners 2017 Long-Term Incentive Plan [Member]
Units available under LTIP			3,419,020		3,419,020
Western Gas Equity Partners 2012 Long-Term Incentive Plan [Member]
Units available under LTIP			2,911,985		2,911,985
Kitty Draw and Third Creek Gathering Systems [Member]
Impairments						134,000,000.0
Delaware Basin Midstream Complex [Member]
Gain (loss) on divestiture and other, net							(5,700,000)
Proceeds from insurance claims, total							52,900,000
Proceeds from business interruption insurance claims							29,900,000
Proceeds from property insurance claims							23,000,000.0
Affiliates [Member]
Revenues and other					$ 1,607,396,000	1,353,711,000	1,539,105,000
Affiliates [Member] | Product Sales [Member]
Revenues and other					158,459,000	280,306,000	753,724,000
Affiliates [Member] | Product Sales [Member] | Kitty Draw and Third Creek Gathering Systems [Member]
Revenues and other					$ 6,100,000	$ (10,900,000)
Anadarko Midstream Assets [Member]
Conversion ratio per unit				1.4056
Subsequent Event [Member]
Cash contribution from affiliate		$ 20,000,000.0
WES Operating [Member]
Ownership interest by noncontrolling interest owner			2.00%		2.00%
Chipeta [Member]
Ownership interest by noncontrolling interest owner			25.00%		25.00%
WES [Member] | Common Units [Member]
Common units outstanding				452,990,862		218,937,797
Conversion of units				178,692,081
WES [Member] | Common Units [Member] | Anadarko Midstream Assets [Member]
Conversion of units				55,360,984
WES [Member] | WES Operating [Member]
Ownership interest					98.00%
General partner units outstanding				2,583,068
WES [Member] | WES Operating [Member] | Common Units [Member]
Common units outstanding				50,132,046
Occidental [Member] | WES [Member]
Ownership interest					53.40%
General partner's interest			2.00%		2.00%
Common units outstanding			242,136,976		242,136,976
General partner units outstanding			9,060,641		9,060,641
Occidental [Member] | WES [Member] | Common Units [Member]
Common units outstanding			9,060,641		9,060,641
Occidental [Member] | WES Operating [Member]
Ownership interest					2.00%
WES Operating [Member]
Units issued					308,723	1,128,782
General partner units outstanding			0		0	2,583,068
Conversion of units					0
Revenues and other					$ 2,746,174,000	$ 2,299,658,000	2,429,614,000
Impairments					6,279,000	230,584,000	180,051,000
Imbalance receivables			$ 4,690,000		4,690,000	9,035,000
Gain (loss) on divestiture and other, net	[3],[4]				(1,406,000)	1,312,000	132,388,000
Proceeds from property insurance claims					0	0	22,977,000
WES Operating [Member] | Affiliates [Member]
Revenues and other					1,607,396,000	1,353,711,000	1,539,105,000
WES Operating [Member] | Affiliates [Member] | Product Sales [Member]
Revenues and other					$ 158,459,000	$ 280,306,000	$ 753,724,000
WES Operating [Member] | Anadarko Midstream Assets [Member]
Units issued					45,760,201
WES Operating [Member] | Anadarko Midstream Assets [Member] | Anadarko [Member]
Cash payment for acquisition				$ 1,814,000,000
Acquisitions				193,900,000
WES Operating [Member] | RCF [Member] | Revolving Credit Facility [Member]
Facility, maximum borrowing capacity				$ 2,000,000,000.0
WES Operating [Member] | Term Loan Facility [Member] | Revolving Credit Facility [Member]
Facility, maximum borrowing capacity								$ 3,000,000,000.0	$ 2,000,000,000.0
WES Operating [Member] | Common Units [Member]
Common units outstanding				152,609,285
Conversion of units				105,624,704	14,681,388
WES Operating [Member] | Common Units [Member] | Anadarko Midstream Assets [Member]
Units issued				45,760,201	45,760,201
WES Operating [Member] | Class C Units [Member]
Common units outstanding				14,681,388
Units issued					308,723	1,128,782
Class C units, common units issued upon conversion				1
Conversion of units					(14,681,388)
Anadarko [Member] | WES Operating [Member] | Common Units [Member]
Common units outstanding			6,400,000		6,400,000
Anadarko [Member] | WES Operating [Member] | Common Units [Member] | Anadarko Midstream Assets [Member]
Common units outstanding				6,375,284

[1] Includes losses related to an incident at the DBM complex for the year ended December 31, 2017. See Note 1.

[2] Includes losses related to an incident at the DBM complex for the year ended December 31, 2017. See Note 1.

[3] Includes losses related to an incident at the DBM complex for the year ended December 31, 2017. See Note 1.

[4] Includes losses related to an incident at the DBM complex for the year ended December 31, 2017. See Note 1.