Consolidated Statements of Cash Flows - WES Operating - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income (loss)		$ 516,852		$ 807,700	$ 630,654
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		491,086		483,255	389,164
Long-lived asset and other impairments		203,889		6,279	230,584
Goodwill impairment		441,017		0	0
Non-cash equity-based compensation expense		22,462		15,494	6,431
Deferred income taxes		3,296		7,609	139,048
Accretion and amortization of long-term obligations, net		8,654		8,441	5,943
Equity income, net – related parties		(226,750)		(237,518)	(195,469)
Distributions from equity-investment earnings – related parties		246,637		234,572	187,392
(Gain) loss on divestiture and other, net		(8,634)		1,406	(1,312)
(Gain) loss on early extinguishment of debt		(11,234)		0	0
(Gain) loss on interest-rate swaps		0		125,334	7,972
Cash paid to settle interest-rate swaps		(25,621)		(107,685)	0
Other		193		236	752
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		(193,688)		(45,033)	(60,502)
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		144,437		(30,866)	45,605
Change in other items, net		24,822		54,876	(38,087)
Net cash provided by operating activities		1,637,418		1,324,100	1,348,175
Cash flows from investing activities
Capital expenditures		(423,091)		(1,188,829)	(1,948,595)
Contributions to equity investments – related parties		(19,388)		(128,393)	(133,629)
Distributions from equity investments in excess of cumulative earnings – related parties		32,160		30,256	29,585
Proceeds from the sale of assets to third parties		20,333		342	3,938
Additions to materials and supplies inventory and other		(57,757)		0	0
Net cash used in investing activities		(448,254)		(3,387,853)	(2,210,813)
Cash flows from financing activities
Borrowings, net of debt issuance costs	[1]	3,681,173		4,169,695	2,671,337
Repayments of debt	[2]	(3,803,888)		(1,467,595)	(1,040,000)
Increase (decrease) in outstanding checks		20,699		1,571	(3,206)
Distributions to WES Operating unitholders	[3]	(695,834)		(969,073)	(502,457)
Net contributions from (distributions to) related parties		24,466		458,819	97,755
Above-market component of swap agreements with Anadarko	[3]	0		7,407	51,618
Finance lease payments	[4]	(14,207)		(508)	0
Net cash provided by (used in) financing activities		(844,204)		2,071,573	875,192
Net increase (decrease) in cash and cash equivalents		344,960		7,820	12,554
Cash and cash equivalents at beginning of period		99,962		92,142	79,588
Cash and cash equivalents at end of period		444,922		99,962	92,142
Supplemental disclosures
Non-cash Consideration Transferred to Related Party	[3]	(261,878)		0	0
Net distributions to (contributions from) Anadarko of other assets		(24,466)	[5]	90	(58,835)
Interest paid, net of capitalized interest		349,913		293,795	140,720
Taxes paid (reimbursements received)		(384)		96	2,408
Accrued capital expenditures		25,126		140,954	274,632
Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(8,644)		(9,663)	(13,529)
Related Parties [Member]
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
(Gain) loss on divestiture and other, net		2,870		0	0
Cash flows from investing activities
Acquisitions		0		(2,007,926)	(254)
Cash flows from financing activities
Borrowings, net of debt issuance costs				11,000	321,800
Repayments of debt				(439,600)
Distributions to WES Operating unitholders		(367,861)		(566,868)	(400,194)
Finance lease payments		(6,382)		(508)	0
Supplemental disclosures
Net distributions to (contributions from) Anadarko of other assets		0		90	(58,835)
Accrued capital expenditures		2,000
Third Parties [Member]
Cash flows from investing activities
Acquisitions		(511)		(93,303)	(161,858)
WES Operating [Member]
Cash flows from operating activities
Net income (loss)		520,387		814,685	636,526
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		491,086		483,255	389,164
Long-lived asset and other impairments		203,889		6,279	230,584
Goodwill impairment		441,017		0	0
Non-cash equity-based compensation expense		14,604		14,235	6,153
Deferred income taxes		3,296		7,609	139,048
Accretion and amortization of long-term obligations, net		8,654		8,421	5,142
Equity income, net – related parties		(226,750)		(237,518)	(195,469)
Distributions from equity-investment earnings – related parties		246,637		234,572	187,392
(Gain) loss on divestiture and other, net		(8,634)		1,406	(1,312)
(Gain) loss on early extinguishment of debt		(11,234)		0	0
(Gain) loss on interest-rate swaps		0		125,334	7,972
Cash paid to settle interest-rate swaps		(25,621)		(107,685)	0
Other		193		236	752
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		(147,041)		(44,939)	(60,460)
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		105,352		(29,745)	44,424
Change in other items, net		24,816		56,044	(37,802)
Net cash provided by operating activities		1,640,651		1,332,189	1,352,114
Cash flows from investing activities
Capital expenditures		(423,091)		(1,188,829)	(1,948,595)
Contributions to equity investments – related parties		(19,388)		(128,393)	(133,629)
Distributions from equity investments in excess of cumulative earnings – related parties		32,160		30,256	29,585
Proceeds from the sale of assets to third parties		20,333		342	3,938
Additions to materials and supplies inventory and other		(57,757)		0	0
Net cash used in investing activities		(448,254)		(3,387,853)	(2,210,813)
Cash flows from financing activities
Borrowings, net of debt issuance costs	[6]	3,681,173		4,169,695	2,671,344
Repayments of debt	[7]	(3,803,888)		(1,439,595)	(1,040,000)
Increase (decrease) in outstanding checks		20,664		1,571	(3,206)
Distributions to WES Operating unitholders	[8]	(771,546)		(1,124,388)	(893,649)
Net contributions from (distributions to) related parties		24,466		458,819	97,755
Above-market component of swap agreements with Anadarko	[8]	0		7,407	51,618
Finance lease payments	[9]	(14,207)		(508)	0
Net cash provided by (used in) financing activities		(871,982)		2,063,338	870,333
Net increase (decrease) in cash and cash equivalents		320,415		7,674	11,634
Cash and cash equivalents at beginning of period		98,122		90,448	78,814
Cash and cash equivalents at end of period		418,537		98,122	90,448
Supplemental disclosures
Non-cash Consideration Transferred to Related Party	[8]	(261,878)		0	0
Net distributions to (contributions from) Anadarko of other assets		(24,466)	[10]	90	(58,835)
Interest paid, net of capitalized interest		349,913		293,561	139,482
Taxes paid (reimbursements received)		(384)		96	2,408
Accrued capital expenditures		25,126		140,954	274,632
WES Operating [Member] | Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(8,644)		(9,663)	(13,529)
WES Operating [Member] | Related Parties [Member]
Cash flows from investing activities
Acquisitions		0		(2,007,926)	(254)
Cash flows from financing activities
Borrowings, net of debt issuance costs				11,000	321,800
Repayments of debt				(439,600)
Distributions to WES Operating unitholders		(771,546)		(1,025,931)	(514,906)
Finance lease payments		(6,400)
Supplemental disclosures
Net distributions to (contributions from) Anadarko of other assets		0		90	(58,835)
WES Operating [Member] | Third Parties [Member]
Cash flows from investing activities
Acquisitions		$ (511)		$ (93,303)	$ (161,858)

[1] For the years ended December 31, 2019 and 2018, includes $11.0 million and $321.8 million of borrowings, respectively, under the APCWH Note Payable.

[2] For the year ended December 31, 2019, includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6.

[3] See Note 6.

[4] For the year ended December 31, 2020, includes related-party payments of $6.4 million.

[5] See December 2019 Agreements—Services, Secondment, and Employee Transfer Agreement within Note 1.

[6] For the years ended December 31, 2019 and 2018, includes $11.0 million and $321.8 million of borrowings, respectively, under the APCWH Note Payable.

[7] For the year ended December 31, 2019, includes a $439.6 million repayment to settle the APCWH Note Payable. See Note 6.

[8] See Note 6.

[9] For the year ended December 31, 2020, includes related-party payments of $6.4 million.

[10] See December 2019 Agreements—Services, Secondment, and Employee Transfer Agreement within Note 1.