Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Cash flows from operating activities
Net income (loss)		$ 448,512		$ 573,202		$ 596,980
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		337,536		290,874		272,933
Impairments		228,338		178,374		15,535
Non-cash equity-based compensation expense		6,431		5,169		4,986
Deferred income taxes		2,466		2,458		2,555
Accretion and amortization of long-term obligations, net		5,943		4,932		(3,262)
Equity income, net – affiliates	[1]	(153,024)		(85,194)		(78,717)
Distributions from equity investment earnings – affiliates		144,299		87,380		82,185
(Gain) loss on divestiture and other, net	[2]	(1,312)		(132,388)		14,641
(Gain) loss on interest-rate swaps		7,972		0		0
Lower of cost or market inventory adjustments		752		145		168
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net		(56,707)		(16,195)		(48,998)
Increase (decrease) in accounts and imbalance payables and accrued liabilities, net		31,903		(6,919)		58,365
Change in other items, net		13,586		(4,426)		(4,295)
Net cash provided by operating activities		1,016,695		897,412		913,076
Cash flows from investing activities
Capital expenditures		(1,193,896)		(675,025)		(479,993)
Investments in equity affiliates		(133,335)	[3]	(384)		(27)
Distributions from equity investments in excess of cumulative earnings – affiliates		25,607	[4]	23,085	[4]	21,238
Proceeds from property insurance claims		0		22,977		17,465
Net cash used in investing activities		(1,459,798)		(763,604)		(1,105,534)
Cash flows from financing activities
Borrowings, net of debt issuance costs		2,349,557		369,989		1,323,198
Repayments of debt		(1,040,000)		0		(900,000)
Increase (decrease) in outstanding checks		(3,206)		5,593		2,079
Distributions to WGP unitholders	[5]	(502,457)		(441,967)		(374,082)
Net contributions from (distributions to) Anadarko		0		1,263		(23,491)
Above-market component of swap agreements with Anadarko	[5]	51,618		58,551		45,820
Net cash provided by (used in) financing activities		455,657		(413,292)		451,836
Net increase (decrease) in cash and cash equivalents		12,554		(279,484)		259,378
Cash and cash equivalents at beginning of period		79,588		359,072		99,694
Cash and cash equivalents at end of period		92,142		79,588		359,072
Supplemental disclosures
Accretion expense and revisions to the Deferred purchase price obligation – Anadarko	[6]	0		(4,094)		(147,234)
Net distributions to (contributions from) Anadarko of other assets	[7]	0		(3,189)		581
Interest paid, net of capitalized interest		149,678		138,871		107,657
Taxes paid (reimbursements received)		2,408		1,194		838
Accrued capital expenditures		196,095		204,309		79,253
Fair value of properties and equipment from non-cash third party transactions	[6]	0		551,453		0
Chipeta [Member]
Cash flows from financing activities
Distributions to Chipeta noncontrolling interest owner		(13,529)		(13,569)		(13,784)
Western Gas Partners, LP [Member]
Cash flows from financing activities
Proceeds from the issuance of WES common units, net of offering expenses		0		(183)		0
Distributions to noncontrolling interest owners of WES		(386,326)		(355,623)		(294,841)
Affiliates [Member]
Cash flows from investing activities
Contributions in aid of construction costs from affiliates		0		1,387		6,135
Acquisitions		(254)		(3,910)		(716,465)
Proceeds from the sale of assets		0		0		623
Cash flows from financing activities
Settlement of the Deferred purchase price obligation - Anadarko	[6]	0		(37,346)		0
Distributions to WGP unitholders	[8]	(400,194)		(360,523)		(315,505)
Affiliates [Member] | Western Gas Partners, LP [Member]
Cash flows from financing activities
Distributions to WGP unitholders	[9]	(7,583)		(7,100)		(5,614)
Third Parties [Member]
Cash flows from investing activities
Acquisitions		(161,858)		(155,298)		0
Proceeds from the sale of assets		3,938		23,564		45,490
Series A Preferred Units [Member] | Western Gas Partners, LP [Member]
Cash flows from financing activities
Proceeds from the issuance of WES Series A Preferred units, net of offering expenses		$ 0		$ 0		$ 686,937

[1] Represents amounts earned or incurred on and subsequent to the date of the acquisition of WES assets, as well as amounts earned or incurred by Anadarko on a historical basis related to WES assets prior to the acquisition of such assets by WES.

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

[3] Includes capitalized interest of $1.4 million related to the construction of the Cactus II pipeline.

[4] Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, are calculated on an individual investment basis.

[5] See Note 6.

[6] See Note 3.

[7] Includes $(1.4) million related to pipe and equipment purchases and $(1.8) million related to other assets for the year ended December 31, 2017. See Note 6.

[8] Represents distributions paid under WGP’s partnership agreement (see Note 4 and Note 5).

[9] Represents distributions paid to other subsidiaries of Anadarko under WES’s partnership agreement (see Note 4 and Note 5).