Debt - Debt Activity Table (Detail) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
Feb. 28, 2019	Jun. 30, 2019
Changes in Debt Outstanding [Roll Forward]
Balance at December 31, 2018		$ 16,169
Other, net		27
Balance at June 30, 2019		17,968
Anadarko excluding WES [Member]
Changes in Debt Outstanding [Roll Forward]
Balance at December 31, 2018		11,354
Other, net		25
Balance at June 30, 2019		10,479
Western Midstream Partners, LP [Member]
Changes in Debt Outstanding [Roll Forward]
Balance at December 31, 2018		4,815
Other, net		2
Balance at June 30, 2019		7,489
WES RCF [Member]
Changes in Debt Outstanding [Roll Forward]
Borrowings, credit facility		700
WES RCF [Member] \| Western Midstream Partners, LP [Member]
Changes in Debt Outstanding [Roll Forward]
Borrowings, credit facility		700
WGP RCF [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments, credit facility		(28)
WGP RCF [Member] \| Western Midstream Partners, LP [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments, credit facility		(28)
WES Term Loan Facility [Member]
Changes in Debt Outstanding [Roll Forward]
Borrowings, credit facility		2,000
WES Term Loan Facility [Member] \| Western Midstream Partners, LP [Member]
Changes in Debt Outstanding [Roll Forward]
Borrowings, credit facility	$ 2,000	2,000
8.700 % Senior Notes due 2019 [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments, senior notes		$ (600)
Debt Instrument, Interest Rate, Stated Percentage		8.70%
8.700 % Senior Notes due 2019 [Member] \| Anadarko excluding WES [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments, senior notes		$ (600)
6.950% Senior Notes due 2019 [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments, senior notes		$ (300)
Debt Instrument, Interest Rate, Stated Percentage		6.95%
6.950% Senior Notes due 2019 [Member] \| Anadarko excluding WES [Member]
Changes in Debt Outstanding [Roll Forward]
Repayments, senior notes		$ (300)

Changes in Debt Outstanding [Roll Forward]

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- Definition

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

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- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

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