SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Detail)	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) $ / MMBTU	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2015 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments	$ 639,000,000	$ 49,000,000	$ 21,000,000	$ 16,000,000	$ 32,000,000	$ 160,000,000	$ 39,000,000	$ 23,000,000	$ 511,000,000	$ 8,000,000	$ 1,103,000,000
Capitalized exploratory well costs, impairment									10,000,000
Impairment on equity method investment									113,000,000
Inventory write-downs									4,000,000		$ 55,000,000
UK Petroleum Revenue Tax (PRT) rate										0.00%	35.00%
Impairment charge of Petroleum Revenue Tax benefits, before tax											$ 486,000,000
Cash and cash equivalents	714,000,000				1,668,000,000				714,000,000	$ 1,668,000,000	1,377,000,000		$ 1,467,000,000
Restricted cash	0				0				0	0
Allowance for doubtful accounts	92,000,000				84,000,000				92,000,000	84,000,000	93,000,000		$ 103,000,000
Oil and gas property impaired, fair value	323,000,000				306,000,000				323,000,000	306,000,000
Gathering, transmission and processing facilities	1,856,000,000				1,376,000,000				1,856,000,000	1,376,000,000
Accumulated depreciation	28,335,000,000				25,643,000,000				28,335,000,000	25,643,000,000
Impairment of GTP assets									56,000,000	0	135,000,000
Fair value of GTP assets											142,000,000
Gain (loss) on sale of oil and gas properties											21,000,000
Property and equipment, net	18,421,000,000				17,759,000,000				18,421,000,000	17,759,000,000	18,867,000,000
Accounts payable									66,000,000	76,000,000
Oil and gas production revenues									7,348,000,000	5,887,000,000	5,367,000,000
Cost of oil and gas purchased									$ 348,000,000	195,000,000	200,000,000
Maximum percentage of production available to contract partners									40.00%
Oil and gas production revenues, excluding assessed tax									$ 7,100,000,000
Revenue from non-customers									652,000,000
Receivables from contracts with customers, net of allowance for doubtful accounts	1,000,000,000				1,100,000,000				1,000,000,000	1,100,000,000
Other foreign currency losses									1,000,000	11,000,000	$ 25,000,000
North Sea
Schedule Of Significant Accounting Policies [Line Items]
Gain (loss) on sale of oil and gas properties										6,000,000
Scottish Area Gas Evacuation System | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage											30.28%
Beryl Pipeline | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage											60.56%
Oil and Gas Properties, Proved
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									328,000,000	0	$ 427,000,000
GTC facilities
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									56,000,000		135,000,000
Gathering, transmission and processing facilities	1,900,000,000				1,400,000,000				1,900,000,000	1,400,000,000
Accumulated depreciation	264,000,000				194,000,000				264,000,000	194,000,000
Gain (loss) on sale of oil and gas properties									0		0
Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Accumulated depreciation	786,000,000				739,000,000				786,000,000	739,000,000
Property and equipment, net	$ 1,100,000,000				1,000,000,000				$ 1,100,000,000	1,000,000,000
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Voting interest required for consolidation of investments	50.00%								50.00%
Minimum | Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Useful lives of gas gathering, transmission and processing facilities									3 years
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Voting interest required for consolidation of investments	50.00%								50.00%
Maximum | Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Useful lives of gas gathering, transmission and processing facilities									20 years
Oil and Gas, Purchased
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas production revenues									$ 357,000,000	248,000,000	152,000,000
Cost of oil and gas purchased									340,000,000	254,000,000	$ 159,000,000
ALTM
Schedule Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 450,000,000								450,000,000
Gathering, transmission and processing facilities	$ 1,300,000,000				$ 705,000,000				$ 1,300,000,000	$ 705,000,000
Apache Egypt | Sinopec
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners	33.33%								33.33%
ALTM
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners	21.00%								21.00%
Crude Oil | Dated Brent | Minimum
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas pricing formula sliding scale (in dollars per MMBtu) | $ / MMBTU									1.50
Crude Oil | Dated Brent | Maximum
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas pricing formula sliding scale (in dollars per MMBtu) | $ / MMBTU									2.65
Scenario, Forecast | Accounting Standards Update 2016-02 | Minimum
Schedule Of Significant Accounting Policies [Line Items]
Lease right-of-use assets												$ 350,000,000
Lease liabilities												350,000,000
Scenario, Forecast | Accounting Standards Update 2016-02 | Maximum
Schedule Of Significant Accounting Policies [Line Items]
Lease right-of-use assets												400,000,000
Lease liabilities												$ 400,000,000