Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Revenues			$ 4,438	$ 4,986	$ 4,256
Lease Operating Expense			532
Lease Operating Expense				576	571
Production and Ad Valorem Taxes			175	190	118
Gathering, Transportation and Processing Expense			417	393	432
Other Royalty Expense			13	38	20
Total Production Expense			1,137	1,197	1,141
Exploration Expense			202	129	188
Depreciation, Depletion and Amortization			2,197	1,934	2,053
Loss on Marcellus Shale Upstream Divestiture and Other			0	0	2,379
(Gain) Loss on Divestitures, Net			0	(843)	(326)
Asset Impairments			1,160	206	70
Goodwill Impairment		$ 1,300	0	1,281	0
Clayton Williams Energy Acquisition Expenses			0	0	100
Cost of Purchased Oil and Gas			431	296	0
Firm Transportation Exit Cost			88	0	0
Gain on Asset Retirement Obligation Revision			9	(25)	(42)
Loss (Gain) on Commodity Derivative Instruments			143	(63)	(63)
Loss on Debt Extinguishment	$ 44		44	8	98
(Loss) Income Before Income Taxes			(1,776)	140	(2,191)
Additions to Long Lived Assets, Excluding Acquisitions			2,408	3,253	2,851
Additions to Equity Method Investments			799	0	68
Property, Plant and Equipment, Net	17,451		17,451
Property, Plant and Equipment, Net		18,419		18,419	17,502
Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			3,904	4,461	4,060
Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			2,736	2,945	2,346
NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			354	587	493
Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			814	929	1,221
Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			389	275	0
Cost of Purchased Oil and Gas			85	108	0
Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			51	172	177
Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			94	78	19
Operating Segments | United States
Segment Reporting Information [Line Items]
Total Revenues			3,253	3,590	3,156
Lease Operating Expense			460
Lease Operating Expense				480	466
Production and Ad Valorem Taxes			169	184	115
Gathering, Transportation and Processing Expense			598	533	550
Other Royalty Expense			13	38	20
Total Production Expense			1,240	1,235	1,151
Exploration Expense			57	48	102
Depreciation, Depletion and Amortization			1,907	1,642	1,739
Loss on Marcellus Shale Upstream Divestiture and Other					2,286
(Gain) Loss on Divestitures, Net				36	(325)
Asset Impairments			1,160	169	63
Goodwill Impairment				1,281
Clayton Williams Energy Acquisition Expenses					100
Cost of Purchased Oil and Gas			107	20
Firm Transportation Exit Cost			0
Gain on Asset Retirement Obligation Revision				0	0
Loss (Gain) on Commodity Derivative Instruments			125	(70)	(92)
Loss on Debt Extinguishment			0		0
(Loss) Income Before Income Taxes			(1,431)	(875)	(2,365)
Additions to Long Lived Assets, Excluding Acquisitions			1,651	2,115	1,994
Additions to Equity Method Investments			0
Property, Plant and Equipment, Net	11,859		11,859
Property, Plant and Equipment, Net		13,044		13,044	13,348
Operating Segments | United States | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			3,136	3,570	3,156
Operating Segments | United States | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			2,437	2,548	1,993
Operating Segments | United States | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			354	587	493
Operating Segments | United States | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			345	435	670
Operating Segments | United States | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			109	20
Operating Segments | United States | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			8	0	0
Operating Segments | United States | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Eastern Mediterranean
Segment Reporting Information [Line Items]
Total Revenues			457	480	534
Lease Operating Expense			37
Lease Operating Expense				26	29
Production and Ad Valorem Taxes			0	0	0
Gathering, Transportation and Processing Expense			1	0	0
Other Royalty Expense			0	0	0
Total Production Expense			38	26	29
Exploration Expense			109	7	2
Depreciation, Depletion and Amortization			67	60	76
Loss on Marcellus Shale Upstream Divestiture and Other					0
(Gain) Loss on Divestitures, Net				(376)	(1)
Asset Impairments			0	0	0
Goodwill Impairment				0
Clayton Williams Energy Acquisition Expenses					0
Cost of Purchased Oil and Gas			0	0
Firm Transportation Exit Cost			0
Gain on Asset Retirement Obligation Revision				(8)	0
Loss (Gain) on Commodity Derivative Instruments			0	0	0
Loss on Debt Extinguishment			0		0
(Loss) Income Before Income Taxes			199	742	413
Additions to Long Lived Assets, Excluding Acquisitions			505	671	411
Additions to Equity Method Investments			189
Property, Plant and Equipment, Net	3,041		3,041
Property, Plant and Equipment, Net		2,630		2,630	2,005
Operating Segments | Eastern Mediterranean | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			457	480	534
Operating Segments | Eastern Mediterranean | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			6	7	6
Operating Segments | Eastern Mediterranean | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Eastern Mediterranean | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			451	473	528
Operating Segments | Eastern Mediterranean | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			0	0
Operating Segments | Eastern Mediterranean | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Eastern Mediterranean | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | West Africa
Segment Reporting Information [Line Items]
Total Revenues			372	543	490
Lease Operating Expense			76
Lease Operating Expense				97	90
Production and Ad Valorem Taxes			0	0	0
Gathering, Transportation and Processing Expense			0	0	0
Other Royalty Expense			0	0	0
Total Production Expense			76	97	90
Exploration Expense			13	6	5
Depreciation, Depletion and Amortization			83	115	146
Loss on Marcellus Shale Upstream Divestiture and Other					0
(Gain) Loss on Divestitures, Net				0	0
Asset Impairments			0	0	0
Goodwill Impairment				0
Clayton Williams Energy Acquisition Expenses					0
Cost of Purchased Oil and Gas			0	0
Firm Transportation Exit Cost			0
Gain on Asset Retirement Obligation Revision				0	0
Loss (Gain) on Commodity Derivative Instruments			18	7	29
Loss on Debt Extinguishment			0		0
(Loss) Income Before Income Taxes			164	305	203
Additions to Long Lived Assets, Excluding Acquisitions			70	12	34
Additions to Equity Method Investments			0
Property, Plant and Equipment, Net	793		793
Property, Plant and Equipment, Net		805		805	863
Operating Segments | West Africa | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			311	411	370
Operating Segments | West Africa | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			293	390	347
Operating Segments | West Africa | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | West Africa | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			18	21	23
Operating Segments | West Africa | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			0	0
Operating Segments | West Africa | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			61	132	120
Operating Segments | West Africa | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Other Int'l
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Lease Operating Expense			0
Lease Operating Expense				0	0
Production and Ad Valorem Taxes			0	0	0
Gathering, Transportation and Processing Expense			0	0	0
Other Royalty Expense			0	0	0
Total Production Expense			0	0	0
Exploration Expense			23	68	79
Depreciation, Depletion and Amortization			1	2	4
Loss on Marcellus Shale Upstream Divestiture and Other					0
(Gain) Loss on Divestitures, Net				0	0
Asset Impairments			0	0	7
Goodwill Impairment				0
Clayton Williams Energy Acquisition Expenses					0
Cost of Purchased Oil and Gas			0	0
Firm Transportation Exit Cost			0
Gain on Asset Retirement Obligation Revision				(17)	(42)
Loss (Gain) on Commodity Derivative Instruments			0	0	0
Loss on Debt Extinguishment			0		0
(Loss) Income Before Income Taxes			(25)	(53)	(54)
Additions to Long Lived Assets, Excluding Acquisitions			20	0	(34)
Additions to Equity Method Investments			0
Property, Plant and Equipment, Net	44		44
Property, Plant and Equipment, Net		37		37	25
Operating Segments | Other Int'l | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Other Int'l | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Other Int'l | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Other Int'l | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Other Int'l | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			0	0
Operating Segments | Other Int'l | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Operating Segments | Other Int'l | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Noble Midstream Partners | Midstream
Segment Reporting Information [Line Items]
Total Revenues			693	611	353
Lease Operating Expense			4
Lease Operating Expense				0	0
Production and Ad Valorem Taxes			6	6	3
Gathering, Transportation and Processing Expense			110	95	70
Other Royalty Expense			0	0	0
Total Production Expense			120	101	73
Exploration Expense			0	0	0
Depreciation, Depletion and Amortization			104	87	30
Loss on Marcellus Shale Upstream Divestiture and Other					0
(Gain) Loss on Divestitures, Net				(503)	0
Asset Impairments			0	37	0
Goodwill Impairment				0
Clayton Williams Energy Acquisition Expenses					0
Cost of Purchased Oil and Gas			181	136
Firm Transportation Exit Cost			0
Gain on Asset Retirement Obligation Revision				0	0
Loss (Gain) on Commodity Derivative Instruments			0	0	0
Loss on Debt Extinguishment			0		0
(Loss) Income Before Income Taxes			258	726	233
Additions to Long Lived Assets, Excluding Acquisitions			230	521	423
Additions to Equity Method Investments			610
Property, Plant and Equipment, Net	1,721		1,721
Property, Plant and Equipment, Net		1,742		1,742	1,027
Noble Midstream Partners | Midstream | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Noble Midstream Partners | Midstream | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Noble Midstream Partners | Midstream | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Noble Midstream Partners | Midstream | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Noble Midstream Partners | Midstream | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			190	142
Noble Midstream Partners | Midstream | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			(18)	40	57
Noble Midstream Partners | Midstream | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			94	78	19
Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Total Revenues			(427)	(351)	(277)
Lease Operating Expense			(45)
Lease Operating Expense				(27)	(14)
Production and Ad Valorem Taxes			0	0	0
Gathering, Transportation and Processing Expense			(292)	(235)	(188)
Other Royalty Expense			0	0	0
Total Production Expense			(337)	(262)	(202)
Exploration Expense			0	0	0
Depreciation, Depletion and Amortization			(29)	(20)	(5)
Loss on Marcellus Shale Upstream Divestiture and Other					0
(Gain) Loss on Divestitures, Net				0	0
Asset Impairments			0	0	0
Goodwill Impairment				0
Clayton Williams Energy Acquisition Expenses					0
Cost of Purchased Oil and Gas			0	0
Firm Transportation Exit Cost			0
Gain on Asset Retirement Obligation Revision				0	0
Loss (Gain) on Commodity Derivative Instruments			0	0	0
Loss on Debt Extinguishment			0		0
(Loss) Income Before Income Taxes			(55)	(60)	(62)
Additions to Long Lived Assets, Excluding Acquisitions			(92)	(91)	(79)
Additions to Equity Method Investments			0
Property, Plant and Equipment, Net	(223)		(223)
Property, Plant and Equipment, Net		(145)		(145)	(74)
Intersegment Eliminations and Other | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Intersegment Eliminations and Other | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Intersegment Eliminations and Other | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Intersegment Eliminations and Other | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Intersegment Eliminations and Other | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			0	0
Intersegment Eliminations and Other | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Intersegment Eliminations and Other | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues				0	0
Corporate
Segment Reporting Information [Line Items]
Total Revenues			90	113	0
Lease Operating Expense			0
Lease Operating Expense				0	0
Production and Ad Valorem Taxes			0	0	0
Gathering, Transportation and Processing Expense			0	0	0
Other Royalty Expense			0	0	0
Total Production Expense			0	0	0
Exploration Expense			0	0	0
Depreciation, Depletion and Amortization			64	48	63
Loss on Marcellus Shale Upstream Divestiture and Other					93
(Gain) Loss on Divestitures, Net				0	0
Asset Impairments			0	0	0
Goodwill Impairment				0
Clayton Williams Energy Acquisition Expenses					0
Cost of Purchased Oil and Gas			143	140
Firm Transportation Exit Cost			88
Gain on Asset Retirement Obligation Revision				0	0
Loss (Gain) on Commodity Derivative Instruments			0	0	0
Loss on Debt Extinguishment			44		98
(Loss) Income Before Income Taxes			(886)	(645)	(559)
Additions to Long Lived Assets, Excluding Acquisitions			24	25	102
Additions to Equity Method Investments			0
Property, Plant and Equipment, Net	$ 216		216
Property, Plant and Equipment, Net		$ 306		306	308
Corporate | Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Corporate | Crude Oil Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Corporate | NGL Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Corporate | Natural Gas Sales
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Corporate | Sales of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Total Revenues			90	113
Corporate | Income (Loss) from Equity Method Investments and Other
Segment Reporting Information [Line Items]
Total Revenues			0	0	0
Corporate | Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Total Revenues			$ 0	$ 0	$ 0