Segment Information - Operating Results by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenue from Sales	$ 4,986	$ 4,256	$ 3,491
Lease Operating Expense	576	571	542
Production and Ad Valorem Taxes	190	118	57
Gathering, Transportation and Processing Expense	393	432	480
Total	1,197	1,141	1,100
Exploration Expense	129	188	925
DD&A	1,934	2,053	2,454
(Gain) Loss on Divestitures, Net	206
Goodwill Impairment	1,281	0	0
Asset Impairments	(843)	(326)	(238)
Gain on Asset Retirement Obligation Revisions	(25)	(42)
Gain on Divestitures, Net	0	100	0
Asset Impairments	8	98	(80)
Loss on Marcellus Shale Upstream Divestiture and Other	0	2,379	0
Asset Impairments	206	70	92
(Gain) Loss on Commodity Derivative Instruments	(63)	(63)	139
Income (Loss) Before Income Taxes	140	(2,191)	(1,772)
Additions to Long-Lived Assets	3,253	2,851	1,526
Property, Plant and Equipment, Net	18,419	17,502	18,548
Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	(351)	(277)	(200)
Lease Operating Expense	(27)	(14)	(18)
Production and Ad Valorem Taxes	0	0	0
Gathering, Transportation and Processing Expense	(235)	(188)	(128)
Total	(262)	(202)	(146)
Exploration Expense	0	0	0
DD&A	(20)	(5)	0
(Gain) Loss on Divestitures, Net	0
Goodwill Impairment	0
Asset Impairments	0	0	0
Gain on Asset Retirement Obligation Revisions	0	0
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Marcellus Shale Upstream Divestiture and Other		0
Asset Impairments		0	0
(Gain) Loss on Commodity Derivative Instruments	0	0	0
Income (Loss) Before Income Taxes	(60)	(62)	(51)
Additions to Long-Lived Assets	(91)	(79)	(53)
Property, Plant and Equipment, Net	(145)	(74)	0
Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	113	0	0
Lease Operating Expense	0	0	0
Production and Ad Valorem Taxes	0	0	0
Gathering, Transportation and Processing Expense	0	0	0
Total	0	0	0
Exploration Expense	0	0	0
DD&A	48	63	40
(Gain) Loss on Divestitures, Net	0
Goodwill Impairment	0
Asset Impairments	0	0	0
Gain on Asset Retirement Obligation Revisions	0	0
Gain on Divestitures, Net		0
Asset Impairments		98
Loss on Marcellus Shale Upstream Divestiture and Other		93
Asset Impairments		0	0
(Gain) Loss on Commodity Derivative Instruments	0	0	0
Income (Loss) Before Income Taxes	(645)	(559)	(626)
Additions to Long-Lived Assets	25	102	32
Property, Plant and Equipment, Net	306	308	332
United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	3,590	3,156	2,416
Lease Operating Expense	480	466	418
Production and Ad Valorem Taxes	184	115	55
Gathering, Transportation and Processing Expense	533	550	564
Total	1,235	1,151	1,058
Exploration Expense	48	102	245
DD&A	1,642	1,739	2,103
(Gain) Loss on Divestitures, Net	169
Goodwill Impairment	1,281
Asset Impairments	36	(325)	23
Gain on Asset Retirement Obligation Revisions	0	0
Gain on Divestitures, Net		100
Asset Impairments		0
Loss on Marcellus Shale Upstream Divestiture and Other		2,286
Asset Impairments		63	0
(Gain) Loss on Commodity Derivative Instruments	(70)	(92)	126
Income (Loss) Before Income Taxes	(875)	(2,365)	(1,277)
Additions to Long-Lived Assets	2,115	1,994	1,353
Property, Plant and Equipment, Net	13,044	13,348	14,755
United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	611	353	252
Lease Operating Expense	0	0	0
Production and Ad Valorem Taxes	6	3	2
Gathering, Transportation and Processing Expense	95	70	44
Total	101	73	46
Exploration Expense	0	0	0
DD&A	87	30	19
(Gain) Loss on Divestitures, Net	37
Goodwill Impairment	0
Asset Impairments	(503)	0	0
Gain on Asset Retirement Obligation Revisions	0	0
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Marcellus Shale Upstream Divestiture and Other		0
Asset Impairments		0	0
(Gain) Loss on Commodity Derivative Instruments	0	0	0
Income (Loss) Before Income Taxes	726	233	176
Additions to Long-Lived Assets	521	423	58
Property, Plant and Equipment, Net	1,742	1,027	594
United States | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	351	277	200
Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	480	534	540
Lease Operating Expense	26	29	37
Production and Ad Valorem Taxes	0	0	0
Gathering, Transportation and Processing Expense	0	0	0
Total	26	29	37
Exploration Expense	7	2	34
DD&A	60	76	81
(Gain) Loss on Divestitures, Net	0
Goodwill Impairment	0
Asset Impairments	(376)	(1)	(261)
Gain on Asset Retirement Obligation Revisions	(8)	0
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Marcellus Shale Upstream Divestiture and Other		0
Asset Impairments		0	88
(Gain) Loss on Commodity Derivative Instruments	0	0	0
Income (Loss) Before Income Taxes	742	413	543
Additions to Long-Lived Assets	671	411	88
Property, Plant and Equipment, Net	2,630	2,005	1,872
West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	543	490	483
Lease Operating Expense	97	90	105
Production and Ad Valorem Taxes	0	0	0
Gathering, Transportation and Processing Expense	0	0	0
Total	97	90	105
Exploration Expense	6	5	483
DD&A	115	146	205
(Gain) Loss on Divestitures, Net	0
Goodwill Impairment	0
Asset Impairments	0	0	0
Gain on Asset Retirement Obligation Revisions	0	0
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Marcellus Shale Upstream Divestiture and Other		0
Asset Impairments		0	0
(Gain) Loss on Commodity Derivative Instruments	7	29	13
Income (Loss) Before Income Taxes	305	203	(338)
Additions to Long-Lived Assets	12	34	54
Property, Plant and Equipment, Net	805	863	980
Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Lease Operating Expense	0	0	0
Production and Ad Valorem Taxes	0	0	0
Gathering, Transportation and Processing Expense	0	0	0
Total	0	0	0
Exploration Expense	68	79	163
DD&A	2	4	6
(Gain) Loss on Divestitures, Net	0
Goodwill Impairment	0
Asset Impairments	0	0	0
Gain on Asset Retirement Obligation Revisions	(17)	(42)
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Marcellus Shale Upstream Divestiture and Other		0
Asset Impairments		7	4
(Gain) Loss on Commodity Derivative Instruments	0	0	0
Income (Loss) Before Income Taxes	(53)	(54)	(199)
Additions to Long-Lived Assets	0	(34)	(6)
Property, Plant and Equipment, Net	37	25	15
Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Revenue from Sales	4,461	4,060	3,389
Oil, NGL and Gas Sales | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Oil, NGL and Gas Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Oil, NGL and Gas Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	3,570	3,156	2,416
Oil, NGL and Gas Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Oil, NGL and Gas Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	480	534	540
Oil, NGL and Gas Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	411	370	433
Oil, NGL and Gas Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Crude Oil Sales
Segment Reporting Information [Line Items]
Revenue from Sales	2,945	2,346	1,854
Crude Oil Sales | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Crude Oil Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Crude Oil Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	2,548	1,993	1,439
Crude Oil Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Crude Oil Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	7	6	5
Crude Oil Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	390	347	410
Crude Oil Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
NGL Sales
Segment Reporting Information [Line Items]
Revenue from Sales	587	493	296
NGL Sales | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
NGL Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
NGL Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	587	493	296
NGL Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
NGL Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
NGL Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
NGL Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Natural Gas Sales
Segment Reporting Information [Line Items]
Revenue from Sales	929	1,221	1,239
Natural Gas Sales | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Natural Gas Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Natural Gas Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	435	670	681
Natural Gas Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Natural Gas Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	473	528	535
Natural Gas Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	21	23	23
Natural Gas Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Purchased Oil and Gas
Segment Reporting Information [Line Items]
Revenue from Sales	275	0	0
Cost of Goods and Services Sold	296
Purchased Oil and Gas | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0
Cost of Goods and Services Sold	0
Purchased Oil and Gas | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	113
Cost of Goods and Services Sold	140
Purchased Oil and Gas | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	20
Cost of Goods and Services Sold	20
Purchased Oil and Gas | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	142
Cost of Goods and Services Sold	136
Purchased Oil and Gas | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0
Cost of Goods and Services Sold	0
Purchased Oil and Gas | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0
Cost of Goods and Services Sold	0
Purchased Oil and Gas | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0
Cost of Goods and Services Sold	0
Income from Equity Method Investees
Segment Reporting Information [Line Items]
Revenue from Sales	172	177	102
Income from Equity Method Investees | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Income from Equity Method Investees | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Income from Equity Method Investees | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Income from Equity Method Investees | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	40	57	52
Income from Equity Method Investees | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Income from Equity Method Investees | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	132	120	50
Income from Equity Method Investees | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0	0
Midstream Services Revenues - Third Party
Segment Reporting Information [Line Items]
Revenue from Sales	78	19	0
Midstream Services Revenues - Third Party | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Midstream Services Revenues - Third Party | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Midstream Services Revenues - Third Party | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Midstream Services Revenues - Third Party | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	78	19
Midstream Services Revenues - Third Party | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Midstream Services Revenues - Third Party | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Midstream Services Revenues - Third Party | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Other Royalty Expense
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	38	20	21
Other Royalty Expense | Intersegment Eliminations and Other
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	0	0	0
Other Royalty Expense | Corporate
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	0	0	0
Other Royalty Expense | United States | Operating Segments
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	38	20	21
Other Royalty Expense | United States | Noble Midstream
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	0	0	0
Other Royalty Expense | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	0	0	0
Other Royalty Expense | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	0	0	0
Other Royalty Expense | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Cost of Goods and Services Sold	$ 0	$ 0	$ 0