Segment Information - Operating Results by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenue from Sales	$ 1,052	$ 1,286
Lease Operating Expense	151	155
Production and Ad Valorem Taxes	49	54
Gathering, Transportation and Processing Expense	102	93
Marcellus Shale Exit Cost	92
Total	305	319
Depreciation, Depletion and Amortization	508	468
Gain on Divestitures, Net	0	(588)
Asset Impairments		168
Loss on Commodity Derivative Instruments	212	79
(Loss) Income Before Income Taxes	(373)	543
Additions to Long-Lived Assets, Excluding Acquisitions	712	905
Investments in Equity Method Investees	271	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	(106)	(81)
Lease Operating Expense	(9)	0
Production and Ad Valorem Taxes	0	0
Gathering, Transportation and Processing Expense	(69)	(53)
Marcellus Shale Exit Cost	0
Total	(78)	(53)
Depreciation, Depletion and Amortization	(7)	(3)
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Commodity Derivative Instruments	0	0
(Loss) Income Before Income Taxes	(14)	(15)
Additions to Long-Lived Assets, Excluding Acquisitions	(23)	(32)
Investments in Equity Method Investees	0
Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	27	31
Lease Operating Expense	0	0
Production and Ad Valorem Taxes	0	0
Gathering, Transportation and Processing Expense	0	0
Marcellus Shale Exit Cost	92
Total	0	0
Depreciation, Depletion and Amortization	15	11
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Commodity Derivative Instruments	0	0
(Loss) Income Before Income Taxes	(264)	(174)
Additions to Long-Lived Assets, Excluding Acquisitions	11	10
Investments in Equity Method Investees	0
United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	763	948
Lease Operating Expense	125	126
Production and Ad Valorem Taxes	47	53
Gathering, Transportation and Processing Expense	142	128
Marcellus Shale Exit Cost	0
Total	317	324
Depreciation, Depletion and Amortization	439	404
Gain on Divestitures, Net		(6)
Asset Impairments		168
Loss on Commodity Derivative Instruments	188	64
(Loss) Income Before Income Taxes	(247)	(43)
Additions to Long-Lived Assets, Excluding Acquisitions	511	534
Investments in Equity Method Investees	0
United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	165	128
Lease Operating Expense	1	0
Production and Ad Valorem Taxes	2	1
Gathering, Transportation and Processing Expense	29	20
Marcellus Shale Exit Cost	0
Total	32	21
Depreciation, Depletion and Amortization	25	17
Gain on Divestitures, Net		(196)
Asset Impairments		0
Loss on Commodity Derivative Instruments	0	0
(Loss) Income Before Income Taxes	73	247
Additions to Long-Lived Assets, Excluding Acquisitions	66	242
Investments in Equity Method Investees	271
United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	106	81
Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	118	131
Lease Operating Expense	10	7
Production and Ad Valorem Taxes	0	0
Gathering, Transportation and Processing Expense	0	0
Marcellus Shale Exit Cost	0
Total	10	7
Depreciation, Depletion and Amortization	16	13
Gain on Divestitures, Net		(386)
Asset Impairments		0
Loss on Commodity Derivative Instruments	0	0
(Loss) Income Before Income Taxes	84	473
Additions to Long-Lived Assets, Excluding Acquisitions	132	147
Investments in Equity Method Investees	0
West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	85	129
Lease Operating Expense	24	22
Production and Ad Valorem Taxes	0	0
Gathering, Transportation and Processing Expense	0	0
Marcellus Shale Exit Cost	0
Total	24	22
Depreciation, Depletion and Amortization	20	26
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Commodity Derivative Instruments	24	15
(Loss) Income Before Income Taxes	11	64
Additions to Long-Lived Assets, Excluding Acquisitions	5	2
Investments in Equity Method Investees	0
Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Lease Operating Expense	0	0
Production and Ad Valorem Taxes	0	0
Gathering, Transportation and Processing Expense	0	0
Marcellus Shale Exit Cost	0
Total	0	0
Depreciation, Depletion and Amortization	0	0
Gain on Divestitures, Net		0
Asset Impairments		0
Loss on Commodity Derivative Instruments	0	0
(Loss) Income Before Income Taxes	(16)	(9)
Additions to Long-Lived Assets, Excluding Acquisitions	10	2
Investments in Equity Method Investees	0
Oil, NGL and Gas Sales
Segment Reporting Information [Line Items]
Revenue from Sales	937	1,173
Oil, NGL and Gas Sales | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Oil, NGL and Gas Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Oil, NGL and Gas Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	749	948
Oil, NGL and Gas Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Oil, NGL and Gas Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	118	131
Oil, NGL and Gas Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	70	94
Oil, NGL and Gas Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Crude Oil Sales
Segment Reporting Information [Line Items]
Revenue from Sales	612	773
Crude Oil Sales | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Crude Oil Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Crude Oil Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	545	682
Crude Oil Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Crude Oil Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	1	2
Crude Oil Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	66	89
Crude Oil Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
NGL Sales
Segment Reporting Information [Line Items]
Revenue from Sales	96	146
NGL Sales | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
NGL Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
NGL Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	96	146
NGL Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
NGL Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
NGL Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
NGL Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Natural Gas Sales
Segment Reporting Information [Line Items]
Revenue from Sales	229	254
Natural Gas Sales | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Natural Gas Sales | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Natural Gas Sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	108	120
Natural Gas Sales | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Natural Gas Sales | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	117	129
Natural Gas Sales | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	4	5
Natural Gas Sales | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Cost of Purchased of Gas
Segment Reporting Information [Line Items]
Revenue from Sales	74	53
Costs and Expenses	87	57
Cost of Purchased of Gas | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Cost of Purchased of Gas | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	27	31
Costs and Expenses	27	30
Cost of Purchased of Gas | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	14	0
Cost of Purchased of Gas | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	33	22
Cost of Purchased of Gas | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Cost of Purchased of Gas | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Cost of Purchased of Gas | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Cost of Purchased Oil and Gas
Segment Reporting Information [Line Items]
Costs and Expenses	87	57
Cost of Purchased Oil and Gas | Intersegment Eliminations
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Cost of Purchased Oil and Gas | Corporate
Segment Reporting Information [Line Items]
Costs and Expenses	42	36
Cost of Purchased Oil and Gas | United States | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	14	0
Cost of Purchased Oil and Gas | United States | Noble Midstream
Segment Reporting Information [Line Items]
Costs and Expenses	31	21
Cost of Purchased Oil and Gas | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Cost of Purchased Oil and Gas | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Cost of Purchased Oil and Gas | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Income from Equity Method Investees and Other
Segment Reporting Information [Line Items]
Revenue from Sales	17	47
Income from Equity Method Investees and Other | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Income from Equity Method Investees and Other | Corporate
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Income from Equity Method Investees and Other | United States | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Income from Equity Method Investees and Other | United States | Noble Midstream
Segment Reporting Information [Line Items]
Revenue from Sales	2	12
Income from Equity Method Investees and Other | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Income from Equity Method Investees and Other | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	15	35
Income from Equity Method Investees and Other | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Revenue from Sales	0	0
Midstream Services Revenues – Third Party
Segment Reporting Information [Line Items]
Revenue from Sales	24	13
Midstream Services Revenues – Third Party | Intersegment Eliminations
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	24	13
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]
Costs and Expenses	3	17
Other Royalty Expense | Intersegment Eliminations
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Other Royalty Expense | Corporate
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Other Royalty Expense | United States | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	3	17
Other Royalty Expense | United States | Noble Midstream
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Other Royalty Expense | Eastern Mediterranean | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Other Royalty Expense | West Africa | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	0	0
Other Royalty Expense | Other Int'l | Operating Segments
Segment Reporting Information [Line Items]
Costs and Expenses	$ 0	$ 0