Segment Information (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Operating_Segments	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments | Operating_Segments		4
Oil and Gas Sales Revenue		$ 3,389,000,000	$ 3,093,000,000	$ 4,945,000,000
Income from Equity Method Investees		102,000,000	90,000,000	170,000,000
Revenues		3,491,000,000	3,183,000,000	5,115,000,000
Exploration Expense		925,000,000	488,000,000	498,000,000
DD&A		2,454,000,000	2,131,000,000	1,759,000,000
Asset Impairments	$ 5,000,000	92,000,000	533,000,000	500,000,000
Goodwill Impairment		0	779,000,000	0
(Gain) Loss on Divestitures		(238,000,000)	0	(73,000,000)
Cash (Received) Paid in Settlement of Commodity Derivative Instruments		139,000,000	(501,000,000)	(976,000,000)
Income (Loss) Before Income Taxes		(1,772,000,000)	(2,219,000,000)	1,710,000,000
Equity Method Investments	453,000,000	400,000,000	453,000,000	325,000,000
Additions to Long-Lived Assets		1,526,000,000	3,062,000,000	5,152,000,000
Goodwill at End of Year (2)	0		0	620,000,000
Total Assets at End of Year	24,196,000,000	21,011,000,000	24,196,000,000	22,518,000,000
Foreign Countries
Segment Reporting Information [Line Items]
Other Revenue, Net		1,000,000,000	1,100,000,000	1,800,000,000
Total Assets at End of Year	3,900,000,000	3,000,000,000	3,900,000,000	4,400,000,000
United States
Segment Reporting Information [Line Items]
Oil and Gas Sales Revenue		2,416,000,000	2,011,000,000	3,189,000,000
Income from Equity Method Investees		52,000,000	51,000,000	9,000,000
Revenues		2,468,000,000	2,062,000,000	3,198,000,000
Exploration Expense		245,000,000	203,000,000	268,000,000
DD&A		2,122,000,000	1,692,000,000	1,318,000,000
Asset Impairments		0	158,000,000	392,000,000
Goodwill Impairment			779,000,000
(Gain) Loss on Divestitures				(34,000,000)
Cash (Received) Paid in Settlement of Commodity Derivative Instruments		126,000,000	(347,000,000)	(604,000,000)
Income (Loss) Before Income Taxes		(1,052,000,000)	(1,553,000,000)	1,150,000,000
Equity Method Investments	226,000,000	183,000,000	226,000,000	82,000,000
Additions to Long-Lived Assets		1,359,000,000	2,534,000,000	4,389,000,000
Goodwill at End of Year (2)	0		0	620,000,000
Total Assets at End of Year	18,831,000,000	17,029,000,000	18,831,000,000	16,365,000,000
West Africa
Segment Reporting Information [Line Items]
Oil and Gas Sales Revenue		433,000,000	580,000,000	1,177,000,000
Income from Equity Method Investees		50,000,000	39,000,000	161,000,000
Revenues		483,000,000	619,000,000	1,338,000,000
Exploration Expense		483,000,000	46,000,000	26,000,000
DD&A		205,000,000	326,000,000	299,000,000
Asset Impairments		0	339,000,000	0
Goodwill Impairment			0
(Gain) Loss on Divestitures				0
Cash (Received) Paid in Settlement of Commodity Derivative Instruments		13,000,000	(154,000,000)	(372,000,000)
Income (Loss) Before Income Taxes		(338,000,000)	(77,000,000)	1,222,000,000
Equity Method Investments	227,000,000	217,000,000	227,000,000	223,000,000
Additions to Long-Lived Assets		54,000,000	124,000,000	261,000,000
Goodwill at End of Year (2)	0		0	0
Total Assets at End of Year	2,299,000,000	1,479,000,000	2,299,000,000	2,763,000,000
Eastern Mediterranean
Segment Reporting Information [Line Items]
Oil and Gas Sales Revenue		540,000,000	497,000,000	479,000,000
Income from Equity Method Investees		0	0	0
Revenues		540,000,000	497,000,000	479,000,000
Exploration Expense		34,000,000	12,000,000	17,000,000
DD&A		81,000,000	70,000,000	63,000,000
Asset Impairments		88,000,000	36,000,000	14,000,000
Goodwill Impairment			0
(Gain) Loss on Divestitures				0
Cash (Received) Paid in Settlement of Commodity Derivative Instruments		0	0	0
Income (Loss) Before Income Taxes		543,000,000	306,000,000	284,000,000
Equity Method Investments	0	0	0	0
Additions to Long-Lived Assets		88,000,000	147,000,000	201,000,000
Goodwill at End of Year (2)	0		0	0
Total Assets at End of Year	2,677,000,000	2,233,000,000	2,677,000,000	2,806,000,000
Other Int'l & Corporate
Segment Reporting Information [Line Items]
Oil and Gas Sales Revenue		0	5,000,000	100,000,000
Income from Equity Method Investees		0	0	0
Revenues		0	5,000,000	100,000,000
Exploration Expense		163,000,000	227,000,000	187,000,000
DD&A		46,000,000	43,000,000	79,000,000
Asset Impairments		4,000,000	0	94,000,000
Goodwill Impairment			0
(Gain) Loss on Divestitures				(39,000,000)
Cash (Received) Paid in Settlement of Commodity Derivative Instruments		0	0	0
Income (Loss) Before Income Taxes		(925,000,000)	(895,000,000)	(946,000,000)
Equity Method Investments	0	0	0	20,000,000
Additions to Long-Lived Assets		25,000,000	257,000,000	301,000,000
Goodwill at End of Year (2)	0		0	0
Total Assets at End of Year	$ 389,000,000	$ 270,000,000	$ 389,000,000	$ 584,000,000