Supplemental Quarterly Financial Information (Schedule Of Financial Statements Changes to the Consolidated Statement of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	[1]	Dec. 31, 2015	[1]
Quarterly Financial Data [Line Items]
Net earnings					$ 1,078	$ (1,458)		$ (13,645)
Depreciation, depletion and amortization					2,074	2,096		4,022
Exploratory dry hole expense and unproved leasehold impairments					219	113		248
Gains and losses on asset sales					(217)	(1,483)		7
Deferred income tax expense (benefit)					(294)	41		(5,976)
Share-based compensation					198	233		244
Other					(122)	270		312
Net cash from operating activities					2,909	1,500		4,898
Capital expenditures					(2,759)	(2,047)		(4,787)
Divestitures of property and equipment					417	3,113		107
Net cash from investing activities					$ (2,210)	$ (594)		$ (5,803)
As Reported Under Sucessful Efforts
Quarterly Financial Data [Line Items]
Net earnings	$ 304	$ 212	$ 245	$ 317
Depreciation, depletion and amortization	528	512	506	528
Exploratory dry hole expense and unproved leasehold impairments	139
Gains and losses on asset sales	(18)
Deferred income tax expense (benefit)	(245)
Share-based compensation	47
Other	16
Net cash from operating activities	725	700	738	746
Capital expenditures	(799)
Divestitures of property and equipment	101
Net cash from investing activities	(712)	$ (457)	$ (587)	$ (454)
Under Full Cost [Member]
Quarterly Financial Data [Line Items]
Net earnings	594
Depreciation, depletion and amortization	417
Gains and losses on asset sales	1
Deferred income tax expense (benefit)	(232)
Share-based compensation	36
Other	26
Net cash from operating activities	796
Capital expenditures	(871)
Divestitures of property and equipment	102
Net cash from investing activities	(783)
Changes [Member]
Quarterly Financial Data [Line Items]
Net earnings	(290)
Depreciation, depletion and amortization	111
Exploratory dry hole expense and unproved leasehold impairments	139
Gains and losses on asset sales	(19)
Deferred income tax expense (benefit)	(13)
Share-based compensation	11
Other	(10)
Net cash from operating activities	(71)
Capital expenditures	72
Divestitures of property and equipment	(1)
Net cash from investing activities	$ 71

[1] Prior year amounts have been recast due to change in accounting principle. See Note 2 in “Item 8. Financial Statements and Supplementary Data” of this report.