Basis Of Presentation (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2015
Basis of Presentation [Line Items]
Net earnings		$ 2,363	$ 1,810	$ 7,036	$ 5,138
Increase/(Decrease) in revenue due to change in accounting estimate		(59)	(44)	(14)	426
Increase/(Decrease) in Earnings from operations due to change in accounting estimate		$ (155)	$ (215)	$ (314)	$ 207
Change in Earnings Per Share Due to Change in Accounting Estimate		$ (0.30)	$ (0.25)	$ (0.50)	$ 0.24
Retained earnings		$ 54,666		$ 54,666		$ 49,618
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	$ (15,949)	$ (13,036)	$ (15,949)	$ (13,036)	(16,373)	$ (13,623)	$ (16,139)	$ (13,234)
Accounting Standards Update 2014-09 [Member]
Basis of Presentation [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption						1,301	139			$ 901
Net earnings						261	$ 139
Adjustments for New Accounting Pronouncement [Member]
Basis of Presentation [Line Items]
Net earnings			$ (43)		$ 73
Retained earnings						4,298
Accumulated Other Comprehensive Income (Loss), Net of Tax						(2,997)
Accounting Standards Update 2018-02 [Member]
Basis of Presentation [Line Items]
Retained earnings						2,997
Accumulated Other Comprehensive Income (Loss), Net of Tax						(2,997)
Retained Earnings [Member] | Accounting Standards Update 2014-09 [Member]
Basis of Presentation [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption						$ 1,301				$ 901

[1] Net of tax.