Other Comprehensive Earnings/Losses (Changes in Each Component of Accumulated Other Comprehensive Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 5,786	$ 14,466	$ 6,319	$ 14,789
Other comprehensive earnings (losses), net of deferred income taxes	(7)	244	(917)	145
Ending balance	3,232	10,637	3,232	10,637
Accumulated Other Comprehensive Losses [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(3,774)	(2,646)	(2,864)	(2,547)
Other comprehensive earnings (losses) before reclassifications	(123)	285	(1,302)	116
Deferred income taxes	41	(65)	279	(28)
Other comprehensive earnings (losses) before reclassifications, net of deferred income taxes	(82)	220	(1,023)	88
Amounts reclassified to net earnings (losses)	99	31	140	78
Deferred income taxes	(24)	(7)	(34)	(21)
Amounts reclassified to net earnings (losses), net of deferred income taxes	75	24	106	57
Other comprehensive earnings (losses), net of deferred income taxes	(7)	244	(917)	145
Ending balance	(3,781)	(2,402)	(3,781)	(2,402)
Benefit Plans [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(2,150)	(2,110)	(2,192)	(2,168)
Other comprehensive earnings (losses) before reclassifications	(75)	0	(75)	0
Deferred income taxes	19	0	19	0
Other comprehensive earnings (losses) before reclassifications, net of deferred income taxes	(56)	0	(56)	0
Amounts reclassified to net earnings (losses)	55	35	111	113
Deferred income taxes	(14)	(9)	(28)	(29)
Amounts reclassified to net earnings (losses), net of deferred income taxes	41	26	83	84
Other comprehensive earnings (losses), net of deferred income taxes	(15)	26	27	84
Ending balance	(2,165)	(2,084)	(2,165)	(2,084)
ABI [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(1,606)	(542)	(693)	(374)
Other comprehensive earnings (losses) before reclassifications	(71)	290	(1,211)	108
Deferred income taxes	22	(67)	260	(28)
Other comprehensive earnings (losses) before reclassifications, net of deferred income taxes	(49)	223	(951)	80
Amounts reclassified to net earnings (losses)	44	(4)	29	(35)
Deferred income taxes	(10)	2	(6)	8
Amounts reclassified to net earnings (losses), net of deferred income taxes	34	(2)	23	(27)
Other comprehensive earnings (losses), net of deferred income taxes	(15)	221	(928)	53
Ending balance	(1,621)	(321)	(1,621)	(321)
Currency Translation Adjustments and Other [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(18)	6	21	(5)
Other comprehensive earnings (losses) before reclassifications	23	(5)	(16)	8
Deferred income taxes	0	2	0	0
Other comprehensive earnings (losses) before reclassifications, net of deferred income taxes	23	(3)	(16)	8
Amounts reclassified to net earnings (losses)	0	0	0	0
Deferred income taxes	0	0	0	0
Amounts reclassified to net earnings (losses), net of deferred income taxes	0	0	0	0
Other comprehensive earnings (losses), net of deferred income taxes	23	(3)	(16)	8
Ending balance	$ 5	$ 3	$ 5	$ 3