Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			$ 9,260
Other comprehensive (loss) income, net of tax	$ (192)	$ 434	(235)	$ (93)
Balance, end of period	9,888	8,752	9,888	8,752
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(5,153)	(5,582)	(5,110)	(5,055)
Other comprehensive income (loss), before reclassification, net of tax	(231)	403	(350)	(184)
Amounts reclassified from accumulated other comprehensive income	39	31	115	91
Other comprehensive (loss) income, net of tax	(192)	434	(235)	(93)
Balance, end of period	(5,345)	(5,148)	(5,345)	(5,148)
Pension/Post-Retirement Plans Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(4,102)	(3,346)	(4,126)	(3,512)
Other comprehensive income (loss), before reclassification, net of tax	115	(94)	63	12
Amounts reclassified from accumulated other comprehensive income	39	31	115	91
Other comprehensive (loss) income, net of tax	154	(63)	178	103
Balance, end of period	(3,948)	(3,409)	(3,948)	(3,409)
Foreign Currency Translation Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(1,051)	(2,236)	(984)	(1,543)
Other comprehensive income (loss), before reclassification, net of tax	(346)	497	(413)	(196)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive (loss) income, net of tax	(346)	497	(413)	(196)
Balance, end of period	$ (1,397)	$ (1,739)	$ (1,397)	$ (1,739)