Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			$ 7,943
Other comprehensive (loss) income before reclassifications	$ 403	$ (419)	(184)	$ (340)
Amounts reclassified from accumulated other comprehensive income	31	15	91	56
Other comprehensive income (loss), net of tax	434	(404)	(93)	(284)
Balance, end of period	8,752	7,797	8,752	7,797
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(5,582)	(4,527)	(5,055)	(4,647)
Other comprehensive income (loss), net of tax	434	(404)	(93)	(284)
Balance, end of period	(5,148)	(4,931)	(5,148)	(4,931)
Pension/Post-Retirement Plans Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(3,346)	(2,942)	(3,512)	(2,953)
Other comprehensive (loss) income before reclassifications	(94)	56	12	26
Amounts reclassified from accumulated other comprehensive income	31	15	91	56
Other comprehensive income (loss), net of tax	(63)	71	103	82
Balance, end of period	(3,409)	(2,871)	(3,409)	(2,871)
Foreign Currency Translation Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(2,236)	(1,585)	(1,543)	(1,694)
Other comprehensive (loss) income before reclassifications	497	(475)	(196)	(366)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss), net of tax	497	(475)	(196)	(366)
Balance, end of period	$ (1,739)	$ (2,060)	$ (1,739)	$ (2,060)