Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	$ 7,943
Other comprehensive income before reclassifications	(821)	$ 35
Amounts reclassified from accumulated other comprehensive income	29	22
Other comprehensive (loss) income, net of tax	(792)	57
Balance, end of period	7,451	7,986
Cash	201	142
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(5,055)	(4,647)
Other comprehensive (loss) income, net of tax	(792)	57
Balance, end of period	(5,847)	(4,590)
Pension/Post-Retirement Plans Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(3,512)	(2,953)
Other comprehensive income before reclassifications	109	(59)
Amounts reclassified from accumulated other comprehensive income	29	22
Other comprehensive (loss) income, net of tax	138	(37)
Balance, end of period	(3,374)	(2,990)
Foreign Currency Translation Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(1,543)	(1,694)
Other comprehensive income before reclassifications	(930)	94
Amounts reclassified from accumulated other comprehensive income	0	0
Other comprehensive (loss) income, net of tax	(930)	94
Balance, end of period	$ (2,473)	$ (1,600)