Accumulated Other Comprehensive Loss - AOCI Activity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period			$ 11,840
Other comprehensive income (loss) before reclassifications			(245)	$ 29
Amounts reclassified from accumulated other comprehensive loss			201	207
Other comprehensive income (loss)	$ 15	$ 133	(44)	236
Balance at end of period	12,577	11,183	12,577	11,183
Defined Benefit Plan | Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period			(1,577)	(2,197)
Other comprehensive income (loss) before reclassifications			0	133
Amounts reclassified from accumulated other comprehensive loss			68	149
Other comprehensive income (loss)			68	282
Balance at end of period	(1,509)	(1,915)	(1,509)	(1,915)
Defined Benefit Plan | Post-Retirement Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period			(164)	(272)
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive loss			4	11
Other comprehensive income (loss)			4	11
Balance at end of period	(160)	(261)	(160)	(261)
Foreign Currency Translation Adjustment and Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period			(400)	(265)
Other comprehensive income (loss) before reclassifications			(245)	(103)
Amounts reclassified from accumulated other comprehensive loss			112	0
Other comprehensive income (loss)			(133)	(103)
Balance at end of period	(533)	(368)	(533)	(368)
Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period			(17)	(79)
Other comprehensive income (loss) before reclassifications			0	(1)
Amounts reclassified from accumulated other comprehensive loss			17	47
Other comprehensive income (loss)			17	46
Balance at end of period	0	(33)	0	(33)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(2,217)	(2,710)	(2,158)	(2,813)
Other comprehensive income (loss)	15	133	(44)	236
Balance at end of period	$ (2,202)	$ (2,577)	$ (2,202)	$ (2,577)