Accumulated Other Comprehensive Loss - AOCI Activity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 417
Other comprehensive income (loss) before reclassifications	(4)	$ 18
Amounts reclassified from accumulated other comprehensive loss	15	12
Other comprehensive income	11	30
Balance at end of period	504	10,932
Defined Benefit Plan | Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1,045)	(985)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	20	17
Other comprehensive income	20	17
Balance at end of period	(1,025)	(968)
Defined Benefit Plan | Post-Retirement Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	276	308
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	(5)	(5)
Other comprehensive income	(5)	(5)
Balance at end of period	271	303
Foreign Currency Translation Adjustment and Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(41)	(422)
Other comprehensive income (loss) before reclassifications	(4)	18
Amounts reclassified from accumulated other comprehensive loss	0	0
Other comprehensive income	(4)	18
Balance at end of period	(45)	(404)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(810)	(1,099)
Other comprehensive income	11	30
Balance at end of period	$ (799)	$ (1,069)