Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ (10,305)
Other comprehensive (loss)/income before reclassifications	(658)	$ (646)	$ 1,426
Amounts reclassified from AOCI	48	(109)	683
Net current period Other comprehensive (loss)/income	(610)	(755)	2,109
Ending balance	(10,915)	(10,305)
Other comprehensive income (loss), defined benefit plan, gain (loss) arising during period, after tax	(225)	(722)	1,533
Net actuarial (loss)/gain arising during the period, tax	(1)	13	(22)
Other comprehensive (income) loss, defined benefit plan, prior service cost (credit), reclassification adjustment from AOCI, after tax	(92)	(102)	(114)
Amortization of prior service credits included in net periodic pension cost, tax	0	(1)	(2)
Other comprehensive income (loss), defined benefit plan, gain (loss), reclassification adjustment from AOCI, after tax	(105)	2	(791)
Amortization of actuarial loss/(gain) included in net periodic pension cost, tax	0	0	(11)
Gain (loss) on discontinuation of cash flow hedge due to forecasted transaction probable of not occurring, net			39
Loss on discontinuation of cash flow hedge due to forecasted transaction probable of not occurring, tax			(11)
Other comprehensive (income) loss, defined benefit plan, prior service cost (credit), after tax	140		1
Prior service credits arising during the period, tax	0	0	0
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(10,305)	(9,550)	(11,659)
Ending balance	(10,915)	(10,305)	(9,550)
Currency Translation Adjustments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(134)	(167)	(105)
Other comprehensive (loss)/income before reclassifications	(44)	33	(62)
Amounts reclassified from AOCI
Net current period Other comprehensive (loss)/income	(44)	33	(62)
Ending balance	(178)	(134)	(167)
Unrealized Gains and Losses on Certain Investments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	2		1
Other comprehensive (loss)/income before reclassifications		2	(1)
Amounts reclassified from AOCI
Net current period Other comprehensive (loss)/income		2	(1)
Ending balance	2	2
Unrealized Gains and Losses on Derivative Instruments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	12	(24)	6
Other comprehensive (loss)/income before reclassifications	(258)	41	(40)
Amounts reclassified from AOCI	35	(5)	10
Net current period Other comprehensive (loss)/income	(223)	36	(30)
Ending balance	(211)	12	(24)
Defined Benefit Pension Plans & Other Postretirement Benefits
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(10,185)	(9,359)	(11,561)
Other comprehensive (loss)/income before reclassifications	(356)	(722)	1,529
Amounts reclassified from AOCI	13	(104)	673
Net current period Other comprehensive (loss)/income	(343)	(826)	2,202
Ending balance	$ (10,528)	$ (10,185)	$ (9,359)