Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ (11,659)
Other comprehensive income/(loss) before reclassifications	1,426	$ 4,248	$ (1,817)
Amounts reclassified from AOCI	683	1,226	837
Net current period Other comprehensive income/(loss)	2,109	5,474	(980)
Ending balance	(9,550)	(11,659)
Other comprehensive income (loss), defined benefit plan, gain (loss) arising during period, after tax	1,533	4,262	(1,956)
Net actuarial gain/(loss) arising during the period, tax	(22)	(32)	111
Other comprehensive income (loss), defined benefit plan, gain (loss), reclassification adjustment from AOCI, after tax	791	1,155	917
Amortization of actuarial loss included in net periodic pension cost, tax	(11)	(8)	(52)
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)
Currency Translation Adjustments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(105)	(30)	(128)
Other comprehensive income/(loss) before reclassifications	(62)	(75)	98
Net current period Other comprehensive income/(loss)	(62)	(75)	98
Ending balance	(167)	(105)	(30)
Unrealized Gains and Losses on Certain Investments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	1	1	1
Other comprehensive income/(loss) before reclassifications	(1)
Net current period Other comprehensive income/(loss)	(1)
Ending balance		1	1
Unrealized Gains and Losses on Derivative Instruments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	6	(43)	(84)
Other comprehensive income/(loss) before reclassifications	(40)	55	14
Amounts reclassified from AOCI	10	(6)	27
Net current period Other comprehensive income/(loss)	(30)	49	41
Ending balance	(24)	6	(43)
Defined Benefit Pension Plans & Other Postretirement Benefits
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(11,561)	(17,061)	(15,942)
Other comprehensive income/(loss) before reclassifications	1,529	4,268	(1,929)
Amounts reclassified from AOCI	673	1,232	810
Net current period Other comprehensive income/(loss)	2,202	5,500	(1,119)
Ending balance	(9,359)	(11,561)	(17,061)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(11,659)	(17,133)	(16,153)
Ending balance	$ (9,550)	$ (11,659)	$ (17,133)