Shareholders' Equity (Accumulated other comprehensive income) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (11,659)	$ (17,133)
OCI before reclassifications	[1]	118	(23)
Amounts reclassified from AOCI	[1]	171	204
Net current period Other comprehensive income/(loss)	[1]	289	181
Ending Balance	[1]	(11,370)	(16,952)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax		159	228
Amortization of actuarial losses included in net periodic pension cost, tax		(40)	(65)
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 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(105)	(30)
OCI before reclassifications		24	(36)
Net current period Other comprehensive income/(loss)		24	(36)
Ending Balance		(81)	(66)
Unrealized Gains and Losses on Certain Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		1	1
Ending Balance		1	1
Unrealized Gains and Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		6	(43)
OCI before reclassifications		94	11
Amounts reclassified from AOCI		35	(2)
Net current period Other comprehensive income/(loss)		129	9
Ending Balance		135	(34)
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(11,561)	(17,061)
OCI before reclassifications			2
Amounts reclassified from AOCI		136	206
Net current period Other comprehensive income/(loss)		136	208
Ending Balance		$ (11,425)	$ (16,853)

[1] Net of tax.