Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (8,796)	$ (9,913)	$ (8,977)
Other Comprehensive Income (Loss), Net of Tax	181	942
Derivative instruments	332	110
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(37)	55	59	$ 104
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(121)	(54)
Other Comprehensive Income (Loss), Tax	24	11
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(97)	(43)
Other Comprehensive Income (Loss), Net of Tax	(96)	(49)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	1	(8)
Reclassification from AOCI, Current Period, Tax	0	2
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1	(6)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(1,519)	(1,183)	(1,355)	(930)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(165)	(217)
Other Comprehensive Income (Loss), Tax	13	(36)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(152)	(253)
Other Comprehensive Income (Loss), Net of Tax	(164)	(253)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(12)	0
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(7,225)	(8,425)	(7,334)	(9,559)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	2	1,268
Other Comprehensive Income (Loss), Tax	0	(298)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	2	970
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	157	198
Reclassification from AOCI, Current Period, Tax	(50)	(34)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	107	164
Other Comprehensive Income (Loss), Net of Tax	109	1,134
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(15)	(360)	$ (347)	$ (470)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	420	122
Other Comprehensive Income (Loss), Tax	(56)	(9)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	364	113
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(34)	(3)
Reclassification from AOCI, Current Period, Tax	2	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(32)	(3)
Derivative instruments	$ 332	$ 110