Accumulated Other Comprehensive Income - Activity in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	$ (3,472)	$ (438)	$ (8,481)	$ (1,250)
Other comprehensive income (loss), tax effect	810	101	1,968	286
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	18,970	22,926	22,210	23,111
Other comprehensive loss, net of tax	(2,662)	(337)	(6,513)	(964)
Balance	16,736	22,524	16,736	22,524
Net actuarial loss arising during the year	(1)	(1)	(2)	(2)
AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(2,644)	1,974	1,207	2,601
Other comprehensive loss, net of tax	(2,662)	(337)	(6,513)	(964)
Balance	(5,306)	1,637	(5,306)	1,637
Available-for-sale debt securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(2,780)	(368)	(7,249)	(978)
Other comprehensive income (loss), before reclassifications, tax effect	651	87	1,685	230
Other comprehensive income (loss), before reclassifications, net activity	(2,129)	(281)	(5,564)	(748)
Reclassification adjustment, pre-tax activity	0	(1)	(3)	9
Reclassification adjustment, tax effect	0	0	1	(2)
Reclassification adjustment, net activity	0	(1)	(2)	7
Other comprehensive income (loss), pre-tax activity	(2,780)	(369)	(7,252)	(969)
Other comprehensive income (loss), tax effect	651	87	1,686	228
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(2,546)	1,472	891	1,931
Other comprehensive loss, net of tax	(2,129)	(282)	(5,566)	(741)
Balance	(4,675)	1,190	(4,675)	1,190
Cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(688)	3	(1,092)	(67)
Other comprehensive income (loss), before reclassifications, tax effect	158	(1)	252	14
Other comprehensive income (loss), before reclassifications, net activity	(530)	2	(840)	(53)
Reclassification adjustment, pre-tax activity	(4)	(74)	(140)	(219)
Reclassification adjustment, tax effect	1	16	31	46
Reclassification adjustment, net activity	(3)	(58)	(109)	(173)
Other comprehensive income (loss), pre-tax activity	(692)	(71)	(1,232)	(286)
Other comprehensive income (loss), tax effect	159	15	283	60
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(63)	548	353	718
Other comprehensive loss, net of tax	(533)	(56)	(949)	(226)
Balance	(596)	492	(596)	492
Defined benefit pension plants, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(1)	(1)	(2)	(2)
Other comprehensive income (loss), before reclassifications, tax effect	0	0	0	0
Other comprehensive income (loss), before reclassifications, net activity	(1)	(1)	(2)	(2)
Reclassification adjustment, pre-tax activity	1	3	5	7
Reclassification adjustment, tax effect	0	(1)	(1)	(2)
Reclassification adjustment, net activity	1	2	4	5
Other comprehensive income (loss), pre-tax activity	0	2	3	5
Other comprehensive income (loss), tax effect	0	(1)	(1)	(2)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(31)	(42)	(33)	(44)
Other comprehensive loss, net of tax	0	1	2	3
Balance	(31)	(41)	(31)	(41)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	0	0	0	0
Other comprehensive income (loss), tax effect	0	0	0	0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(4)	(4)	(4)	(4)
Other comprehensive loss, net of tax	0	0	0	0
Balance	$ (4)	$ (4)	$ (4)	$ (4)