Accumulated Other Comprehensive Income - Activity in AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	$ 1,131	$ (2,992)
Other comprehensive income (loss), tax effect	(266)	689
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	17,327
Other comprehensive income (loss), net of tax	865	(2,303)
Ending balance	18,364
AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(5,110)	1,207
Other comprehensive income (loss), net of tax	865	(2,303)
Ending balance	(4,245)	(1,096)
Available-for-sale debt securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	788	(2,505)
Other comprehensive income (loss), before reclassifications, tax effect	(188)	576
Other comprehensive income (loss), before reclassifications, net activity	600	(1,929)
Reclassification adjustment, pre-tax activity	0	(3)
Reclassification adjustment, tax effect	0	1
Reclassification adjustment, net activity	0	(2)
Other comprehensive income (loss), pre-tax activity	788	(2,508)
Other comprehensive income (loss), tax effect	(188)	577
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4,589)	891
Other comprehensive income (loss), net of tax	600	(1,931)
Ending balance	(3,989)	(1,040)
Cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	278	(407)
Other comprehensive income (loss), before reclassifications, tax effect	(63)	94
Other comprehensive income (loss), before reclassifications, net activity	215	(313)
Reclassification adjustment, pre-tax activity	65	(78)
Reclassification adjustment, tax effect	(15)	18
Reclassification adjustment, net activity	50	(60)
Other comprehensive income (loss), pre-tax activity	343	(485)
Other comprehensive income (loss), tax effect	(78)	112
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(498)	353
Other comprehensive income (loss), net of tax	265	(373)
Ending balance	(233)	(20)
Defined benefit pension plants, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment, pre-tax activity	0	1
Reclassification adjustment, tax effect	0	0
Reclassification adjustment, net activity	0	1
Other comprehensive income (loss), pre-tax activity	0	1
Other comprehensive income (loss), tax effect	0	0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(19)	(33)
Other comprehensive income (loss), net of tax	0	1
Ending balance	(19)	(32)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	0	0
Other comprehensive income (loss), tax effect	0	0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4)	(4)
Other comprehensive income (loss), net of tax	0	0
Ending balance	$ (4)	$ (4)