Accumulated Other Comprehensive Income - Activity in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	$ (1,203)	$ (2,019)	$ (73)	$ (5,011)
Other comprehensive income (loss), tax effect	282	471	17	1,160
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			17,327
Other comprehensive loss, net of tax	(921)	(1,548)	(56)	(3,851)
Ending balance	17,809		17,809
AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4,245)	(1,096)	(5,110)	1,207
Other comprehensive loss, net of tax	(921)	(1,548)	(56)	(3,851)
Ending balance	(5,166)	(2,644)	(5,166)	(2,644)
Available-for-sale debt securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(831)	(1,964)	(43)	(4,469)
Other comprehensive income (loss), before reclassifications, tax effect	198	458	10	1,034
Other comprehensive income (loss), before reclassifications, net activity	(633)	(1,506)	(33)	(3,435)
Reclassification adjustment, pre-tax activity	0	0	0	(3)
Reclassification adjustment, tax effect	0	0	0	1
Reclassification adjustment, net activity	0	0	0	(2)
Other comprehensive income (loss), pre-tax activity	(831)	(1,964)	(43)	(4,472)
Other comprehensive income (loss), tax effect	198	458	10	1,035
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(3,989)	(1,040)	(4,589)	891
Other comprehensive loss, net of tax	(633)	(1,506)	(33)	(3,437)
Ending balance	(4,622)	(2,546)	(4,622)	(2,546)
Cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(454)	2	(177)	(405)
Other comprehensive income (loss), before reclassifications, tax effect	102	0	40	95
Other comprehensive income (loss), before reclassifications, net activity	(352)	2	(137)	(310)
Reclassification adjustment, pre-tax activity	81	(58)	146	(136)
Reclassification adjustment, tax effect	(18)	13	(33)	30
Reclassification adjustment, net activity	63	(45)	113	(106)
Other comprehensive income (loss), pre-tax activity	(373)	(56)	(31)	(541)
Other comprehensive income (loss), tax effect	84	13	7	125
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(233)	(20)	(498)	353
Other comprehensive loss, net of tax	(289)	(43)	(24)	(416)
Ending balance	(522)	(63)	(522)	(63)
Defined benefit pension plants, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	0	(1)	0	(1)
Other comprehensive income (loss), before reclassifications, tax effect	0	0	0	0
Other comprehensive income (loss), before reclassifications, net activity	0	(1)	0	(1)
Reclassification adjustment, pre-tax activity	1	2	1	3
Reclassification adjustment, tax effect	0	0	0	0
Reclassification adjustment, net activity	1	2	1	3
Other comprehensive income (loss), pre-tax activity	1	1	1	2
Other comprehensive income (loss), tax effect	0	0	0	0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(19)	(32)	(19)	(33)
Other comprehensive loss, net of tax	1	1	1	2
Ending balance	(18)	(31)	(18)	(31)
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]
Beginning balance	(4)	(4)	(4)	(4)
Other comprehensive loss, net of tax	0	0	0	0
Ending balance	$ (4)	$ (4)	$ (4)	$ (4)