Accumulated Other Comprehensive Income - Activity in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	$ 823	$ (8,284)	$ (1,826)
Other comprehensive income (loss), tax effect	(200)	1,967	432
Other comprehensive income (loss), net of tax	623	(6,317)	(1,394)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	17,327	22,210	23,111
Other comprehensive (loss) income, net of tax	623	(6,317)	(1,394)
Ending balance	19,172	17,327	22,210
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), net of tax	623	(6,317)	(1,394)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,110)	1,207	2,601
Other comprehensive (loss) income, net of tax	623	(6,317)	(1,394)
Ending balance	(4,487)	(5,110)	1,207
Available-for-sale debt securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	656	(7,194)	(1,366)
Other comprehensive income (loss), before reclassifications, tax effect	(162)	1,716	323
Other comprehensive income (loss), before reclassifications, net activity	494	(5,478)	(1,043)
Reclassification adjustment, pre-tax activity	1	(2)	4
Reclassification adjustment, tax effect	0	0	(1)
Reclassification adjustment, net activity	1	(2)	3
Other comprehensive income (loss), pre-tax activity	657	(7,196)	(1,362)
Other comprehensive income (loss), tax effect	(162)	1,716	322
Other comprehensive income (loss), net of tax	495	(5,480)	(1,040)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,589)	891	1,931
Other comprehensive (loss) income, net of tax	495	(5,480)	(1,040)
Ending balance	(4,094)	(4,589)	891
Cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(171)	(1,006)	(185)
Other comprehensive income (loss), before reclassifications, tax effect	40	232	43
Other comprehensive income (loss), before reclassifications, net activity	(131)	(774)	(142)
Reclassification adjustment, pre-tax activity	334	(99)	(293)
Reclassification adjustment, tax effect	(77)	22	70
Reclassification adjustment, net activity	257	(77)	(223)
Other comprehensive income (loss), pre-tax activity	163	(1,105)	(478)
Other comprehensive income (loss), tax effect	(37)	254	113
Other comprehensive income (loss), net of tax	126	(851)	(365)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(498)	353	718
Other comprehensive (loss) income, net of tax	126	(851)	(365)
Ending balance	(372)	(498)	353
Defined benefit pension plans, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(1)	11	5
Other comprehensive income (loss), before reclassifications, tax effect	0	(2)	(1)
Other comprehensive income (loss), before reclassifications, net activity	(1)	9	4
Reclassification adjustment, pre-tax activity	4	6	9
Reclassification adjustment, tax effect	(1)	(1)	(2)
Reclassification adjustment, net activity	3	5	7
Other comprehensive income (loss), pre-tax activity	3	17	14
Other comprehensive income (loss), tax effect	(1)	(3)	(3)
Other comprehensive income (loss), net of tax	2	14	11
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(19)	(33)	(44)
Other comprehensive (loss) income, net of tax	2	14	11
Ending balance	(17)	(19)	(33)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	0	0	0
Other comprehensive income (loss), tax effect	0	0	0
Other comprehensive income (loss), net of tax	0	0	0
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4)	(4)	(4)
Other comprehensive (loss) income, net of tax	0	0	0
Ending balance	$ (4)	$ (4)	$ (4)