Accumulated Other Comprehensive Loss (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]
Balance at beginning of period, common equity			$ 11,848
Total other comprehensive income (loss)	$ (176)	$ (585)	189	$ (1,751)
Balance at end of period, common equity	11,392	14,272	11,392	14,272
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(2,210)	(1,345)	(2,575)	(179)
Total other comprehensive income (loss)	(176)	(585)	189	(1,751)
Balance at end of period, common equity	(2,386)	(1,930)	(2,386)	(1,930)
Unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(2,066)	(1,108)	(2,270)	(65)
Net unrealized gains (losses) arising during the period, net of tax	(64)	(573)	143	(1,602)
Reclassification adjustment for (gains) losses realized in net income (loss), net of tax	0	(7)	(2)	(22)
Reversal of provision for credit losses realized in net income, net of tax	0	2	0	1
Amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity realized in net income (loss), net of tax	1	4	0	6
Total other comprehensive income (loss)	(63)	(574)	141	(1,617)
Balance at end of period, common equity	(2,129)	(1,682)	(2,129)	(1,682)
Tax on net unrealized gains (losses) arising during period	(21)	(182)	47	(509)
Tax on reclassification adjustment (less than)	0	(2)	(1)	(7)
Tax on reversal of provision for credit losses realized in net income (loss)	0	1	0	1
Tax on amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity realized in net income (loss)	1	1	0	2
Unrealized gains (losses) on fair value option liabilities attributable to our own credit spread
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	149	56	86	27
Net unrealized gains (losses) arising during the period, net of tax	(64)	51	(1)	80
Total other comprehensive income (loss)	(64)	51	(1)	80
Balance at end of period, common equity	85	107	85	107
Tax on net unrealized gains (losses) arising during period	(22)	16	(1)	25
Unrealized gains (losses) on derivatives designated as cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(298)	(290)	(396)	(138)
Net unrealized gains (losses) arising during the period, net of tax	(91)	(63)	(27)	(216)
Reclassification adjustment for (gains) losses realized in net income (loss), net of tax	42	1	76	2
Total other comprehensive income (loss)	(49)	(62)	49	(214)
Balance at end of period, common equity	(347)	(352)	(347)	(352)
Tax on net unrealized gains (losses) arising during period	(29)	(19)	(8)	(67)
Tax on reclassification adjustment (less than)	13	1	24	1
Pension and postretirement benefit liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	5	(3)	5	(3)
Balance at end of period, common equity	$ 5	$ (3)	$ 5	$ (3)