Accumulated Other Comprehensive Loss (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	$ 11,848,000,000	$ 15,775,000,000
Total other comprehensive income (loss)	649,000,000	(2,396,000,000)	$ (858,000,000)
Balance at end of period, common equity	11,374,000,000	11,848,000,000	15,775,000,000
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(2,575,000,000)	(179,000,000)	679,000,000
Total other comprehensive income (loss)	649,000,000	(2,396,000,000)	(858,000,000)
Balance at end of period, common equity	(1,926,000,000)	(2,575,000,000)	(179,000,000)
Unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(2,270,000,000)	(65,000,000)	750,000,000
Net unrealized gains (losses) arising during the period, net of tax	353,000,000	(2,192,000,000)	(774,000,000)
Reclassification adjustment for (gains) losses realized in net income (loss), net of tax	185,000,000	(20,000,000)	(55,000,000)
Reversal of provision for credit losses realized in net income, net of tax	0	(1,000,000)	0
Amortization of net unrealized (gains) losses on securities transferred from available-for-sale to held-to-maturity realized in net income, net of tax	(2,000,000)	8,000,000	14,000,000
Total other comprehensive income (loss)	536,000,000	(2,205,000,000)	(815,000,000)
Balance at end of period, common equity	(1,734,000,000)	(2,270,000,000)	(65,000,000)
Tax on net unrealized gains (losses) arising during period	109,000,000	(716,000,000)	(244,000,000)
Tax on reclassification adjustment (less than)	58,000,000	(6,000,000)	(18,000,000)
Tax on reversal of provision for credit losses realized in net income (loss)	0	(1,000,000)	0
Tax on amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity realized in net income (loss)	(1,000,000)	3,000,000	4,000,000
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	86,000,000	27,000,000	15,000,000
Net unrealized gains (losses) arising during the period, net of tax	(25,000,000)	59,000,000	12,000,000
Total other comprehensive income (loss)	(25,000,000)	59,000,000	12,000,000
Balance at end of period, common equity	61,000,000	86,000,000	27,000,000
Tax on net unrealized gains (losses) arising during period	(8,000,000)	19,000,000	4,000,000
Unrealized gains (losses) on derivatives designated as cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(396,000,000)	(138,000,000)	(79,000,000)
Net unrealized gains (losses) arising during the period, net of tax	4,000,000	(291,000,000)	(49,000,000)
Reclassification adjustment for (gains) losses realized in net income (loss), net of tax	132,000,000	33,000,000	(10,000,000)
Total other comprehensive income (loss)	136,000,000	(258,000,000)	(59,000,000)
Balance at end of period, common equity	(260,000,000)	(396,000,000)	(138,000,000)
Tax on net unrealized gains (losses) arising during period	1,000,000	(94,000,000)	(16,000,000)
Tax on reclassification adjustment (less than)	42,000,000	10,000,000	(3,000,000)
Pension and postretirement benefit liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	5,000,000	(3,000,000)	(7,000,000)
Net unrealized gains (losses) arising during the period, net of tax	2,000,000	8,000,000	4,000,000
Total other comprehensive income (loss)	2,000,000	8,000,000	4,000,000
Balance at end of period, common equity	7,000,000	5,000,000	(3,000,000)
Tax on net unrealized gains (losses) arising during period	$ 1,000,000	$ 2,000,000	$ 1,000,000