Accumulated Other Comprehensive Income (Loss) - (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity			$ 15,775,000,000
Total other comprehensive income (loss)	$ (585,000,000)	$ 55,000,000	(1,751,000,000)	$ (598,000,000)
Balance at end of period, common equity	14,272,000,000	16,919,000,000	14,272,000,000	16,919,000,000
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(1,345,000,000)	26,000,000	(179,000,000)	679,000,000
Total other comprehensive income (loss)	(585,000,000)	55,000,000	(1,751,000,000)	(598,000,000)
Balance at end of period, common equity	(1,930,000,000)	81,000,000	(1,930,000,000)	81,000,000
Unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(1,108,000,000)	119,000,000	(65,000,000)	750,000,000
Net unrealized gains (losses) arising during the period, net of tax	(573,000,000)	63,000,000	(1,602,000,000)	(550,000,000)
Reclassification adjustment for (gains) losses realized in net income (loss), net of tax	(7,000,000)	(14,000,000)	(22,000,000)	(36,000,000)
Reversal of provision for credit losses realized in net income (loss), net of tax	2,000,000	0	1,000,000	0
Amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity realized in net income (loss), net of tax	4,000,000	4,000,000	6,000,000	8,000,000
Total other comprehensive income (loss)	(574,000,000)	53,000,000	(1,617,000,000)	(578,000,000)
Balance at end of period, common equity	(1,682,000,000)	172,000,000	(1,682,000,000)	172,000,000
Tax on net unrealized gains (losses) arising during period	(182,000,000)	21,000,000	(509,000,000)	(174,000,000)
Tax on reclassification adjustment	(2,000,000)	(4,000,000)	(7,000,000)	(11,000,000)
Tax on reversal of provision for credit losses realized in net income (loss)	1,000,000	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	1,000,000	2,000,000	2,000,000
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	56,000,000	5,000,000	27,000,000	15,000,000
Net unrealized gains (losses) arising during the period, net of tax	51,000,000	10,000,000	80,000,000	0
Total other comprehensive income (loss)	51,000,000	10,000,000	80,000,000	0
Balance at end of period, common equity	107,000,000	15,000,000	107,000,000	15,000,000
Tax on net unrealized gains (losses) arising during period	16,000,000	3,000,000	25,000,000	0
Unrealized gains (losses) on derivatives designated as cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(290,000,000)	(91,000,000)	(138,000,000)	(79,000,000)
Net unrealized gains (losses) arising during the period, net of tax	(63,000,000)	(6,000,000)	(216,000,000)	(19,000,000)
Reclassification adjustment for (gains) losses realized in net income (loss), net of tax	1,000,000	(3,000,000)	2,000,000	(2,000,000)
Total other comprehensive income (loss)	(62,000,000)	(9,000,000)	(214,000,000)	(21,000,000)
Balance at end of period, common equity	(352,000,000)	(100,000,000)	(352,000,000)	(100,000,000)
Tax on net unrealized gains (losses) arising during period	(19,000,000)	(2,000,000)	(67,000,000)	(6,000,000)
Tax on reclassification adjustment	1,000,000	(1,000,000)	1,000,000	(1,000,000)
Pension and postretirement benefit liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(3,000,000)	(7,000,000)	(3,000,000)	(7,000,000)
Net unrealized gains (losses) arising during the period, net of tax	0	1,000,000	0	1,000,000
Total other comprehensive income (loss)	0	1,000,000	0	1,000,000
Balance at end of period, common equity	(3,000,000)	(6,000,000)	(3,000,000)	(6,000,000)
Tax on net unrealized gains (losses) arising during period	$ 0	$ 1,000,000	$ 0	$ 1,000,000