Accumulated Other Comprehensive Income (Loss) - (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	$ 17,026	$ 16,991
Balance at end of period, common equity	15,775	17,026	$ 16,991
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	679	(279)	(366)
Balance at end of period, common equity	(179)	679	(279)
Accumulated other comprehensive income (loss) | Cumulative Effect, Period of Adoption, Adjusted Balance
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	679	(277)	(366)
Balance at end of period, common equity		679	(277)
Unrealized gains (losses) on investment securities:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	750	(116)	(519)
Net unrealized gains (losses) arising during the period, net of tax	(774)	944	459
Reclassification adjustment for (gains) losses realized in net income (loss)	(55)	(104)	(67)
Reversal of provision for credit losses realized in net income (loss), net of tax	0	(2)	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	14	26	11
Total other comprehensive income (loss) for period	(815)	864	403
Balance at end of period, common equity	(65)	750	(116)
Unrealized gains (losses) on investment securities: | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity		2
Balance at end of period, common equity			2
Unrealized gains (losses) on investment securities: | Cumulative Effect, Period of Adoption, Adjusted Balance
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	750	(114)	(519)
Balance at end of period, common equity		750	(114)
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	15	(9)	301
Net unrealized gains (losses) arising during the period, net of tax	12	24	(217)
Reclassification adjustment for (gains) losses realized in net income (loss)	0	0	(93)
Total other comprehensive income (loss) for period	12	24	(310)
Balance at end of period, common equity	27	15	(9)
Unrealized gains (losses) on derivatives designated as cash flow hedges:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(79)	(151)	(159)
Net unrealized gains (losses) arising during the period, net of tax	(49)	64	(19)
Reclassification adjustment for (gains) losses realized in net income (loss)	(10)	8	27
Total other comprehensive income (loss) for period	(59)	72	8
Balance at end of period, common equity	(138)	(79)	(151)
Pension and postretirement benefit liability:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period, common equity	(7)	(3)	11
Net unrealized gains (losses) arising during the period, net of tax	4	(4)	(14)
Total other comprehensive income (loss) for period	4	(4)	(14)
Balance at end of period, common equity	$ (3)	$ (7)	$ (3)