Loans and Allowance for Credit Losses - Summary Of Loans That Defaulted And Modified (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable Excluding Accrued Interest Modified In Period Amount	$ 1,123	$ 1,879
Payment Deferral And Extended Maturity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable Excluding Accrued Interest Modified In Period Amount	100	151
Contractual Interest Rate Reduction Extended Maturity And Payment Deferral [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable Excluding Accrued Interest Modified In Period Amount	1	6
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Payment Deferral And Extended Maturity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable Excluding Accrued Interest Modified In Period Amount	2	2
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Contractual Interest Rate Reduction Extended Maturity And Payment Deferral [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable Excluding Accrued Interest Modified In Period Amount	$ 1	$ 1