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Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Parenthetical) (Detail) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Commercial [Member] | Commercial Real Estate Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Mortgage loans held for sale | $ 563 | $ 189
One-to-Four Family Residential [Member] | Residential [Member] | Residential Mortgage Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Mortgage loans held for sale | $ 165 | $ 190

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- Definition Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481990/310-10-45-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 948 -SubTopic 310 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481852/948-310-45-1 + Details
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