Allowance for Loan Losses - Summary of Performance and Related Loan Status of Loans Modified (Parenthetical) (Details) $ in Millions	9 Months Ended
Sep. 30, 2023 USD ($)
Private Education Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans modified, charged off	$ 5

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Period Type:	duration