Education Loans - Education Loan Portfolio by Program (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 62,250	$ 72,812
Percentage to total education loans	100.00%	100.00%
Average Balance education loans	$ 69,707	$ 77,243
Average Effective Interest Rate of education loans	4.53%	3.42%
FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 43,525	$ 52,641
Stafford Loans [Member] \| FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 15,691	$ 18,219
Percentage to total education loans	25.00%	25.00%
Average Balance education loans	$ 17,475	$ 19,270
Average Effective Interest Rate of education loans	3.93%	2.19%
Consolidation Loans [Member] \| FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 27,834	$ 34,422
Percentage to total education loans	45.00%	47.00%
Average Balance education loans	$ 31,708	$ 36,748
Average Effective Interest Rate of education loans	4.04%	2.84%
Private Education Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 18,725	$ 20,171
Percentage to total education loans	30.00%	28.00%
Average Balance education loans	$ 20,524	$ 21,225
Average Effective Interest Rate of education loans	5.82%	5.57%

Represents the average balance of outstanding student loans during the period presented.

No definition available.

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- Definition

Percentage to total student loans.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Amortized cost, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Yield on the receivable, on which interest has been imputed, as calculated from its issuance value or purchase price. The calculated effective interest rate considers factors such as the issued face value or price paid for the receivable, the time period between payments, and the time until maturity [full receipt] of the receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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