Education Loans - Education Loan Portfolio by Program (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 54,827	$ 62,250
Percentage to total education loans	100.00%	100.00%
Average Balance education loans	$ 59,654	$ 69,707
Average Effective Interest Rate of education loans	7.15%	4.53%
FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 37,925	$ 43,525
Stafford Loans [Member] \| FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 13,564	$ 15,691
Percentage to total education loans	25.00%	25.00%
Average Balance education loans	$ 14,949	$ 17,475
Average Effective Interest Rate of education loans	7.44%	3.93%
Consolidation Loans [Member] \| FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 24,361	$ 27,834
Percentage to total education loans	44.00%	45.00%
Average Balance education loans	$ 26,242	$ 31,708
Average Effective Interest Rate of education loans	6.80%	4.04%
Private Education Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Ending Balance of education loans	$ 16,902	$ 18,725
Percentage to total education loans	31.00%	30.00%
Average Balance education loans	$ 18,463	$ 20,524
Average Effective Interest Rate of education loans	7.42%	5.82%

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

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+ 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
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
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Reference 2: 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 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-5

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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://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482900/835-30-50-1

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