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Allowance for Loan Losses - Loan Type (Detail) - FFELP Loans [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans, gross	$ 47,124	$ 54,619
Change	(7,495)
Stafford Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans, gross	14,956	16,719
Change	(1,763)
Consolidation Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans, gross	27,766	33,143
Change	(5,377)
Rehab Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans, gross	4,402	$ 4,757
Change	$ (355)

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- Definition

Financing receivable before allowance for credit loss and fee change amount

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- Definition

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

+ References

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