Loans In Repayment And Percentage Of Each Status [Abstract]

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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- Definition

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

+ References

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- Definition

Percentage of financing receivable balance that is past due.

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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.

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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.

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Allowance for Loan Losses - Education Loans - Age Analysis of Past Due Loans Delinquencies (Detail) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2024
Loans in repayment and percentage of each status:
Loan allowance for losses	$ (464)	$ (592)	$ (537)	$ (426)	$ (530)	$ (621)
Private Education Loans [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	12,979	15,862
Loan allowance for losses	(299)	(406)	(364)	(263)	(348)	(441)
Loans, net	12,680	15,456
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	12,979	15,862	15,815
Loan allowance for losses	(299)	(406)	(364)
Loans, net	$ 12,680	$ 15,456	$ 15,451
Dimensions of concentration risk	100.00%	100.00%	100.00%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Current [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	94.90%	93.90%	93.70%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, 31 to 60 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Loans delinquent, percentage	1.90%	2.10%	2.10%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, 61 to 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Loans delinquent, percentage	1.00%	1.20%	1.30%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Loans delinquent, percentage	2.20%	2.80%	2.90%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Loans In Repayment [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	96.50%	96.00%	96.00%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Delinquent Loans in Repayment [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	5.10%	6.10%	6.30%
Private Education Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Forbearance, Loans In Repayment [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	1.90%	1.50%	1.50%
Private Education Loans [Member] \| School/Grace/Deferment [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	$ 216	$ 402	$ 395
Private Education Loans [Member] \| Forbearance [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	244	239	236
Private Education Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	12,519	15,221	15,184
Private Education Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financing Asset, Not Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	11,881	14,291	14,230
Private Education Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financial Asset, 31 to 60 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	233	315	326
Private Education Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financial Asset, 61 to 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	131	182	194
Private Education Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financial Asset, 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	274	433	434
FFELP Loans [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	26,063	29,138
Loan allowance for losses	(165)	(186)	(173)	$ (163)	$ (182)	$ (180)
Loans, net	25,898		28,141
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	26,063	29,138	28,314
Loan allowance for losses	(165)	(186)	(173)
Loans, net	$ 25,898	$ 28,952	$ 28,141
Dimensions of concentration risk	100.00%	100.00%	100.00%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Current [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	84.60%	81.90%	82.40%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, 31 to 60 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Loans delinquent, percentage	4.60%	4.40%	4.60%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, 61 to 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Loans delinquent, percentage	2.80%	3.20%	3.00%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Loans delinquent, percentage	8.00%	10.50%	10.00%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Loans In Repayment [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	83.90%	82.80%	83.30%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Delinquent Loans in Repayment [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	15.50%	18.10%	17.50%
FFELP Loans [Member] \| Credit Concentration Risk [Member] \| Financing Receivables, Forbearance, Loans In Repayment [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	12.40%	13.40%	13.00%
FFELP Loans [Member] \| School/Grace/Deferment [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	$ 1,097	$ 1,276	$ 1,210
FFELP Loans [Member] \| Forbearance [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	3,094	3,726	3,532
FFELP Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	21,872	24,136	23,572
FFELP Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financing Asset, Not Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	18,485	19,766	19,441
FFELP Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financial Asset, 31 to 60 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	1,015	1,062	1,075
FFELP Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financial Asset, 61 to 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	623	769	706
FFELP Loans [Member] \| Repayment [Member] \| Credit Concentration Risk [Member] \| Financial Asset, 90 Days Past Due [Member] \| Accounts Receivable [Member]
Loans in repayment and percentage of each status:
Total Loans, gross	$ 1,749	$ 2,539	$ 2,350