Debt Instrument, Loans Transferred

No definition available.

Name:	slm_DebtInstrumentLoansTransferred
Namespace Prefix:	slm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Weighted Average Life

+ References

No definition available.

+ Details

Name:	slm_DebtInstrumentWeightedAverageLife
Namespace Prefix:	slm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482949/835-30-55-8

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69B

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69C

Reference 5: 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

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-5

+ Details

Name:	us-gaap_DerivativeBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-20

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=slm_SMBPrivateEducationLoanTrust2025AMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=slm_SMBPrivateEducationLoanTrust2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=slm_SMBPrivateEducationLoanTrust2026AMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=slm_SMBPrivateEducationLoanTrust2026Member
Namespace Prefix:
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Balance Type:
Period Type:

Borrowings - Secured Financing (Details) - USD ($) $ in Thousands			1 Months Ended		6 Months Ended
	Mar. 11, 2026	May 07, 2025	Mar. 31, 2026	May 31, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Securities Financing Transaction [Line Items]
Loans Transferred to the Trust					$ 632,214		$ 513,140
2025-A ABS Transaction
Securities Financing Transaction [Line Items]
Loans Transferred to the Trust		$ 576,908
Notes Issued		539,000
Gross Proceeds		$ 538,889
Weighted Average Cost of Funds (as a percent)		1.49%
Weighted Average Life of Notes (in years)				5 years 5 months 15 days
SMB Private Education Loan Trust 2025
Securities Financing Transaction [Line Items]
Loans Transferred to the Trust							576,908
Notes Issued							$ 539,000
Gross Proceeds						$ 538,889
2026-A ABS Transaction
Securities Financing Transaction [Line Items]
Loans Transferred to the Trust	$ 649,813
Notes Issued	618,000
Gross Proceeds	$ 617,781
Weighted Average Cost of Funds (as a percent)	1.15%
Weighted Average Life of Notes (in years)			5 years 7 months 20 days
SMB Private Education Loan Trust 2026
Securities Financing Transaction [Line Items]
Loans Transferred to the Trust					649,813
Notes Issued					618,000
Gross Proceeds					$ 617,781