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v3.19.3.a.u2

Commitments, Contingencies and Guarantees (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) attorney_general
Loss Contingencies [Line Items] |
Contractual obligation | $ 1,900
Other liabilities reserve | $ 2
Loss emergence period | 1 year
California, Washington And Pennsylvania |
Loss Contingencies [Line Items] |
Number of state attorneys general | attorney_general | 3

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- Definition Loss Contingency, Loss Emergence Period + References No definition available. + Details
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Namespace Prefix: | slm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of Attorneys General + References No definition available. + Details
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Namespace Prefix: | slm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Other Liabilities Reserve + References No definition available. + Details
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Namespace Prefix: | slm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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. + Details
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Namespace Prefix: | us-gaap_
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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |