XML 99 R81.htm IDEA: XBRL DOCUMENT
v3.20.4

Allowance for Credit Losses - Accrued Interest Receivable (Detail) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Receivables [Abstract] |  |
Total Interest Receivable | $ 1,168,895,000 | $ 1,366,158,000
Greater Than 90 Days Past Due | 4,354,000 | 2,390,000
Allowance for Uncollectible Interest | 4,467,000 | $ 5,309,000
Monthly payment that is smaller than the interest accrued on the loan in that month | $ 25 |

X
- Definition Accrued interest receivable on private education loans. + References No definition available. + Details
Name: | slm_AccruedInterestReceivableOnPrivateEducationLoans
Namespace Prefix: | slm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Allowance For Uncollectible Accrued Interest + References No definition available. + Details
Name: | slm_AllowanceForUncollectibleAccruedInterest
Namespace Prefix: | slm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fixed-Pay Loan, Monthly Payment Amount, Below Monthly Accrued Interest + References No definition available. + Details
Name: | slm_FixedPayLoanMonthlyPaymentAmountBelowMonthlyAccruedInterest
Namespace Prefix: | slm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Greater than ninety days past due accrued interest receivable. + References No definition available. + Details
Name: | slm_GreaterThanNinetyDaysPastDueAccruedInterestReceivable
Namespace Prefix: | slm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ReceivablesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration