XML 50 R37.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Allowance for Loan Losses - Additional Information (Detail) | 6 Months Ended |  |
--- | --- | --- | ---
Jun. 30, 2016 | Dec. 31, 2015 | Jul. 01, 2006
Receivables [Abstract] |  |  |
Percentage of loans granted forbearance qualified as TDR | 24.00% | 23.00% |
Criteria for loans to be considered as nonperforming | 90 days |  |
Tier 1 of government guarantee (in percentage) | 97.00% |  | 97.00%
TDR payment default period | 60 days |  |
Period of loans past due that have accrued interest | 90 days |  |

X
- Definition Criteria for loans to be considered as nonperforming. + References No definition available. + Details
Name: | slm_CriteriaForLoansToBeConsideredAsNonperforming
Namespace Prefix: | slm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Loans and Leases Receivable, Impaired, Loans Granted Forbearance Qualified as Trouble Debt Restructuring + References No definition available. + Details
Name: | slm_LoansandLeasesReceivableImpairedLoansGrantedForbearanceQualifiedasTroubleDebtRestructuring
Namespace Prefix: | slm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Payment Default Period For Troubled Debt Restructurings + References No definition available. + Details
Name: | slm_PaymentDefaultPeriodForTroubledDebtRestructurings
Namespace Prefix: | slm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of Loans Past Due That Have Accrued Interest + References No definition available. + Details
Name: | slm_PeriodofLoansPastDueThatHaveAccruedInterest
Namespace Prefix: | slm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tier One of Government Guarantee + References No definition available. + Details
Name: | slm_TierOneofGovernmentGuarantee
Namespace Prefix: | slm_
Data Type: | num:percentItemType
Balance Type: | na
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