Expense on cancellation of loans.

No definition available.

Name:	navi_ExpenseOnCancellationOfLoans
Namespace Prefix:	navi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Financing receivable, loans cancelled, aggregate outstanding.

+ References

No definition available.

+ Details

Name:	navi_FinancingReceivableLoansCancelledAggregateOutstanding
Namespace Prefix:	navi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of borrowers whose loans are cancelled.

+ References

No definition available.

+ Details

Name:	navi_NumberOfBorrowersWhoseLoansAreCancelled
Namespace Prefix:	navi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of State Attorneys General under agreement.

+ References

No definition available.

+ Details

Name:	navi_NumberOfStateAttorneysGeneralUnderAgreement
Namespace Prefix:	navi_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

One-time payment payable.

+ References

No definition available.

+ Details

Name:	navi_OneTimePaymentPayable
Namespace Prefix:	navi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Aggregate carrying amount of the estimated litigation liability for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementExpense
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

No definition available.

+ Details

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

- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

+ Details

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

- Details

Name:	dei_LegalEntityAxis=navi_SLMBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended
	Jan. 31, 2022 USD ($) StateAttorneysGeneral Borrower	Dec. 31, 2021 USD ($)	Mar. 31, 2016 Case	Sep. 30, 2022 USD ($)
Loss Contingencies [Line Items]
Number of cases filed \| Case			3
Number of State Attorneys General under Agreement \| StateAttorneysGeneral	40
Number of borrowers involved in cancellation of loan balance \| Borrower	66,000
Aggregate outstanding balance of loans cancelled	$ 1,700,000,000
Expense on cancellation of loans	50,000,000
One-time payment	$ 145,000,000
Regulatory expenses		$ 205,000,000
SLM BankCo [Member] \| Indemnification Matters [Member]
Loss Contingencies [Line Items]
Reserve for estimated amounts and costs incurred				$ 0