XML 48 R36.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Allowance for Loan Losses - Recorded Investment, Unpaid Principal Balance and Related Allowance for TDR Loans (Detail) - USD ($) $ in Millions | Jun. 30, 2016 | Dec. 31, 2015
--- | --- | ---
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
TDR Loans, Recorded Investment | $ 10,760 | $ 10,575
TDR loans, Unpaid Principal Balance | 10,819 | 10,642
TDR Loans, Related Allowance | 1,163 | 1,209
Private Education Loans - Traditional [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
TDR Loans, Recorded Investment | 9,351 | 9,134
TDR loans, Unpaid Principal Balance | 9,404 | 9,200
TDR Loans, Related Allowance | 964 | 995
Private Education Loans - Non-Traditional [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
TDR Loans, Recorded Investment | 1,409 | 1,441
TDR loans, Unpaid Principal Balance | 1,415 | 1,442
TDR Loans, Related Allowance | $ 199 | $ 214

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

X
- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Recorded Investment -URI http://asc.fasb.org/extlink&oid=65880944 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investment in impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=navi_PrivateEducationLoansTraditionalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=navi_PrivateEducationLoansNonTraditionalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |