XML 54 R45.htm IDEA: XBRL DOCUMENT
v3.22.2

Loans - Narrative, Past Due and Non-Accrual Loans (Details) - USD ($) $ in Thousands | 6 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2022 | Sep. 30, 2021 | Dec. 31, 2021
Receivables [Abstract] |  |  |
Non-accrual loans | $ 10,263 |  | $ 7,622
Criteria days for delinquent status | 90 days | 90 days | 90 days
Principal balance of loans on non accrual status, less then | $ 500 |  |
Impairment of loans | 5,400 |  | $ 4,200
Loans on non accrual status with principal balances below threshold definition of an impaired loan | 4,900 |  | 3,400
90 days or more past due and accruing | $ 211 |  | $ 384

X
- Definition Delinquent status classification criteria days minimum. + References No definition available. + Details
Name: | nfbk_DelinquentStatusClassificationCriteriaDaysMinimum
Namespace Prefix: | nfbk_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Loans deemed to be impaired non accrual amount. + References No definition available. + Details
Name: | nfbk_LoansDeemedToBeImpairedNonAccrualAmount
Namespace Prefix: | nfbk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Loans on non accrual status with principal balances below threshold definition of an impaired loan + References No definition available. + Details
Name: | nfbk_LoansOnNonAccrualStatusWithPrincipalBalancesBelowThresholdDefinitionOfImpairedLoan
Namespace Prefix: | nfbk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Principal balance threshold for non accrual status. + References No definition available. + Details
Name: | nfbk_PrincipalBalanceThresholdForNonAccrualStatus
Namespace Prefix: | nfbk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable 90 days or more past due and still accruing. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable on nonaccrual status. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual
Namespace Prefix: | us-gaap_
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