XML 142 R88.htm IDEA: XBRL DOCUMENT v2.4.1.9
Allowance For Loan Losses - Allowance For Loan Losses (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period $ 16,282us-gaap_FinancingReceivableAllowanceForCreditLosses $ 16,408us-gaap_FinancingReceivableAllowanceForCreditLosses
Charge-Offs (625)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs (1,196)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Recoveries 1,702us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery 1,705us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Provision (benefit) 636us-gaap_ProvisionForLoanLeaseAndOtherLosses 635us-gaap_ProvisionForLoanLeaseAndOtherLosses
Balance, end of period 16,723us-gaap_FinancingReceivableAllowanceForCreditLosses 16,282us-gaap_FinancingReceivableAllowanceForCreditLosses
Duration of loss history used to calculate general reserve 5 years  
Balance, end of period: Individually evaluated for impairment 75us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 11us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Balance, end of period: Collectively evaluated for impairment 16,648us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment 16,271us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Commercial    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 5,779us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
6,308us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Charge-Offs (319)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
(1,018)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Recoveries 1,041us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
1,049us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Provision (benefit) 858us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
560us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Balance, end of period 5,643us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
5,779us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 75us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 5,568us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
5,779us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialPortfolioSegmentMember
Real Estate Construction One-To- Four Family    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 557us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
1,029us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Charge-Offs 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Recoveries 625us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
77us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Provision (benefit) 538us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
549us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Balance, end of period 644us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
557us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 644us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
557us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOneToFourFamilyPortfolioSegmentMember
Real Estate Construction Other    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 539us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
326us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Charge-Offs 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
79us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Provision (benefit) (1,114)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
(134)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Balance, end of period 1,653us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
539us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 1,653us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
539us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateConstructionOtherPortfolioSegmentMember
Real Estate Term Owner Occupied    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 1,583us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
1,441us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Charge-Offs (160)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Provision (benefit) (157)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
(142)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Balance, end of period 1,580us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
1,583us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 1,580us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
1,583us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOwnerOccupiedPortfolioSegmentMember
Real Estate Term Non-Owner Occupied    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 4,297us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
4,065us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Charge-Offs 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
488us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Provision (benefit) (407)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
256us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Balance, end of period 4,704us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
4,297us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 4,704us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
4,297us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermNonOwnerOccupiedPortfolioSegmentMember
Real Estate Term Other    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 537us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
539us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Charge-Offs 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Provision (benefit) (119)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
2us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Balance, end of period 656us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
537us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 656us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
537us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_RealEstateTermOtherPortfolioSegmentMember
Consumer Secured By 1st Deed Of Trust    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 322us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
344us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Charge-Offs (59)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
(14)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Recoveries 4us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Provision (benefit) (18)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
8us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Balance, end of period 285us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
322us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
11us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 285us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
311us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerSecuredByFirstDeedOfTrustPortfolioSegmentMember
Consumer Other    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 390us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
388us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Charge-Offs (87)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
(164)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Recoveries 32us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
12us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Provision (benefit) (75)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
(154)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Balance, end of period 410us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
390us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Balance, end of period: Collectively evaluated for impairment 410us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
390us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= nrim_ConsumerOtherPortfolioSegmentMember
Unallocated    
Financing Receivable, Allowance for Credit Losses [Roll Forward]    
Balance, beginning of period 2,278us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
1,968us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
Charge-Offs 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
Provision (benefit) 1,130us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
(310)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
Balance, end of period 1,148us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
2,278us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
Balance, end of period: Individually evaluated for impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
Balance, end of period: Collectively evaluated for impairment $ 1,148us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember
$ 2,278us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember