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Goodwill and Intangible Assets - Narrative (Details) (USD $)
In Thousands, unless otherwise specified
0 Months Ended
Apr. 01, 2014
Dec. 02, 2014
Mar. 31, 2015
Dec. 31, 2014
Apr. 02, 2014
Finite-Lived Intangible Assets [Line Items]          
Goodwill     $ 22,334us-gaap_Goodwill $ 22,334us-gaap_Goodwill  
Alaska Pacific Bank          
Finite-Lived Intangible Assets [Line Items]          
Voting interests acquired         100.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
/ us-gaap_BusinessAcquisitionAxis
= nrim_AlaskaPacificBankMember
Alaska Pacific Bank | Core Deposits          
Finite-Lived Intangible Assets [Line Items]          
Intangible Assets Acquired 623us-gaap_FinitelivedIntangibleAssetsAcquired1
/ us-gaap_BusinessAcquisitionAxis
= nrim_AlaskaPacificBankMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CoreDepositsMember
       
Useful Life of Intangible Assets 10 years        
Residential Mortgage Holding Company          
Finite-Lived Intangible Assets [Line Items]          
Voting interests acquired   76.50%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
/ us-gaap_BusinessAcquisitionAxis
= nrim_ResidentialMortgageHoldingCompanyLlcMember
     
Goodwill   14,810us-gaap_Goodwill
/ us-gaap_BusinessAcquisitionAxis
= nrim_ResidentialMortgageHoldingCompanyLlcMember
     
Trade Names | Residential Mortgage Holding Company          
Finite-Lived Intangible Assets [Line Items]          
Indefinite-lived Intangible Assets Acquired   $ 950us-gaap_IndefinitelivedIntangibleAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= nrim_ResidentialMortgageHoldingCompanyLlcMember
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeNamesMember