XML 115 R100.htm IDEA: XBRL DOCUMENT
v3.19.1

Deposits - Narrative (Details) bank in Thousands | Dec. 31, 2018 USD ($) bank | Dec. 31, 2017 USD ($)
--- | --- | ---
Deposits [Line Items] |  |
Certificates of deposit | $ 113,273,000 |
CD collateralized by FHLB letters of credit | 0 | $ 0
Securities pledged to collateralize certificates of deposit | 0 | 0
Deposits held for related parties | $ 2,700,000 | 2,500,000
CDARS |  |
Deposits [Line Items] |  |
Number of banks in, more than | bank | 3 |
Percentage of coverage of certificates of deposit in CDARS | 100.00% |
Certificates of deposit | $ 0 | $ 0

X
- Definition Certificates of Deposits, Collateralized by Federal Home Loan Bank Letters of Credit + References No definition available. + Details
Name: | nrim_CertificatesofDepositsCollateralizedbyFederalHomeLoanBankLettersofCredit
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition [Line Items] for Deposits [Table] + References No definition available. + Details
Name: | nrim_DepositsLineItems
Namespace Prefix: | nrim_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of banks in Certificate Of Deposit Account Registry System. + References No definition available. + Details
Name: | nrim_NumberOfBanksInCertificateOfDepositAccountRegistrySystem
Namespace Prefix: | nrim_
Data Type: | xbrli:positiveIntegerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of coverage of certificates of deposit in Certificate Of Deposit Account Registry System. + References No definition available. + Details
Name: | nrim_PercentageOfCoverageOfCertificatesOfDepositInCertificateOfDepositAccountRegistrySystem
Namespace Prefix: | nrim_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of securities, mortgage loans, or other financial instruments pledged as collateral for deposits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818 + Details
Name: | us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of interest-bearing domestic certificate of deposit liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.12) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_InterestBearingDomesticDepositCertificatesOfDeposits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of deposits held by the entity for a related party (entity, shareholder, employee). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_RelatedPartyDepositLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=nrim_CertificateOfDepositAccountRegistrySystemMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |