XML 44 R33.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Investment Securities - Schedule of Amortized Cost and Fair Value by Contractual Maturity of Debt Securities (Details) - Municipal securities $ in Thousands | Sep. 30, 2017 USD ($)
--- | ---
Schedule Of Debt Securities [Line Items] |
Within 1 year, amortized cost | $ 3,904
1-5 years, amortized cost | 12,770
5-10 years, amortized cost | 1,489
Amortized Cost | 18,163
Within 1 year, fair value | 3,911
1-5 years, fair value | 12,873
5-10 years, fair value | 1,478
Fair Value | $ 18,262
Within 1 year, weighted average yield | 1.37%
1-5 years, weighted average yield | 2.26%
5-10 years, weighted average yield | 4.78%
Weighted Average Yield | 2.27%

X
- Definition Debt Securities After Five Through Ten Years Weighted Average Yield + References No definition available. + Details
Name: | nrim_DebtSecuritiesAfterFiveThroughTenYearsWeightedAverageYield
Namespace Prefix: | nrim_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Securities After One Through Five Years Weighted Average Yield + References No definition available. + Details
Name: | nrim_DebtSecuritiesAfterOneThroughFiveYearsWeightedAverageYield
Namespace Prefix: | nrim_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt securities amortized cost + References No definition available. + Details
Name: | nrim_DebtSecuritiesAmortizedCost
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt securities fair value + References No definition available. + Details
Name: | nrim_DebtSecuritiesFairValue
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities Maturities After Five Through Ten Years Amortized Cost + References No definition available. + Details
Name: | nrim_DebtSecuritiesMaturitiesAfterFiveThroughTenYearsAmortizedCost
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities Maturities After Five Through Ten Years Fair Value + References No definition available. + Details
Name: | nrim_DebtSecuritiesMaturitiesAfterFiveThroughTenYearsFairValue
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities Maturities After One Through Five Years Amortized Cost + References No definition available. + Details
Name: | nrim_DebtSecuritiesMaturitiesAfterOneThroughFiveYearsAmortizedCost
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities Maturities After One Through Five Years Fair Value + References No definition available. + Details
Name: | nrim_DebtSecuritiesMaturitiesAfterOneThroughFiveYearsFairValue
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities Maturities Within One Year Amortized Cost + References No definition available. + Details
Name: | nrim_DebtSecuritiesMaturitiesWithinOneYearAmortizedCost
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt securities maturities within one year fair value + References No definition available. + Details
Name: | nrim_DebtSecuritiesMaturitiesWithinOneYearFairValue
Namespace Prefix: | nrim_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities Weighted Average Yield. + References No definition available. + Details
Name: | nrim_DebtSecuritiesWeightedAverageYield
Namespace Prefix: | nrim_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Securities Within One Year Weighted Average Yield + References No definition available. + Details
Name: | nrim_DebtSecuritiesWithinOneYearWeightedAverageYield
Namespace Prefix: | nrim_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Schedule Of Debt Securities [Line Items] + References No definition available. + Details
Name: | nrim_ScheduleOfDebtSecuritiesLineItems
Namespace Prefix: | nrim_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |