XML 58 R48.htm IDEA: XBRL DOCUMENT
v3.19.2

Borrowed Funds (Maturity and weighted average interest rates of FHLB advances) (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 2.27% | 2.20%
FHLB advances | $ 295,000 | $ 300,000
Fixed Rate Advances Due 2019 [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 1.89% | 1.94%
FHLB fixed rate advances | $ 50,000 | $ 100,000
Fixed Rate Advances Due 2020 [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 2.18% | 2.18%
FHLB fixed rate advances | $ 55,000 | $ 55,000
Fixed Rate Advances Due 2021 [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 1.91% | 1.91%
FHLB fixed rate advances | $ 50,000 | $ 50,000
Federal Home Loan Bank, Advances, Variable Rate Due 2021 [Member] [Member] [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
Federal Home Loan Bank, Advances, Floating Rate | $ 10,000 | $ 10,000
FHLB advances, rate | 2.82% | 2.93%
Federal Home Loan Bank, Advances, Fixed Rate Due 2022 [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 1.97% | 1.97%
FHLB fixed rate advances | $ 20,000 | $ 20,000
Fixed Rate Advances Due 2023 [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 2.97% | 3.17%
FHLB fixed rate advances | $ 45,000 | $ 35,000
Federal Home Loan Bank, Advances, Fixed Rate Due 2024 [Member] [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 2.68% | 2.96%
FHLB fixed rate advances | $ 55,000 | $ 20,000
Federal Home Loan Bank, Advances, Fixed Rate Due 2026 [Member] |  |
Federal Home Loan Bank, Advances [Line Items] |  |
FHLB advances, rate | 1.17% | 1.17%
FHLB fixed rate advances | $ 10,000 | $ 10,000

X
- Definition Par amount of advances made and reported by Federal Home Loan Bank (FHLBank) with fixed interest rate. + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesFixedRate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Par amount of advances made and reported by Federal Home Loan Bank (FHLBank) with floating interest rate. + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesFloatingRate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Interest rate of advances made and reported by Federal Home Loan Bank (FHLBank). + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Par amount of advances made and reported by Federal Home Loan Bank (FHLBank). + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesParValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesVariableRateDue2021MemberMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2024MemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=isba_FederalHomeLoanBankAdvancesFixedRateDue2026Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |