XML 60 R50.htm IDEA: XBRL DOCUMENT
v3.19.2

Borrowed Funds (Pledged financial instruments) (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Disclosure [Abstract] |  |
Pledged to secure borrowed funds | $ 427,819 | $ 431,430
Pledged to secure repurchase agreements | 25,477 | 40,316
Pledged for public deposits and for other purposes necessary or required by law | 34,177 | 58,107
Total | 487,473 | 529,853
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | 25,477 | 40,316
State and Local Funds Purchased [Member] |  |
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | 25,477 | 23,268
Mortgage Backed Securities, Other [Member] |  |
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | 0 | 10,736
Collateralized Mortgage Obligations [Member] |  |
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | $ 0 | $ 6,312

X
- Definition Pledged Financial Instruments, Available for Sale Securities, without Single Maturity Date + References No definition available. + Details
Name: | isba_PledgedFinancialInstrumentsAvailableforSaleSecuritieswithoutSingleMaturityDate
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Pledged Financial Instruments, Not Separately Reported, Securities And Loans Receivable, For Federal Home Loan Bank Debt And Federal Reserve Bank Discount Window + References No definition available. + Details
Name: | isba_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesAndLoansReceivableForFederalHomeLoanBankDebtAndFederalReserveBankDiscountWindow
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Pledged Financial Instruments, Not Separately Reported, Securities And Loans Receivable Pledged As Collateral + References No definition available. + Details
Name: | isba_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesAndLoansReceivablePledgedAsCollateral
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_DebtDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for debt facilities other than FHLB loans, repurchase agreements and letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
Name: | us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForOtherDebtFacilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for repurchase agreements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
Name: | us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_ShortTermDebtLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=isba_StateandLocalFundsPurchasedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_MortgageBackedSecuritiesOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |