XML 117 R63.htm IDEA: XBRL DOCUMENT v3.20.1

Loans and ALLL (Summary of information pertaining to TDRs) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	11	45
Pre-Modification Recorded Investment	$ 4,491	$ 8,379
Post-Modification Recorded Investment	$ 4,491	$ 8,356
Commercial other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	4
Pre-Modification Recorded Investment	$ 1,188	$ 1,360
Post-Modification Recorded Investment	$ 1,188	$ 1,360
Agricultural other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	7	31
Pre-Modification Recorded Investment	$ 3,286	$ 6,318
Post-Modification Recorded Investment	$ 3,286	$ 6,295
Residential real estate senior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	10
Pre-Modification Recorded Investment	$ 17	$ 701
Post-Modification Recorded Investment	$ 17	$ 701
Below Market Interest Rate and Extension of Amortization Period [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	9	23
Pre-Modification Recorded Investment	$ 3,302	$ 5,377
Below Market Interest Rate and Extension of Amortization Period [Member] | Commercial other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	3
Pre-Modification Recorded Investment	$ 1,188	$ 1,186
Below Market Interest Rate and Extension of Amortization Period [Member] | Agricultural other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	5	13
Pre-Modification Recorded Investment	$ 2,097	$ 3,693
Below Market Interest Rate and Extension of Amortization Period [Member] | Residential real estate senior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	7
Pre-Modification Recorded Investment	$ 17	$ 498
Interest Rate Below Market Reduction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	2	22
Pre-Modification Recorded Investment	$ 1,189	$ 3,002
Interest Rate Below Market Reduction [Member] | Commercial other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1
Pre-Modification Recorded Investment	$ 0	$ 174
Interest Rate Below Market Reduction [Member] | Agricultural other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	2	18
Pre-Modification Recorded Investment	$ 1,189	$ 2,625
Interest Rate Below Market Reduction [Member] | Residential real estate senior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	3
Pre-Modification Recorded Investment	$ 0	$ 203

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_FinancingReceivableModificationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_CommercialOtherPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_AgriculturalOtherPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_ResidentialSeniorLiensFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=isba_BelowMarketInterestRateAndExtensionOfAmortizationPeriodMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_InterestRateBelowMarketReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: