XML 112 R100.htm IDEA: XBRL DOCUMENT
v3.20.4

Accumulated Other Comprehensive Income (Loss) (Components of unrealized holding gains on AFS securities) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |
Unrealized gains (losses) arising during the period |  | $ 7,474 | $ 12,276 | $ (7,229) |
Reclassification adjustment for net realized (gains) losses included in net income |  | (71) | (6) | 0 |
Comprehensive income (loss) before income tax (expense) benefit |  | 7,403 | 12,270 | (7,229) |
Tax effect | [1] | (1,530) | (2,458) | 1,415 |
Unrealized gains (losses), net of tax |  | 5,873 | 9,812 | (5,814) |
Unrealized Holding Gains (Losses) on AFS Securities [Member] |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |
Unrealized gains (losses) arising during the period |  | 7,474 | 12,276 | (7,229) |
Reclassification adjustment for net realized (gains) losses included in net income |  | (71) | (6) | 0 |
Comprehensive income (loss) before income tax (expense) benefit |  | 7,403 | 12,270 | (7,229) |
Tax effect | [1] | (1,530) | (2,458) | 1,415 |
Unrealized gains (losses), net of tax |  | 5,873 | 9,812 | (5,814) |
Unrealized Holding Gains (Losses) on AFS Securities [Member] | Auction Rate Money Market Preferred and Preferred Stocks [Member] |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |
Unrealized gains (losses) arising during the period |  | 118 | 565 | (495) |
Reclassification adjustment for net realized (gains) losses included in net income |  | 0 | 0 | 0 |
Comprehensive income (loss) before income tax (expense) benefit |  | 118 | 565 | (495) |
Tax effect |  | 0 | 0 | 0 | [1]
Unrealized gains (losses), net of tax |  | 118 | 565 | (495) |
Unrealized Holding Gains (Losses) on AFS Securities [Member] | All Other AFS Securities [Member] |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |
Unrealized gains (losses) arising during the period |  | 7,356 | 11,711 | (6,734) |
Reclassification adjustment for net realized (gains) losses included in net income |  | (71) | (6) | 0 |
Comprehensive income (loss) before income tax (expense) benefit |  | 7,285 | 11,705 | (6,734) |
Tax effect |  | (1,530) | (2,458) | 1,415 | [1]
Unrealized gains (losses), net of tax |  | $ 5,755 | $ 9,247 | $ (5,319) |
[1] | See “Note 17 – Accumulated Other Comprehensive Income (Loss)” in the accompanying notes to consolidated financial statements for tax effect reconciliation.

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

X
- Definition Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569643-111683 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683 + Details
Name: | us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569643-111683 + Details
Name: | us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e689-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27357-111563 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 17A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL34724391-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27357-111563 + Details
Name: | us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=isba_AuctionRateMoneyMarketPreferredStocksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=isba_AvailableforsaleSecuritiesExcludingAuctionRateMoneyMarketPreferredandPreferredStocksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |