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v3.20.1

Commitments and Credit Risk (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2020 | Dec. 31, 2019
Other Commitments [Line Items] |  |
Loan commitments | $ 295.9 | $ 254.4
Capital committed to Small Business Investment Company fund, not contributed | 1.7 |
Capital Addition Purchase Commitments |  |
Other Commitments [Line Items] |  |
Construction related contract commitment | 65.1 |
Construction related contract commitment, not yet incurred | $ 58.9 |
Construction related contract commitment, term | 2 years |

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- Definition Other Commitment, Not Incurred + References No definition available. + Details
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Namespace Prefix: | inbk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Other Commitment, Term + References No definition available. + Details
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- Definition Other Commitments, Capital Committed To Small Business Investment Company Fund + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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- Definition Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | credit
Period Type: | instant

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- Definition Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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Period Type: | instant

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- 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
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- Details
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Balance Type: |
Period Type: |