Loans And Leases Receivable, Reclassified, Gross

No definition available.

Name:	inbk_LoansAndLeasesReceivableReclassifiedGross
Namespace Prefix:	inbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

+ Details

Name:	us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

+ Details

Name:	us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524

+ Details

Name:	us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

Name:	us-gaap_LoansAndLeasesReceivableNetReportedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533

+ Details

Name:	us-gaap_UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiums
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans - Categories (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	$ 2,909,342		$ 2,919,981
Net deferred loan origination costs and premiums and discounts on purchased loans and other	64,332		43,566
Total loans	2,973,674		2,963,547
Allowance for loan losses	(24,465)	$ (22,857)	(21,840)	$ (19,976)	$ (18,841)	$ (17,896)
Net loans	2,949,209		2,941,707
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(1,477)	(1,670)	(1,521)	(1,795)	(1,351)	(1,384)
Owner-occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(846)	(645)	(561)	(624)	(847)	(891)
Investor commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(130)	(128)	(109)	(169)	(103)	(61)
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(721)	(460)	(380)	(302)	(267)	(251)
Single tenant lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(11,318)	(10,755)	(11,175)	(9,661)	(9,368)	(8,827)
Public finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(1,542)	(1,483)	(1,580)	(1,763)	(1,650)	(1,670)
Healthcare finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(4,762)	(4,318)	(3,247)	(2,293)	(1,731)	(1,264)
Small business lending
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(251)	(265)	(54)	(129)	(93)	(95)
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(539)	(500)	(657)	(662)	(1,044)	(1,079)
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(51)	(53)	(46)	(48)	(49)	(53)
Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	(2,828)	$ (2,580)	(2,510)	$ (2,530)	$ (2,338)	$ (2,321)
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	2,386,342		2,286,517
Commercial Portfolio Segment \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	81,687		96,420
Commercial Portfolio Segment \| Owner-occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	86,897		86,726
Loans reclassified	13,300
Commercial Portfolio Segment \| Investor commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	13,286		12,567
Commercial Portfolio Segment \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	77,591		60,274
Commercial Portfolio Segment \| Single tenant lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	980,292		995,879
Commercial Portfolio Segment \| Public finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	647,107		687,094
Commercial Portfolio Segment \| Healthcare finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	380,956		300,612
Commercial Portfolio Segment \| Small business lending
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	118,526		46,945
Consumer Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	523,000		633,464
Consumer Portfolio \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	208,728		313,849
Consumer Portfolio \| Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	22,640		24,306
Consumer Portfolio \| Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	291,632		295,309
Interest rate swaps \| Commercial Portfolio Segment \| Public finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	$ 46,000		$ 21,400