Benefit Plans - Deferred Stock Rights (Details)	6 Months Ended
Jun. 30, 2014
Deferred Stock Rights
Outstanding, beginning of period	79,676
Granted	425
Exercised	0
Outstanding, end of period	80,101

It represents the deferred stock rights granted to directors during the period related to deferred stock plan.

No definition available.

Name:	inbk_DeferredStockRelatedToDirectorsDeferredStockPlanGrantedInPeriod
Namespace Prefix:	inbk_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration