Note 9 - Post-retirement Benefits (Details Textual)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Retirement Plan Minimum Age	65
Retirement Plan Lump Sum Cash Payment Per Year	$ 5,000
Retirement Plan Lump Sum Cash Payment Maximum	50,000
Retirement Plan Lump Sum Cash Payment Accrual	$ 50,000	$ 50,000

The amount contributed to an employee's post-retirement lump sum receipt for every year of the employee's service with the company.

No definition available.

Name:	ins_RetirementPlanLumpSumCashPaymentPerYear
Namespace Prefix:	ins_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant