Note 11 - Employee Benefit Plans (Details Textual) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
401(k) Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	10.00%
Defined Contribution Plan Maximum Annual Employer Matching Contribution Per Emplyee Amount	$ 5
Defined Contribution Plan Employer Matching Contribution Vesting Period (Year)	4 years
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 165	$ 190
The Ambrell Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	2.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 17	$ 23
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	25.00%

Defined contribution plan employer matching contribution vesting period.

No definition available.

Name:	intt_DefinedContributionPlanEmployerMatchingContributionVestingPeriod
Namespace Prefix:	intt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Maximum dollar amount of employer's annual matching contribution to a defined contribution plan

No definition available.

Name:	intt_DefinedContributionPlanMaximumAnnualEmployerMatchingContributionPerEmplyeeAmount
Namespace Prefix:	intt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage employer matches of the employee's percentage contribution matched.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_RetirementPlanNameAxis=intt_The401KPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanNameAxis=intt_TheAmbrellPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: