Income Taxes - Tax Acts (Details) $ in Millions	12 Months Ended
Mar. 31, 2019 USD ($)
Income Taxes
Income tax benefit to re-measure deferred tax liabilities	$ 0.2

Amount of reasonable estimate for income tax expense (benefit) from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

No definition available.

Name:	tess_TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefitIncompleteAccountingProvisionalAmount
Namespace Prefix:	tess_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration