Note 8 - Financial Instruments and Risks - Impact of Change in Interest Rates (Details) $ in Millions	12 Months Ended
Dec. 29, 2019 USD ($)
Ten Percent Increase In Interest Rate [Member]
10% increase in interest rate (millions)	$ 0.6
Ten Percent Decrease in Interest Rate [Member]
10% increase in interest rate (millions)	$ (0.6)

The effect on reported earnings from changes in the interest rate.

No definition available.

Name:	smtx_EffectOnEarningsChangeInInterestRates
Namespace Prefix:	smtx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration