Note 5 - Supplemental Financial Information - Accrued Rebate Activity (Details) $ in Thousands	9 Months Ended
Oct. 29, 2016 USD ($)
Beginning balance	$ 2,864
Charged as a reduction of revenue	3,499
Reversal of unclaimed rebates	(3)
Payments	(4,564)
Ending balance	$ 1,796

Represents the aggregate increase in the liability for accrued rebates for rebates charged as a reduction of revenue.

No definition available.

Name:	sigm_AccruedRebatesChargedAsAReductionOfRevenue
Namespace Prefix:	sigm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration