Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 28, 2017	Oct. 29, 2016	Oct. 28, 2017	Oct. 29, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance Accumulated other comprehensive income, net of tax			$ (214)
Unrealized gain on available-for-sale securities, net of deferred income taxes	$ (170)	$ (881)	455	$ (269)
Ending Balance Accumulated other comprehensive income, net of tax	241		241
ChangeInUnrealizedGainsOnAvailableForSaleSecuritiesMember [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance Accumulated other comprehensive income, net of tax	411	1,412	(214)	800
Other Comprehensive Income Loss Before Reclassifications Net Of Tax	(144)	(765)	478	(101)
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax	(26)	(116)	(23)	(168)
Unrealized gain on available-for-sale securities, net of deferred income taxes	(170)	(881)	455	(269)
Ending Balance Accumulated other comprehensive income, net of tax	$ 241	$ 531	$ 241	$ 531