Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 29, 2017	Jul. 30, 2016	Jul. 29, 2017	Jul. 30, 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	$ 192	$ 459	625	$ 612
Ending Balance Accumulated other comprehensive income, net of tax	411		411
ChangeInUnrealizedGainsOnAvailableForSaleSecuritiesMember [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance Accumulated other comprehensive income, net of tax	219	953	(214)	800
Other Comprehensive Income Loss Before Reclassifications Net Of Tax	186	510	622	664
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax	6	(51)	3	(52)
Unrealized gain on available-for-sale securities, net of deferred income taxes	192	459	625	612
Ending Balance Accumulated other comprehensive income, net of tax	$ 411	$ 1,412	$ 411	$ 1,412