Consolidated Statements of Comprehensive Income (loss) (Parenthetical) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 28, 2017	Oct. 29, 2016	Oct. 28, 2017	Oct. 29, 2016
Consolidated Statements of Comprehensive Loss
Unrealized gain on investments, net of deferred tax expense of $17 and $17 for the three months ended October 28, 2017 and October 29, 2016, respectively; and net of deferred tax expense of $19 and $29 for the six months ended October 28, 2017 and October 29, 2016, respectively	$ 17,000	$ 17,000	$ 19,000	$ 29