Shareholders' Equity and Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	May 02, 2020	Apr. 27, 2019	Apr. 28, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 2,265	$ 2,479	$ 2,635
Cost of sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	514	578	619
Selling
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	572	625	644
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	717	772	851
Product design and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 462	$ 504	$ 521