Segment Information - Geographic Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 29, 2017	Apr. 30, 2016	Apr. 25, 2015
Geographic Information
Long-lived assets	$ 262,989	$ 218,464	$ 195,583
Geographic concentration | Sales
Geographic Information
Percentage of sales	100.00%	100.00%	100.00%
Domestic/United States
Geographic Information
Long-lived assets	$ 239,198	$ 211,021	$ 187,224
Domestic/United States | Geographic concentration | Sales
Geographic Information
Percentage of sales	88.00%	89.00%	87.00%
International
Geographic Information
Long-lived assets	$ 23,791	$ 7,443	$ 8,359
Canada | Geographic concentration | Sales
Geographic Information
Percentage of sales	7.00%	7.00%	7.00%
Other | Geographic concentration | Sales
Geographic Information
Percentage of sales	5.00%	4.00%	6.00%