Investments - Unrealized Gains and Losses and Fair Value (Details) - USD ($) $ in Thousands	Apr. 27, 2019	Apr. 28, 2018
Summary of investments
Gross Unrealized Gains	$ 2,174	$ 2,243
Gross Unrealized Losses	(124)	(457)
Fair Value	57,421	59,354
Equity securities
Summary of investments
Gross Unrealized Gains	1,841	2,142
Gross Unrealized Losses		(39)
Fair Value	19,535	18,765
Fixed income
Summary of investments
Gross Unrealized Gains	75	29
Gross Unrealized Losses	(111)	(418)
Fair Value	33,217	36,312
Other
Summary of investments
Gross Unrealized Gains	258	72
Gross Unrealized Losses	(13)
Fair Value	$ 4,669	$ 4,277