Investments - Unrealized Gains and Losses and Fair Value (Details) - USD ($) $ in Thousands	Oct. 26, 2019	Apr. 27, 2019
Summary of investments
Gross Unrealized Gains	$ 2,501	$ 2,174
Gross Unrealized Losses	(17)	(124)
Fair Value	59,510	57,421
Equity securities
Summary of investments
Gross Unrealized Gains	1,939	1,841
Fair Value	20,018	19,535
Fixed income
Summary of investments
Gross Unrealized Gains	186	75
Gross Unrealized Losses	(17)	(111)
Fair Value	34,477	33,217
Other
Summary of investments
Gross Unrealized Gains	376	258
Gross Unrealized Losses	0	(13)
Fair Value	$ 5,015	$ 4,669