Investments - Unrealized Gains and Losses and Fair Value (Details) - USD ($) $ in Thousands	Jan. 25, 2020	Apr. 27, 2019
Summary of investments
Gross Unrealized Gains	$ 2,497	$ 2,174
Gross Unrealized Losses	(6,008)	(124)
Fair Value	50,814	57,421
Equity securities
Summary of investments
Gross Unrealized Gains	1,922	1,841
Fair Value	13,600	19,535
Fixed income
Summary of investments
Gross Unrealized Gains	199	75
Gross Unrealized Losses	(8)	(111)
Fair Value	31,962	33,217
Other
Summary of investments
Gross Unrealized Gains	376	258
Gross Unrealized Losses	0	(13)
Fair Value	$ 5,252	$ 4,669