Investments - Unrealized Gains and Losses and Fair Value (Details) - USD ($) $ in Thousands	Oct. 29, 2016	Apr. 30, 2016
Summary of investments
Gross Unrealized Gains	$ 1,511	$ 1,408
Gross Unrealized Losses	(177)	(165)
Fair Value	51,018	46,976
Equity securities
Summary of investments
Gross Unrealized Gains	1,400	1,231
Gross Unrealized Losses	(126)	(135)
Fair Value	13,837	8,150
Fixed income
Summary of investments
Gross Unrealized Gains	110	176
Gross Unrealized Losses	(39)	(9)
Fair Value	34,293	36,527
Mutual funds
Summary of investments
Fair Value	434
Other
Summary of investments
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(12)	(21)
Fair Value	$ 2,454	$ 2,299