Fair Value Measurements (Details) - USD ($) $ in Thousands	Oct. 24, 2015	Apr. 25, 2015
Assets
Transfers from Level 1 to Level 2	$ 0	$ 0
Transfers from Level 2 to Level 1	0	0
Level 1 | Recurring basis
Assets
Available-for-sale securities	1,415	1,552
Total		1,552
Level 2 | Recurring basis
Assets
Available-for-sale securities	$ 44,314	58,516
Trading securities		1,127
Total		$ 59,643