Fair Value Measurements - Hierarchy and Transfers (Details) - USD ($) $ in Thousands	Jan. 23, 2021	Apr. 25, 2020
Assets
Total assets	$ 53,051	$ 48,022
Recurring basis
Assets
Marketable securities	42,829	38,206
Held-to-maturity investments	2,643	3,337
Cost basis investments	7,579	6,479
Total assets	53,051	48,022
Liabilities
Contingent consideration liability	12,500	0
Recurring basis | Level 1
Assets
Marketable securities	0	0
Held-to-maturity investments	2,643	3,337
Cost basis investments	0	0
Total assets	2,643	3,337
Liabilities
Contingent consideration liability	0	0
Recurring basis | Level 2
Assets
Marketable securities	34,766	31,691
Held-to-maturity investments	0	0
Cost basis investments	0	0
Total assets	34,766	31,691
Liabilities
Contingent consideration liability	0	0
Recurring basis | Level 3
Assets
Marketable securities	0	0
Held-to-maturity investments	0	0
Cost basis investments	7,579	6,479
Total assets	7,579	6,479
Liabilities
Contingent consideration liability	12,500	0
Recurring basis | NAV
Assets
Marketable securities	8,063	6,515
Held-to-maturity investments	0	0
Cost basis investments	0	0
Total assets	8,063	6,515
Liabilities
Contingent consideration liability	$ 0	$ 0