Fair Value Measurements - Hierarchy and Transfers (Details) - USD ($) $ in Thousands	Apr. 24, 2021	Apr. 25, 2020
Assets
Total assets	$ 55,404	$ 48,022
Recurring basis
Assets
Marketable securities	45,293	38,206
Held-to-maturity investments	2,532	3,337
Cost basis investments	7,579	6,479
Total assets	55,404	48,022
Liabilities
Contingent consideration liability	14,100	0
Recurring basis | Level 1
Assets
Marketable securities	119	0
Held-to-maturity investments	2,532	3,337
Cost basis investments	0	0
Total assets	2,651	3,337
Liabilities
Contingent consideration liability	0	0
Recurring basis | Level 2
Assets
Marketable securities	37,572	31,691
Held-to-maturity investments	0	0
Cost basis investments	0	0
Total assets	37,572	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	14,100	0
Recurring basis | NAV
Assets
Marketable securities	7,602	6,515
Held-to-maturity investments	0	0
Cost basis investments	0	0
Total assets	7,602	6,515
Liabilities
Contingent consideration liability	$ 0	$ 0