Note 3 - Marketable Securities - Summary of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Aug. 28, 2022	Feb. 27, 2022
Available-for-sale securities	$ 98,630	$ 97,550
Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities	98,630	97,550
Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities	0	0
Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities		0
US Treasury and Government [Member]
Available-for-sale securities	71,438	62,612
US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities	71,438	62,612
US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities	0	0
US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities	0	0
Debt Security, Corporate, US [Member]
Available-for-sale securities	27,192	34,938
Debt Security, Corporate, US [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities	27,192	34,938
Debt Security, Corporate, US [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities	0	0
Debt Security, Corporate, US [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities	$ 0	$ 0