Note 3 - Marketable Securities - Summary of Available-for-sale Securities (Details) - USD ($) $ in Thousands	May 28, 2023	Feb. 26, 2023
Available-for-sale securities	$ 75,269	$ 101,203
Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities	75,269	101,203
Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities	0	0
Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities	0	0
US Treasury and Government [Member]
Available-for-sale securities	70,284	83,859
US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities	70,284	83,859
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	4,985	17,344
Debt Security, Corporate, US [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities	4,985	17,344
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