Note 3 - Marketable Securities - Summary of Unrealized Gains and Losses on Available-for-sale Securities (Details) - USD ($) $ in Thousands	Nov. 27, 2022	Feb. 27, 2022
U.S. Treasury and other government securities	$ 104,560	$ 100,241
U.S. Treasury and other government securities	0	10
U.S. Treasury and other government securities	5,867	2,701
US Treasury and Government [Member]
U.S. Treasury and other government securities	85,196	65,177
U.S. Treasury and other government securities	0	5
U.S. Treasury and other government securities	5,684	2,570
Debt Security, Corporate, US [Member]
U.S. Treasury and other government securities	19,364	35,064
U.S. Treasury and other government securities	0	5
U.S. Treasury and other government securities	$ 183	$ 131