Note 2 - Marketable Securities - Summary of Unrealized Gains and Losses on Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 03, 2019	Feb. 25, 2018
Amortized cost basis	$ 80,651	$ 91,791
Gross unrealized gains	51
Gross unrealized losses	85	1,814
US Treasury and Government [Member]
Amortized cost basis	68,727	80,116
Gross unrealized gains	44
Gross unrealized losses	53	1,755
Debt Security, Corporate, US [Member]
Amortized cost basis	11,924	11,675
Gross unrealized gains	7
Gross unrealized losses	$ 32	$ 59