Note 4 - Financial Instruments and Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Aug. 31, 2019	Aug. 25, 2018	Nov. 24, 2018
Short-term Investments, Total	$ 17,643		$ 22,643
Certificates of Deposit Terms	9 months
Proceeds from Sale of Short-term Investments	$ 5,000	$ 482
Minimum [Member]
Interest Rate of Certificates of Deposit	0.85%
Maximum [Member]
Interest Rate of Certificates of Deposit	2.70%
Weighted Average [Member]
Certificates of Deposit Terms	4 months
Interest Rate of Certificates of Deposit	2.31%
Certificates of Deposit [Member]
Short-term Investments, Total	$ 17,643		$ 22,643
Proceeds from Sale of Short-term Investments	$ 5,000	$ 482