Note 3 - Marketable Securities - Summary of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Aug. 30, 2015	Mar. 01, 2015
US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities (Note 3)	$ 108,384	$ 119,493
US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities (Note 3)	0	0
US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities (Note 3)	0	0
US Treasury and Government [Member]
Marketable securities (Note 3)	108,384	119,493
Domestic Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities (Note 3)	31,700	7,084
Domestic Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities (Note 3)	0	4,018
Domestic Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities (Note 3)	0	0
Domestic Corporate Debt Securities [Member]
Marketable securities (Note 3)	31,700	11,102
Fair Value, Inputs, Level 1 [Member]
Marketable securities (Note 3)	140,084	126,577
Fair Value, Inputs, Level 2 [Member]
Marketable securities (Note 3)	0	4,018
Fair Value, Inputs, Level 3 [Member]
Marketable securities (Note 3)	0	0
Marketable securities (Note 3)	$ 140,084	$ 130,595	[1]

[1] The balance sheet at March 1, 2015 has been derived from the audited financial statements at that date.