Note 3 - Marketable Securities (Tables)

3 Months Ended

May 31, 2020

Notes Tables

Debt Securities, Available-for-sale [Table Text Block]

	May 31, 2020
	Total		Level 1		Level 2		Level 3
U.S. Treasury and other government securities	$	94,120	$	94,120	$	-	$	-
U.S. corporate debt securities		18,545		18,545		-		-
Total marketable securities	$	112,665	$	112,665	$	-

	March 1, 2020
	Total		Level 1		Level 2		Level 3
U.S. Treasury and other government securities	$	101,390	$	101,390	$	-	$	-
U.S. corporate debt securities		15,555		15,555		-		-
Total marketable securities	$	116,945	$	116,945	$	-	$	-

Schedule of Available-for-sale Securities Reconciliation [Table Text Block]

	Amortized Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses
May 31, 2020:
U.S. Treasury and other government securities	$	93,075	$	1,045	$	-
U.S. corporate debt securities		18,486		118		59
Total marketable securities	$	111,561	$	1,163	$	59
March 1, 2020:
U.S. Treasury and other government securities	$	100,626	$	764	$	-
U.S. corporate debt securities		15,473		82		-
Total marketable securities	$	116,099	$	846	$	-

Investments Classified by Contractual Maturity Date [Table Text Block]

Due in one year or less	$	37,690
Due after one year through five years		74,975
	$	112,665