Note 3 - Marketable Securities (Tables)

3 Months Ended

May. 31, 2015

Notes Tables

Schedule of Fair Value of Separate Accounts by Major Category of Investment [Table Text Block]

	May 31, 2015
	Total		Level 1		Level 2		Level 3
U.S. Treasury and other government securities	$	135,577	$	135,577	$	-	$	-
U.S. corporate debt securities		31,882		27,880		4,002		-
Total marketable securities	$	167,459	$	163,457	$	4,002	$	-

	March 1, 2015
	Total		Level 1		Level 2		Level 3
U.S. Treasury and other government securities	$	119,493	$	119,493	$	-	$	-
U.S. corporate debt securities		11,102		7,084		4,018		-
Total marketable securities	$	130,595	$	126,577	$	4,018	$	-

Schedule of Unrealized Loss on Investments [Table Text Block]

	Amortized Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses
May 31, 2015:
U.S. Treasury and other government securities	$	135,131	$	471	$	26
U.S. corporate debt securities		31,914		1		32
Total marketable securities	$	167,045	$	472	$	58
March 1, 2015:
U.S. Treasury and other government securities	$	119,191	$	314	$	12
U.S. corporate debt securities		11,097		5		-
Total marketable securities	$	130,288	$	319	$	12

Investments Classified by Contractual Maturity Date [Table Text Block]

Due in one year or less	$	90,008
Due after one year through five years		77,451
	$	167,459