Note 8 - Financial Instruments and Investments in Securities (Tables)

12 Months Ended

Mar. 31, 2018

Notes Tables

Debt Securities, Held-to-maturity [Table Text Block]

	As of March 31, 2017
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Short-term investments:
Corporate bonds	$	10,120	$	-	$	(1	)	$	10,119
Time deposits		518,628		148		-			518,776
	$	528,748	$	148	$	(1	)	$	528,895

	As of March 31, 2018
	Cost		Gross Unrealized Gains			Gross Unrealized Losses		Estimated Fair Value
Short-term investments:
Commercial Paper	$	10,597	$	(1	)	$	-	$	10,596
Time deposits		269,190		203			-		269,393
	$	279,787	$	202		$	-	$	279,989

Investments Classified by Contractual Maturity Date [Table Text Block]

	Held-to-Maturity
	Amortized Cost		Estimated Fair Value
Due in one year or less	$	279,787	$	279,989
Due after one year through five years		-		-
Total	$	279,787	$	279,989