Note 5 - Stock-based Compensation (Tables)

12 Months Ended

Mar. 31, 2020

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended March 31
	2020			2019
Risk-free interest rate		1.7	%		2.9	%
Expected volatility		37	%		33	%
Expected life (years)		4.6			4.5
Dividend yield		5.9	%		3.7	%

Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

Ranges of Exercise Prices			Number Outstanding		Weighted Average Exercise Price		Weighted Remaining Contractual Life (years)
$49.86	-	$67.69		16,000	$	61.37		6.0
$76.13	-	$107.86		8,000		92.00		7.9
				24,000	$	71.58		6.6

Share-based Payment Arrangement, Activity [Table Text Block]

	Option Shares Reserved			Options Outstanding			Weighted Average Option Exercise Price
At March 31, 2018		139,230			22,000		$	61.19
Granted		(4,000	)		4,000		$	107.86
Exercised		-			(4,000	)	$	54.49
At March 31, 2019		135,230			22,000		$	70.89
Granted		(4,000	)		4,000		$	67.65
Exercised		-			(2,000	)	$	56.18
At March 31, 2020		131,230			24,000		$	71.58