Note 13 - Stock-based Compensation and Purchase Plans (Tables)

12 Months Ended

Jun. 30, 2020

Notes Tables

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Restricted Stock Awards
	Number			Aggregate
	of			Intrinsic
	Shares			Value
Outstanding, June 30, 2019		128,042		$	9,365,632
Granted		75,505
Exercised / vested		(32,953	)	$	(528,957	)
Canceled		(24,579	)
Outstanding, June 30, 2020		146,015		$	8,403,221

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

	2020			2019			2018
Risk-free interest rates		1.42	%		2.63	%		1.55	%
Expected life of option grants (in years)		3			3			3
Expected volatility of underlying stock		32.0	%		25.1	%		25.6	%
Expected quarterly dividends (per share)	$	0.20		$	0.18		$	0.16

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

	Annual Component								Performance Stock Units
				Weighted
	Number			Average		Aggregate			Number			Aggregate
	of			Exercise		Intrinsic			of			Intrinsic
	Shares			Price		Value			Shares			Value
Non-vested, June 30, 2019		34,950		$	69.07	$	(496,674	)		69,052		$	6,529,012
Granted		14,883			51.56					42,976
Vested		(17,108	)		62.86	$	7,471			(12,225	)	$	1,025,922
Forfeited		(338	)		66.10					(20,491	)
Non-vested, June 30, 2020		32,387		$	64.33	$	(685,647	)		79,312		$	6,731,430