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

12 Months Ended

Jun. 30, 2018

Notes Tables

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Restricted Stock Awards
	Number			Aggregate
	of			Intrinsic
	Shares			Value
Outstanding, June 30, 2017		115,703		$	10,494,262
Granted		51,792
Exercised / vested		(37,970	)	$	757,216
Canceled		(9,515	)
Outstanding, June 30, 2018		120,010		$	12,258,515

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

	2018			2017			2016
Risk-free interest rates		1.55	%		0.71	%		1.10	%
Expected life of option grants (in years)		3			3			3
Expected volatility of underlying stock		25.6	%		25.7	%		26.6	%
Expected quarterly dividends (per share)	$	0.16		$	0.14		$	0.12

Share-based Compensation, Stock Options, 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, 2017		35,707		$	59.11	$	318,334		52,890		$	4,254,256
Granted		9,050		$	68.03				24,567
Vested		(10,930	)	$	55.76		428,893		(15,780	)	$	1,194,319
Forfeited		(2,067	)	$	60.62				(3,167	)
Non-vested, June 30, 2018		31,760		$	62.71		442,850		58,028		$	5,013,531