Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total Par Value Of Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance, period start at Jun. 30, 2015	$ 7,480	$ 18,827	$ 162,176	$ (1,736)	$ 186,747
Balance, period end at Jun. 30, 2016	7,700	23,259	180,919	(2,228)	$ 209,650
Dividends declared per common share					$ 0.72
Issuance of common stock:
Stock options exercised, net	184	1,407			$ 1,591
Unrealized gain on available for sale investments, net of tax				128	128
Long-term incentive compensation	27	858			885
Stock-based compensation	9	406			415
Excess tax benefit from stock-based payment arrangements		(1,761)			(1,761)
Minimum pension liability adjustment, net of tax				(620)	(620)
Cash dividends declared			(5,494)		(5,494)
Net income			24,237		24,237
Balance, period start at Jun. 30, 2015	7,480	18,827	162,176	(1,736)	186,747
Balance, period end at Jun. 30, 2018	7,868	26,321	209,553	(2,044)	241,698
Issuance of common stock:
Excess tax benefit from stock-based payment arrangements					0
Balance, period start at Jun. 30, 2016	7,700	23,259	180,919	(2,228)	209,650
Balance, period end at Jun. 30, 2017	7,822	26,186	198,465	(1,713)	$ 230,760
Dividends declared per common share					$ 0.80
Issuance of common stock:
Stock options exercised, net	79	999			$ 1,078
Unrealized gain on available for sale investments, net of tax				36	36
Long-term incentive compensation	35	(213)			(178)
Stock-based compensation	8	647			655
Excess tax benefit from stock-based payment arrangements		1,494			1,494
Minimum pension liability adjustment, net of tax				479	479
Cash dividends declared			(6,240)		(6,240)
Net income			23,786		23,786
Balance, period end at Jun. 30, 2018	7,868	26,321	209,553	(2,044)	$ 241,698
Dividends declared per common share					$ 0.88
Issuance of common stock:
Stock options exercised, net	17	216			$ 233
Unrealized gain on available for sale investments, net of tax				(38)	(38)
Long-term incentive compensation	20	(858)			(838)
Stock-based compensation	9	777			786
Minimum pension liability adjustment, net of tax				41	41
Cash dividends declared			(6,912)		(6,912)
Net income			17,666		17,666
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			$ 334	$ (334)