Condensed Consolidated Statement of Shareholders' Equity - 3 months ended Sep. 30, 2017 - USD ($) $ in Thousands	Total	Common Stock [Member]	Common Class B [Member]	Common Stock [Member] Common Stock [Member]	Common Stock [Member] Common Class B [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Common Stock [Member]	Retained Earnings [Member] Common Class B [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Jun. 30, 2017	$ 995,972			$ 39,433	$ 5,119	$ 54,726	$ 915,703			$ (19,009)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	33,441						33,441
Other comprehensive income, net of income taxes	583									583
Shares issued under incentive plans, net of forfeitures	11,998			423		11,575
Purchases of Company stock	(17,693)			(299)		(17,394)
Share-based compensation	6,682					6,682
Dividends paid		$ (20,960)	$ (2,662)					$ (20,960)	$ (2,662)
Ending balance at Sep. 30, 2017	1,007,761			$ 39,557	$ 5,119	56,631	$ 924,880			$ (18,426)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment for adoption of Accounting Standards Update 2016-09	$ 400					$ 1,042			$ (642)