Summary Of Significant Accounting Policies (Schedule Of Basic And Diluted Net Income Per Common Share Calculations) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Net income	$ 45,920	$ 38,956	$ 75,306	$ 72,356
Net income available to participating securities	(73)	(77)	(119)	(142)
Net income available to common shareholders	$ 45,847	$ 38,879	$ 75,187	$ 72,214
Weighted average common shares outstanding - basic (in shares)	27,396	27,366	27,396	27,364
Incremental share effect from:
Nonparticipating restricted stock (in shares)	3	3	4	4
Stock-settled stock appreciation rights (in shares)	61	72	56	67
Weighted average common shares outstanding - diluted (in shares)	27,460	27,441	27,456	27,435
Net income per common share - basic (in dollars per share)	$ 1.67	$ 1.42	$ 2.74	$ 2.64
Net income per common share - diluted (in dollars per share)	$ 1.67	$ 1.42	$ 2.74	$ 2.63