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		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Accounting Policies [Abstract]
Net income	$ 14,471	$ 29,011	$ 86,827	$ 91,150
Net income available to participating securities	(23)	(54)	(149)	(216)
Net income available to common shareholders	$ 14,448	$ 28,957	$ 86,678	$ 90,934
Weighted average common shares outstanding - basic (in shares)	27,379	27,338	27,369	27,329
Incremental share effect from:
Nonparticipating restricted stock (in shares)	1	2	3	3
Stock-settled stock appreciation rights (in shares)	62	36	66	33
Weighted average common shares outstanding - diluted (in shares)	27,442	27,376	27,438	27,365
Net income per common share - basic (in dollars per share)	$ 0.53	$ 1.06	$ 3.17	$ 3.33
Net income per common share - diluted (in dollars per share)	$ 0.53	$ 1.06	$ 3.16	$ 3.32