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, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Net income	$ 27,621	$ 14,471	$ 102,927	$ 86,827
Net income available to participating securities	(58)	(23)	(206)	(149)
Net income available to common shareholders	$ 27,563	$ 14,448	$ 102,721	$ 86,678
Weighted average common shares outstanding - basic (in shares)	27,405	27,379	27,399	27,369
Incremental share effect from:
Nonparticipating restricted stock (in shares)	2	1	3	3
Stock-settled stock appreciation rights (in shares)	51	62	54	66
Weighted average common shares outstanding - diluted (in shares)	27,458	27,442	27,456	27,438
Net income per common share - basic (in dollars per share)	$ 1.01	$ 0.53	$ 3.75	$ 3.17
Net income per common share - diluted (in dollars per share)	$ 1.00	$ 0.53	$ 3.74	$ 3.16