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, 2019	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Net income	$ 43,424	$ 40,745	$ 47,907	$ 39,028	$ 84,169	$ 86,935
Net income available to participating securities	(68)		(96)		(133)	(176)
Net income available to common shareholders	$ 43,356		$ 47,811		$ 84,036	$ 86,759
Weighted average common shares outstanding - basic (in shares)	27,443		27,435		27,443	27,429
Incremental share effect from:
Nonparticipating restricted stock (in shares)	2		2		2	4
Stock-settled stock appreciation rights (in shares)	44		129		58	107
Weighted average common shares outstanding - diluted (in shares)	27,489		27,566		27,503	27,540
Net income per common share - basic (in dollars per share)	$ 1.58		$ 1.74		$ 3.06	$ 3.16
Net income per common share - diluted (in dollars per share)	$ 1.58		$ 1.73		$ 3.06	$ 3.15