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, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2021	Mar. 31, 2020
Accounting Policies [Abstract]
Net income	$ 28,897	$ 44,630	$ 37,079	$ 22,429	$ 43,424	$ 40,745	$ 110,606	$ 106,598
Net income available to participating securities	(56)			(48)			(223)	(216)
Net income available to common shareholders	$ 28,841			$ 22,381			$ 110,383	$ 106,382
Weighted average common shares outstanding - basic (in shares)	27,483			27,457			27,474	27,447
Incremental share effect from:
Nonparticipating restricted stock (in shares)	2			1			2	2
Stock-settled stock appreciation rights (in shares)	41			43			37	53
Weighted average common shares outstanding - diluted (in shares)	27,526			27,501			27,513	27,502
Net income per common share - basic (in dollars per share)	$ 1.05			$ 0.82			$ 4.02	$ 3.88
Net income per common share - diluted (in dollars per share)	$ 1.05			$ 0.81			$ 4.01	$ 3.87