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, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2020	Mar. 31, 2019
Accounting Policies [Abstract]
Net income	$ 22,429	$ 43,424	$ 40,745	$ 30,604	$ 47,907	$ 39,028	$ 106,598	$ 117,539
Net income available to participating securities	(48)			(52)			(216)	(212)
Net income available to common shareholders	$ 22,381			$ 30,552			$ 106,382	$ 117,327
Weighted average common shares outstanding - basic (in shares)	27,457			27,448			27,447	27,436
Incremental share effect from:
Nonparticipating restricted stock (in shares)	1			1			2	3
Stock-settled stock appreciation rights (in shares)	43			100			53	104
Weighted average common shares outstanding - diluted (in shares)	27,501			27,549			27,502	27,543
Net income per common share - basic (in dollars per share)	$ 0.82			$ 1.11			$ 3.88	$ 4.28
Net income per common share - diluted (in dollars per share)	$ 0.81			$ 1.11			$ 3.87	$ 4.26