Summary of Significant Accounting Policies (Earnings Per Share Basic And Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Net Income (Loss)	$ 245,540	$ 313,081	$ 476,923
Weighted average shares outstanding	118,341	117,194	116,836
Dilutive effect of employee stock options, restricted shares and restricted stock units	993	1,039	1,531
Diluted weighted average shares outstanding	119,334	118,233	118,367
Earnings per share-Basic	$ 2.07	$ 2.67	$ 4.08
Earnings per share-Diluted	$ 2.06	$ 2.65	$ 4.03