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, 2020	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Net income (loss)	$ 130,695	$ (27,460)	$ 51,987
Weighted average shares outstanding	115,663	117,724	116,390
Dilutive effect of employee stock options, restricted shares and restricted stock units	604	0	1,768
Diluted weighted average shares outstanding	116,267	117,724	118,158
Basic earnings (loss) per share	$ 1.13	$ (0.23)	$ 0.45
Diluted earnings (loss) per share	$ 1.12	$ (0.23)	$ 0.44