Earnings Per Share (Reconciliation of Net Earnings to Net Earnings Per Share Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net earnings	$ 208,649	$ 240,395	$ 259,602
Denominator:
Basic shares outstanding	63,287	62,267	61,950
Dilutive effect of stock options and restricted stock units	2,268	1,942	2,548
Diluted shares outstanding	65,555	64,209	64,498
Income per common share:
Basic earnings per share	$ 3.30	$ 3.86	$ 4.19
Diluted earnings per share	$ 3.18	$ 3.74	$ 4.02