Income Taxes - Income Before Income Taxes and Taxes on Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Before Income Taxes [Abstract]
Domestic	$ (129,814)	$ 94,002	$ (45,364)
Foreign	75,020	79,345	108,470
(Loss) income before income taxes	(54,794)	173,347	63,106
U.S. federal and state:
Current	29,712	20,733	23,461
Deferred	(39,609)	(7,048)	(23,182)
Total	(9,897)	13,685	279
Foreign:
Current	25,417	21,053	27,580
Deferred	(1,737)	(4,219)	(3,968)
Total	23,680	16,834	23,612
Total U.S. and foreign	$ 13,783	$ 30,519	$ 23,891