CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosure [Abstract]
Net investment hedge currency translation adjustment, tax	$ (21,228)	$ 31,769
Changes in unrealized losses on marketable securities, tax	1,992	(3,729)	$ 2,023
Actuarial gains (losses), tax	$ (1)	$ (121)	$ (77)