CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)	Treasury Stock	Total
Beginning Balance at Sep. 30, 2022	$ 885	$ 1,992,017	$ (83,916)	$ 1,655,356	$ (200,956)	$ 3,363,386
Beginning Balance (in shares) at Sep. 30, 2022	88,482,125
Increase (Decrease) in Stockholders' Equity
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes					(4,629)	(4,629)
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)	123,926
Share repurchases					(500,000)	(500,000)
Share repurchases (in shares)	(6,090,134)
Retirement of treasury shares	$ (61)	(504,568)			504,629
Stock-based compensation		2,105				2,105
Net Income (Loss)				(11,235)		(11,235)
Net investment hedge currency translation adjustment, net of tax			(57,127)			(57,127)
Foreign currency translation adjustments			77,414			77,414
Changes in unrealized gains on marketable securities, net of tax			1,555			1,555
Other				(81)		(81)
Ending Balance at Dec. 31, 2022	$ 824	1,489,554	(62,074)	1,644,041	(200,956)	2,871,389
Ending Balance (in shares) at Dec. 31, 2022	82,515,917
Beginning Balance at Sep. 30, 2023	$ 713	1,156,160	(62,426)	1,641,009	(200,956)	$ 2,534,500
Beginning Balance (in shares) at Sep. 30, 2023	71,294,247					57,832,378
Increase (Decrease) in Stockholders' Equity
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes	$ 2	(2)
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)	144,894
Share repurchases					(113,956)	$ (113,956)
Share repurchases (in shares)	(2,258,860)
Retirement of treasury shares	$ (23)	(113,933)			113,956
Stock-based compensation		3,202				3,202
Net Income (Loss)				(15,724)		(15,724)
Net investment hedge currency translation adjustment, net of tax			(13,368)			(13,368)
Foreign currency translation adjustments			46,494			46,494
Changes in unrealized gains on marketable securities, net of tax			2,524			2,524
Actuarial loss on pension plans, net of tax			(8)			(8)
Ending Balance at Dec. 31, 2023	$ 692	$ 1,045,427	$ (26,784)	$ 1,625,285	$ (200,956)	$ 2,443,664
Ending Balance (in shares) at Dec. 31, 2023	69,180,281					55,718,412