Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Open Market Repurchases [Member] Common Stock Outstanding [Member]	Open Market Repurchases [Member] Additional Paid-in Capital [Member]	Open Market Repurchases [Member] AOCI Attributable to Parent [Member]	Open Market Repurchases [Member] Retained Earnings [Member]	Open Market Repurchases [Member] Treasury Stock, Common [Member]	Open Market Repurchases [Member]	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Treasury Stock, Common [Member]	Total
Balance (in shares) at Sep. 30, 2023							71,294,247
Balance at Sep. 30, 2023							$ 713	$ 1,156,160	$ (62,426)	$ 1,641,009	$ (200,956)	$ 2,534,500
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)							144,894
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes							$ 2	(2)	0	0	0	0
Stock-based compensation							0	3,202	0	0	0	3,202
Net loss							0	0	0	(15,724)	0	(15,724)
Net investment hedge currency translation adjustment, net of tax							0	0	(13,368)	0	0	(13,368)
Foreign currency translation adjustments							0	0	46,494	0	0	46,494
Changes in unrealized losses on marketable securities, net of tax							0	0	2,524	0	0	2,524
Actuarial loss on pension plans, net of tax							$ 0	0	(8)	0	0	(8)
Balance (in shares) at Dec. 31, 2023							69,180,281
Balance at Dec. 31, 2023							$ 692	1,045,427	(26,784)	1,625,285	(200,956)	2,443,664
Shares repurchases (in shares)	(2,258,860)
Share repurchases		$ 0	$ 0	$ 0	$ (113,956)	$ (113,956)
Retirement of treasury shares							$ (23)	(113,933)	0	0	113,956	0
Balance (in shares) at Sep. 30, 2024							59,031,953
Balance at Sep. 30, 2024							$ 590	505,958	(13,464)	1,476,839	(200,956)	1,768,967
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)							121,804
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes							$ 2	(2)	0	0	0	0
Stock-based compensation							0	5,112	0	0	0	5,112
Net loss							0	0	0	(13,340)	0	(13,340)
Net investment hedge currency translation adjustment, net of tax							0	0	5,412	0	0	5,412
Foreign currency translation adjustments							0	0	(47,298)	0	0	(47,298)
Changes in unrealized losses on marketable securities, net of tax							0	0	163	0	0	163
Actuarial loss on pension plans, net of tax							$ 0	0	(50)	0	0	(50)
Balance (in shares) at Dec. 31, 2024							59,153,757
Balance at Dec. 31, 2024							$ 592	$ 511,068	$ (55,237)	$ 1,463,499	$ (200,956)	$ 1,718,966