CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock Share Repurchase Program, Accelerated Share Repurchase Programs	Common Stock Share Repurchase Program, Open Market Share Repurchase Programs	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)	Treasury Stock Share Repurchase Program, Accelerated Share Repurchase Programs	Treasury Stock Share Repurchase Program, Open Market Share Repurchase Programs	Treasury Stock	Share Repurchase Program, Accelerated Share Repurchase Programs	Share Repurchase Program, Open Market Share Repurchase Programs	Total
Beginning Balance at Sep. 30, 2021			$ 878	$ 1,976,112	$ 19,351	$ (470,051)			$ (200,956)			$ 1,325,334
Beginning Balance (in shares) at Sep. 30, 2021			87,808,922
Increase (Decrease) in Stockholders' Equity
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes			$ 7	3,454								3,461
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)			642,301
Stock-based compensation				10,715								10,715
Common stock dividends declared						(7,494)						(7,494)
Net investment hedge currency translation adjustment, net of tax					49,081							49,081
Foreign currency translation adjustments reclassed out of accumulated other comprehensive income related to discontinued operations					(16,567)							(16,567)
Foreign currency translation adjustments					(85,160)							(85,160)
Changes in unrealized gains (losses) on marketable securities, net of tax					(5,306)							(5,306)
Actuarial loss, net of tax					108							108
Net income (loss)						2,153,624						2,153,624
Other						(10)						(10)
Ending Balance at Jun. 30, 2022			$ 885	1,990,281	(38,493)	1,676,069			(200,956)			3,427,786
Ending Balance (in shares) at Jun. 30, 2022			88,451,223
Beginning Balance at Mar. 31, 2022			$ 885	1,986,796	(7,398)	1,685,649			(200,956)			3,464,976
Beginning Balance (in shares) at Mar. 31, 2022			88,450,083
Increase (Decrease) in Stockholders' Equity
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)			1,140
Stock-based compensation				3,485								3,485
Net investment hedge currency translation adjustment, net of tax					41,956							41,956
Foreign currency translation adjustments					(70,179)							(70,179)
Changes in unrealized gains (losses) on marketable securities, net of tax					(2,898)							(2,898)
Actuarial loss, net of tax					26							26
Net income (loss)						(9,570)						(9,570)
Other						(10)						(10)
Ending Balance at Jun. 30, 2022			$ 885	1,990,281	(38,493)	1,676,069			(200,956)			3,427,786
Ending Balance (in shares) at Jun. 30, 2022			88,451,223
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									75,020,256
Increase (Decrease) in Stockholders' Equity
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes			$ 2	(3,074)								$ (3,072)
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)			219,424
Share repurchases							$ (501,637)	$ (174,322)		$ (501,637)	$ (174,322)
Share repurchases (in shares)	(10,072,055)	(3,972,634)
Retirement of treasury shares			$ (140)	(675,819)					675,959
Stock-based compensation				10,091								10,091
Net investment hedge currency translation adjustment, net of tax					(70,478)							(70,478)
Foreign currency translation adjustments					113,140							113,140
Changes in unrealized gains (losses) on marketable securities, net of tax					4,109							4,109
Net income (loss)						(17,632)						(17,632)
Other						(85)						(85)
Ending Balance at Jun. 30, 2023			$ 747	1,323,215	(37,145)	1,637,639			(200,956)			$ 2,723,500
Ending Balance (in shares) at Jun. 30, 2023			74,656,860									61,194,991
Beginning Balance at Mar. 31, 2023			$ 826	1,495,118	(38,870)	1,639,109			(200,956)			$ 2,895,227
Beginning Balance (in shares) at Mar. 31, 2023			82,602,702
Increase (Decrease) in Stockholders' Equity
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes			$ 0	(18)								(18)
Shares issued under restricted stock and purchase plans, net of shares withheld for employee taxes (in shares)			8,713
Share repurchases							$ (1,637)	$ (174,322)		$ (1,637)	$ (174,322)
Share repurchases (in shares)	(3,981,921)	(3,972,634)
Retirement of treasury shares			$ (80)	(175,880)					175,959
Stock-based compensation				3,995								3,995
Net investment hedge currency translation adjustment, net of tax					(218)							(218)
Foreign currency translation adjustments					1,876							1,876
Changes in unrealized gains (losses) on marketable securities, net of tax					67							67
Net income (loss)						(1,470)						(1,470)
Ending Balance at Jun. 30, 2023			$ 747	$ 1,323,215	$ (37,145)	$ 1,637,639			$ (200,956)			$ 2,723,500
Ending Balance (in shares) at Jun. 30, 2023			74,656,860									61,194,991