CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Treasury Stock	Total
Beginning Balance at Sep. 30, 2020	$ 873	$ 1,942,850	$ 21,919	$ (551,072)	$ (200,956)	$ 1,213,614
Beginning Balance (in shares) at Sep. 30, 2020	87,293,710
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under restricted stock and purchase plans, net	$ 5	2,578				2,583
Shares issued under restricted stock and purchase plans, net (in shares)	464,888
Stock-based compensation		20,277				20,277
Common stock dividends declared				(22,287)		(22,287)
Foreign currency translation adjustments			4,720			4,721
Actuarial loss, net of tax effects			(20)			(20)
Net (loss) income				88,942		88,942
Ending Balance at Jun. 30, 2021	$ 878	1,965,705	26,619	(484,417)	(200,956)	1,307,829
Ending Balance (in shares) at Jun. 30, 2021	87,758,598
Beginning Balance at Mar. 31, 2021	$ 878	1,959,619	22,637	(516,152)	(200,956)	1,266,026
Beginning Balance (in shares) at Mar. 31, 2021	87,755,666
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under restricted stock and purchase plans, net (in shares)	2,932
Stock-based compensation		6,086				6,086
Common stock dividends declared				(7,431)		(7,431)
Foreign currency translation adjustments			4,003			4,003
Actuarial loss, net of tax effects			(21)			(21)
Net (loss) income				39,166		39,166
Ending Balance at Jun. 30, 2021	$ 878	1,965,705	26,619	(484,417)	(200,956)	1,307,829
Ending Balance (in shares) at Jun. 30, 2021	87,758,598
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					74,347,053
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under restricted stock and purchase plans, net	$ 7	3,454				$ 3,461
Shares issued under restricted stock and purchase plans, net (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 effects of $13,815 and $16,733, respectively, for the three and nine months ended June 30, 2022			49,081			49,081
Foreign currency translation reclassification adjustments included in income from discontinued operation (Note 2)			(16,567)			(16,567)
Foreign currency translation adjustments			(85,160)			(85,160)
Changes in unrealized gains on marketable securities, net of tax			(5,306)			(5,306)
Actuarial loss, net of tax effects			108			108
Net (loss) income				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					74,989,354
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 [Roll Forward]
Shares issued under restricted stock and purchase plans, net (in shares)	1,140
Stock-based compensation		3,485				3,485
Net investment hedge currency translation adjustment, net of tax effects of $13,815 and $16,733, respectively, for the three and nine months ended June 30, 2022			41,956			41,956
Foreign currency translation adjustments			(70,179)			(70,179)
Changes in unrealized gains on marketable securities, net of tax			(2,898)			(2,898)
Actuarial loss, net of tax effects			26			26
Net (loss) income				(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					74,989,354