Consolidated Statements of Stockholder's Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Sep. 30, 2020	$ 1,438,248	$ 1,161	$ 1,602,728	$ (62,267)	$ (103,374)
Beginning balance (in shares) at Sep. 30, 2020		116,125
Common stock issued for employee stock-based awards		$ 8	(8)
Common stock issued for employee stock-based awards (in shares)		802
Shares surrendered by employees to pay taxes related to stock-based awards	(25,431)	$ (2)	(25,429)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(263)
Compensation expense from stock-based awards	46,088		46,088
Net income	23,515			23,515
Unrealized gain (loss) on net investment hedges, net of tax	(6,779)				(6,779)
Foreign currency translation adjustment	19,975				19,975
Unrealized loss on marketable securities, net of tax	(307)				(307)
Change in pension benefits, net of tax	(380)				(380)
Ending balance at Dec. 31, 2020	1,494,929	$ 1,167	1,623,379	(38,752)	(90,865)
Ending balance (in shares) at Dec. 31, 2020		116,664
Beginning balance at Sep. 30, 2021	$ 2,038,468	$ 1,172	1,718,504	414,656	(95,864)
Beginning balance (in shares) at Sep. 30, 2021	117,163	117,163
Common stock issued for employee stock-based awards		$ 11	(11)
Common stock issued for employee stock-based awards (in shares)		1,120
Shares surrendered by employees to pay taxes related to stock-based awards	$ (49,165)	$ (4)	(49,161)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(410)
Compensation expense from stock-based awards	45,942		45,942
Repurchases of common stock	$ (124,999)	$ (10)	(124,989)
Repurchases of common stock (in shares)	(1,003)	(1,003)
Net income	$ 46,089			46,089
Unrealized gain (loss) on net investment hedges, net of tax	2,495				2,495
Foreign currency translation adjustment	(5,668)				(5,668)
Unrealized loss on marketable securities, net of tax	0
Change in pension benefits, net of tax	650				650
Ending balance at Dec. 31, 2021	$ 1,953,812	$ 1,169	$ 1,590,285	$ 460,745	$ (98,387)
Ending balance (in shares) at Dec. 31, 2021	116,870	116,870