Consolidated Statements of Stockholder's Equity - USD ($) shares in Thousands, $ in Thousands	Total	Net Investment Hedging	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Net Investment Hedging
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			$ 9	(9)
Common stock issued for employee stock-based awards (in shares)			862
Shares surrendered by employees to pay taxes related to stock-based awards	(27,241)		$ (2)	(27,239)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)			(276)
Common stock issued for employee stock purchase plan	10,484		$ 1	10,483
Common stock issued for employee stock purchase plan (in shares)			144
Compensation expense from stock-based awards	90,828			90,828
Net income	132,777				132,777
Unrealized gain (loss) on net investment hedges, net of tax		$ 238					$ 238
Foreign currency translation adjustment	4,124					4,124
Unrealized loss on available-for-sale securities, net of tax	(307)					(307)
Change in pension benefits, net of tax	1,382					1,382
Ending balance at Mar. 31, 2021	1,650,533		$ 1,169	1,676,791	70,510	(97,937)
Ending balance (in shares) at Mar. 31, 2021			116,855
Beginning balance at Dec. 31, 2020	1,494,929		$ 1,167	1,623,379	(38,752)	(90,865)
Beginning balance (in shares) at Dec. 31, 2020			116,664
Common stock issued for employee stock-based awards			$ 1	(1)
Common stock issued for employee stock-based awards (in shares)			60
Shares surrendered by employees to pay taxes related to stock-based awards	(1,810)			(1,810)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)			(13)
Common stock issued for employee stock purchase plan	10,484		$ 1	10,483
Common stock issued for employee stock purchase plan (in shares)			144
Compensation expense from stock-based awards	44,740			44,740
Net income	109,262				109,262
Unrealized gain (loss) on net investment hedges, net of tax		7,017					7,017
Foreign currency translation adjustment	(15,851)					(15,851)
Unrealized loss on available-for-sale securities, net of tax	0
Change in pension benefits, net of tax	1,762					1,762
Ending balance at Mar. 31, 2021	1,650,533		$ 1,169	1,676,791	70,510	(97,937)
Ending balance (in shares) at Mar. 31, 2021			116,855
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			$ 12	(12)
Common stock issued for employee stock-based awards (in shares)			1,171
Shares surrendered by employees to pay taxes related to stock-based awards	$ (50,595)		$ (4)	(50,591)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)			(422)
Common stock issued for employee stock purchase plan	10,857		$ 1	10,856
Common stock issued for employee stock purchase plan (in shares)			110
Compensation expense from stock-based awards	83,863			83,863
Repurchases of common stock	$ (125,000)		$ (11)	(124,989)
Repurchases of common stock (in shares)	1,046		(1,046)
Net income	$ 135,768				135,768
Unrealized gain (loss) on net investment hedges, net of tax		6,192					6,192
Foreign currency translation adjustment	(17,024)					(17,024)
Unrealized loss on available-for-sale securities, net of tax	0
Change in pension benefits, net of tax	1,448					1,448
Ending balance at Mar. 31, 2022	$ 2,083,977		$ 1,170	1,637,631	550,424	(105,248)
Ending balance (in shares) at Mar. 31, 2022	116,976		116,976
Beginning balance at Dec. 31, 2021	$ 1,953,812		$ 1,169	1,590,285	460,745	(98,387)
Beginning balance (in shares) at Dec. 31, 2021			116,870
Common stock issued for employee stock-based awards			$ 1	(1)
Common stock issued for employee stock-based awards (in shares)			51
Shares surrendered by employees to pay taxes related to stock-based awards	(1,430)			(1,430)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)			(12)
Common stock issued for employee stock purchase plan	10,857		$ 1	10,856
Common stock issued for employee stock purchase plan (in shares)			110
Compensation expense from stock-based awards	37,921			37,921
Repurchases of common stock	$ (1)		$ (1)
Repurchases of common stock (in shares)	43		(43)
Net income	$ 89,679				89,679
Unrealized gain (loss) on net investment hedges, net of tax		$ 3,697					$ 3,697
Foreign currency translation adjustment	(11,356)					(11,356)
Unrealized loss on available-for-sale securities, net of tax	0
Change in pension benefits, net of tax	798					798
Ending balance at Mar. 31, 2022	$ 2,083,977		$ 1,170	$ 1,637,631	$ 550,424	$ (105,248)
Ending balance (in shares) at Mar. 31, 2022	116,976		116,976