Equity Incentive Plans - Additional Information (Details) $ / shares in Units, $ in Thousands		12 Months Ended
		Sep. 30, 2023 USD ($) shares $ / shares	Sep. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock Issuable per Restricted Stock Unit | shares		1
Stock-based compensation		$ 206,459	$ 174,863	$ 177,289
Total unrecognized compensation cost		$ 204,400
Weighted average remaining recognition period, in months		17 months
Common stock were available for grant under the 2000 plan | shares		7,300,000
Common stock were reserved for issuance | shares		2,600,000
ESPP maximum contribution percentage		10.00%
ESPP maximum contribution amount by employee		$ 25,000
ESPP purchase price as a % of stock price		85.00%
Vesting term for outstanding awards		1 year
Shares withheld for tax withholding obligation | shares		600,000	600,000	500,000
Payments of withholding taxes in connection with vesting of stock-based awards		$ 82,448	$ 68,991	$ 52,957
Liability classified awards related to stock-based compensation		44,900
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation		$ 6,800	$ 6,400	$ 7,300
Restricted Shares and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per share | $ / shares		$ 130.64	$ 114.31	$ 111.48
TSR Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per share | $ / shares		179.6
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per share | $ / shares	[1]	$ 130.64
Payments of withholding taxes in connection with vesting of stock-based awards		$ 82,800	$ 69,000	$ 53,100

[1] RSUs granted includes 38 shares from prior period rTSR awards that were earned upon achievement of the performance criteria and vested in November 2022 and 61 shares from prior period performance-based awards that were earned upon achievement of the performance criteria and vested in November 2022.