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Stock-Based Compensation - Narrative (Details) - USD ($) |  | 12 Months Ended
--- | --- | ---
Oct. 31, 2024 | Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Payment Arrangement, Expense |  | $ 219,100,000 | $ 236,700,000 | $ 249,200,000
Share-based Payment Arrangement, Expense, Tax Benefit |  | 44,400,000 | $ 44,700,000 | $ 47,300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount |  | $ 171,200,000 |  |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition |  | 2 years |  |
Expected term |  | 6 months | 6 months | 6 months
Weighted Average Grant Date Fair Value |  | $ 155.99 | $ 144.78 | $ 206.13
Fair market value of restricted stock vested |  | $ 228,100,000 | $ 195,900,000 | $ 262,400,000
Total intrinsic value of options exercised |  | $ 7,500,000 | $ 6,900,000 | $ 25,600,000
Subsequent Event [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Equity Instruments Other than Options, Grants in Period | 748,580 |  |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Award vesting period |  | 2 years | 2 years | 2 years
Two Thousand Eleven Employee Stock Purchase Plan [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Common stock reserved for issuance |  | 12,000,000 |  |
Percentage of base compensation for which employees can acquire shares of common stock |  | 15.00% |  |
Maximum shares allowed for purchase by employee in period |  | 10,000 |  |
Maximum aggregate fair value of stock that an employee may purchase |  | $ 25,000 |  |
Expected term |  | 6 months |  |
Percentage of common stock lesser of the fair market value |  | 85.00% |  |
Number of Shares Authorized |  | 2,007,597 |  |
Two Thousand Fourteen Equity Incentive Plan [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Common stock reserved for issuance |  | 27,880,000 |  |
Number of Shares Authorized |  | 3,952,900 |  |
Vesting rate of stock options and awards upon certain changes in ownership control |  | 50.00% |  |
Two Thousand Fourteen Equity Incentive Plan [Member] | Performance Shares [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Equity Instruments Other than Options, Grants in Period |  | 122,841 |  |
Outstanding stock units |  | 213,776 | 199,918 |
Shares Issued in Period |  | 122,841 |  |
Weighted Average Grant Date Fair Value |  | $ 155.63 | $ 159.37 |
Two Thousand Fourteen Equity Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Equity Instruments Other than Options, Grants in Period |  | 1,459,527 |  |
Outstanding stock units |  | 1,312,328 | 1,225,386 |
Shares Issued in Period |  | 1,459,527 |  |
Weighted Average Grant Date Fair Value |  | $ 158.22 | $ 156.89 |
Nginx Acquisition Equity Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Outstanding stock units |  | 19 |  |
Volterra Acquisition Equity Incentive Plan | Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Outstanding stock units |  | 4,679 |  |
Threat Stack Acquisition Equity Incentive Plan | Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Outstanding stock units |  | 2,351 |  |
Lilac Acquisition Equity Incentive Plan | Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Outstanding stock units |  | 20,601 |  |
Lilac Cloud 2018 Equity Incentive Plan | Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Outstanding stock units |  | 1,059 |  |
Lilac Cloud 2018 Equity Incentive Plan | Share-based Payment Arrangement, Option [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Shares available for purchase under stock option plan |  | 947 |  |
Nginx, Inc. 2011 Share Plan [Member] | Share-based Payment Arrangement, Option [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Shares available for purchase under stock option plan |  | 3,374 |  |
Shape 2011 Share Plan [Member] | Share-based Payment Arrangement, Option [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Shares available for purchase under stock option plan |  | 31,363 |  |
Volterra 2017 Stock Plan | Share-based Payment Arrangement, Option [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Shares available for purchase under stock option plan |  | 18,406 |  |

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