Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2025
Accounting Policies [Abstract]
Description of Business	Description of Business F5, Inc. (the "Company") is a global leader in application delivery and security solutions which enables its customers to deploy, operate, secure, optimize, and govern every application and API across any architecture - on-premises, in the cloud, or at the edge. The Company's cloud, software, and hardware solutions enable its customers to deliver fast, available, and secure digital experiences to their customers at scale. The Company's enterprise-grade application services are available as hardware, software, and software-as-a-service solutions optimized for hybrid, multicloud environments, with modules that can run independently, or as part of an integrated solution on its high-performance appliances. In connection with its solutions, the Company offers a broad range of professional services, including consulting, training, maintenance, and other technical support services.
Basis of Presentation	Basis of Presentation The year-end consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America ("GAAP"). In the opinion of management, the unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, necessary for their fair statement in conformity with accounting principles generally accepted in the United States of America. Certain information and footnote disclosures normally included in annual financial statements have been condensed or omitted in accordance with the rules and regulations of the Securities and Exchange Commission ("SEC"). The information included in this Form 10-Q should be read in conjunction with Management’s Discussion and Analysis of Financial Condition and Results of Operations and financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2024.
Recent Accounting Pronouncements	There have been no changes to the Company's significant accounting policies as of and for the three and nine months ended June 30, 2025, except for the accounting policies for investments and fair value of financial instruments, which have been updated to include equity investments with no readily determinable fair value. Investments The Company classifies its debt investments as available-for-sale. Debt investments, consisting of money market funds, corporate and municipal bonds and notes, and the United States government and agency securities, are reported at fair value with the related unrealized gains and losses included as a component of accumulated other comprehensive income (loss) in shareholders’ equity. Realized gains and losses, credit allowances and impairments due to credit losses are included in other income (expense) in the Company’s consolidated income statements. Debt investments with maturities of less than one year or where management’s intent is to use the investments to fund current operations are classified as short-term investments. Debt investments with maturities of greater than one year are classified as long-term investments. Equity investments without readily determinable fair values are measured at cost with adjustments for observable changes in price or impairments, or measured using net asset value as a practical expedient to fair value and are classified as long-term investments on the Company's consolidated balance sheets. The Company performs a qualitative assessment on a periodic basis and recognizes an impairment if there are sufficient indicators that the fair value of the investment is less than carrying value. Changes in value are recorded in other income (expense) in the Company's consolidated income statements. Fair Value of Financial Instruments Short-term and long-term debt investments are recorded at fair value as the underlying securities are classified as available-for-sale with any unrealized gains or losses being recorded to other comprehensive income (loss). The fair value for securities held is determined using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. New Accounting Pronouncements In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ("ASU 2023-07"). This ASU expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact of this standard on its disclosures in the consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures ("ASU 2023-09"). This ASU requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact of this standard on its disclosures in the consolidated financial statements. In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses ("ASU 2024-03"). This ASU requires new financial statement disclosures disaggregating prescribed expense categories within relevant income statement expense captions. In addition, in January 2025, the FASB issued ASU No. 2025-01, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date, which clarifies the effective date of ASU 2024-03. ASU 2024-03 will be effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of this standard on its disclosures in the consolidated financial statements.