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Equipment Disclosure [Text Block] 2026 Senior Notes 2026 Senior Notes [Member] 2026 Senior Notes 2023 Inventory Purchase Obligation, To Be Paid, Remainder of Year One Inventory Purchase Obligation, To Be Paid, Remainder of Year One Repurchase Program Share Repurchase Program [Member] Share Repurchase Program [Member] Options outstanding, Aggregate intrinsic value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Repurchase and retirement of common stock (in shares) Stock Repurchased and Retired During Period, Shares Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Accounts receivable—net Increase (Decrease) in Accounts Receivable Title of 12(b) Security Title of 12(b) Security Subsequent Event [Line Items] Subsequent Event [Line Items] Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Net of Forfeitures Debt Instrument [Line Items] Debt Instrument [Line Items] Business Combination and Asset Acquisition [Abstract] Accrued interest payable Interest Payable Less Than 12 Months, Unrealized Losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Operating lease liability Operating Lease, Liability SEGMENT INFORMATION Segment Reporting Disclosure [Text Block] Amortization of investment premiums (discounts) Accretion (Amortization) of Discounts and Premiums, Investments 2025 Finite-Lived Intangible Asset, Expected Amortization, Year Two 12 Months or Greater, Unrealized Losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) Liabilities and Equity [Abstract] Fair Value [Member] Estimate of Fair Value Measurement [Member] Granted (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost Weighted-average shares used to compute net income per share attributable to Fortinet, Inc.: Diluted shares: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Inventory Inventory Inventory, Net Accounts payable Accounts Payable, Current Alaxala AlaxaIA Networks Corporation [Member] AlaxaIA Networks Corporation Other assets Increase (Decrease) in Other Operating Assets Options vested and expected to vest, Aggregate intrinsic value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Entity Filer Category Entity Filer Category Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Basic (in shares) Weighted-average common shares outstanding-basic (in shares) Weighted Average Number of Shares Outstanding, Basic Issuance of common stock in connection with equity incentive plans - net of tax withholding Stock Issued During Period, Value, Equity Incentive Plans, Net of Taxes Withheld Stock Issued During Period, Value, Equity Incentive Plans, Net of Taxes Withheld United States UNITED STATES Threshold period past due Financing Receivable, Threshold Period Past Due Ownership interest percentage Equity Method Investment, Ownership Percentage Total stock-based compensation expense Share-Based Payment Arrangement, Expense COMMITMENTS AND CONTINGENCIES (Note 11) Commitments and Contingencies Security Exchange Name Security Exchange Name Balance - Beginning (in dollars per share) Balance - Ending (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted-Average Useful Life (in Years) Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] General and administrative General and Administrative Expense [Member] Total revenue Revenue from Contract with Customer, Excluding Assessed Tax Matching contribution on employee contributions, Percent Defined Contribution Plan, Employer Matching Contribution, Percent of Match Cover [Abstract] Cover [Abstract] Interest costs capitalized Interest Costs Capitalized Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Level 3 Fair Value, Inputs, Level 3 [Member] INCOME BEFORE INCOME TAXES AND LOSS FROM EQUITY METHOD INVESTMENT Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Goodwill impairment Goodwill, Impairment Loss EQUITY (DEFICIT) Share-Based Payment Arrangement [Text Block] Allowance for credit losses Accounts Receivable, Allowance for Credit Loss Work in process Inventory, Work in Process, Net of Reserves Deferred tax assets Increase (Decrease) in Deferred Income Taxes REVENUE RECOGNITION Revenue from Contract with Customer [Text Block] Segment Reporting [Abstract] Segment Reporting [Abstract] Non-Controlling Interests Noncontrolling Interest [Member] Risk-free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Thereafter Inventory Purchase Obligation, To Be Paid, Thereafter Inventory Purchase Obligation, To Be Paid, Thereafter Technical support and other Technical Support and Other [Member] Technical Support and Other [Member] Taxes paid related to net share settlement of equity awards Payment, Tax Withholding, Share-Based Payment Arrangement COST OF REVENUE: Cost of Goods and Services Sold [Abstract] TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) Liabilities and Equity Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Goodwill [Roll Forward] Goodwill [Roll Forward] Stock repurchase program, unused balance Stock Repurchase Program, Remaining Authorized Repurchase Amount Land Land [Member] Investments, All Other Investments [Abstract] Investments, All Other Investments [Abstract] RSUs and stock options (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Level 2 Fair Value, Inputs, Level 2 [Member] Current Fiscal Year End Date Current Fiscal Year End Date Accrued interest and penalties related to uncertain tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Vesting [Axis] Vesting [Axis] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Diluted (in dollars per share) Diluted (in dollars per share) Earnings Per Share, Diluted OTHER INTANGIBLE ASSETS—NET Intangible Assets, Net (Excluding Goodwill) Share-Based Payment Arrangement, Tranche Two Share-Based Payment Arrangement, Tranche Two [Member] Stock split ratio, Common stock Stockholders' Equity Note, Stock Split, Conversion Ratio Award vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Stock-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Concentration Risk by Type [Axis] Concentration Risk Type [Axis] Total current liabilities Liabilities, Current Customer Concentration Risk Customer Concentration Risk [Member] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions And Allocation of Recognized Period Costs [Table Text Block] Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. Tabular disclosure of the allocation of equity-based compensation costs to a given line item on the balance sheet and income statement for the period. This may include the reporting line for the costs and the amount capitalized and expensed. INCOME TAX LIABILITIES Accrued Income Taxes, Noncurrent Schedule of Available-for-sale Securities [Table] Schedule of Available-for-Sale Securities [Table] Unrecognized tax benefits Unrecognized Tax Benefits Marketable equity securities Equity Securities [Member] Certificates of deposit and term deposits Certificates of Deposit and Term Deposits [Member] Certificates of Deposit and Term Deposits [Member] Schedule of Share-based Compensation, Restricted Stock Units Award Activity Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Unrecognized tax benefits that would favorably affect effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Share Repurchase Program [Axis] Share Repurchase Program [Axis] Remaining performance obligation Revenue, Remaining Performance Obligation, Amount Corporate debt securities Corporate Debt Securities [Member] Money market funds [Member] Money Market Funds, Excluding Commercial Paper [Member] Money Market Funds, Excluding Commercial Paper [Member] Americas Americas [Member] Possible decrease in unrecognized tax benefits Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit Financial Instruments and Fair Value [Abstract] Financial Instruments and Fair Value [Abstract] Financial Instruments and Fair Value [Abstract] Entity Address, Address Line One Entity Address, Address Line One Less: tax provision (benefit) related to items of other comprehensive income or loss Other Comprehensive Income (Loss), Tax Other Proceeds from (Payments for) Other Financing Activities Product and Service [Axis] Product and Service [Axis] Cash equivalents Cash Equivalents, Line Item [Member] Cash Equivalents, Line Item [Member] INTEREST EXPENSE Interest Expense Trade name Trade Names [Member] Net unrealized gain on investments - net of tax OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax INVENTORY Inventory Disclosure [Text Block] Transfers of evaluation units from inventory to property and equipment Transfers of Evaluation Units from Inventory to Property and Equipment Transfers of Evaluation Units from Inventory to Property and Equipment Equity [Abstract] Summary of Outstanding Debt Schedule of Long-Term Debt Instruments [Table Text Block] Subsequent Event [Table] Subsequent Event [Table] Vested (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Entity Tax Identification Number Entity Tax Identification Number Property and Equipment by Geographic Region Long-Lived Assets by Geographic Areas [Table Text Block] Other than temporary impairment charge Equity Method Investment, Other than Temporary Impairment Performance period Share-Based Compensation Arrangement By Share-Based Payment Award, Performance Period Share-Based Compensation Arrangement By Share-Based Payment Award, Performance Period Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] REVENUE: Revenue from Contract with Customer [Abstract] 2023 (the remainder of 2023) Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Other comprehensive income (loss): Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent [Abstract] Shares withheld for taxes Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Long-term investments Long Term Investments, Line Item [Member] Long Term Investments, Line Item [Member] Total Inventory purchase commitments Inventory Purchase Obligation Inventory Purchase Obligation NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Entity Central Index Key Entity Central Index Key Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Fiscal Years: Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Measurement Frequency [Axis] Measurement Frequency [Axis] Latin America Latin America [Member] Weighted-Average Grant Date Fair Value per Share Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Amount withheld for taxes Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Distributor B Distributor B [Member] Distributor B City Area Code City Area Code General and administrative General and Administrative Expense ASSETS Assets [Abstract] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Schedule of Unrealized Loss on Investments Schedule of Unrealized Loss on Investments [Table Text Block] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Maturities of investments Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Less: comprehensive loss attributable to non-controlling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Change in foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Distributor A Distributor A [Member] Distributor A NON-CASH INVESTING AND FINANCING ACTIVITIES: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Stock-based compensation Share-Based Payment Arrangement, Noncash Expense Cash investment in privately held company Payments to Acquire Equity Method Investments Weighted-average fair value per share granted Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Income Tax Benefit from Stock Option Plans Income Tax Benefit from Stock Option Plans [Table Text Block] Income Tax Benefit from Stock Option Plans [Table Text Block] OTHER LIABILITIES Other Liabilities, Noncurrent LOSS FROM EQUITY METHOD INVESTMENT Loss from equity method investments Income (Loss) from Equity Method Investments Non-cancelable remaining contract term (in excess of) Contract Term Remaining, Non-cancelable Contract Term Remaining, Non-cancelable Available-for-sale Securities, Debt Maturities, Fair Value [Abstract] Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Purchases of property and equipment Purchase of property and equipment Payments to Acquire Property, Plant, and Equipment Research and development Research and Development Expense [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] 2024 Finite-Lived Intangible Asset, Expected Amortization, Year One Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Plano, Texas TEXAS Operating lease liabilities arising from obtaining right-of-use assets Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Customer [Domain] Customer [Domain]