v3.26.1
Commitments and Contingencies - Narrative (Details) - USD ($)
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2026
Dec. 31, 2025
Loss Contingencies [Line Items]      
Inventory purchase commitments $ 1,667,100,000 $ 1,667,100,000  
Accrued inventory purchase commitments 24,000,000.0 24,000,000.0 $ 26,700,000
Inventory purchase (benefit) expense 0 0  
Other contractual commitments and open purchase orders 110,900,000 $ 110,900,000  
Non-cancelable remaining contract term (in excess of)   1 year  
Operating lease liability 64,500,000 $ 64,500,000  
Oklahoma Firefighters Pension and Retirement System v. Fortinet, Inc., et al And State Of Rhode Island Office Of The General Treasurer V. Fortinet, Inc. et al      
Loss Contingencies [Line Items]      
Loss accrual 0 0  
Alorica v. Fortinet      
Loss Contingencies [Line Items]      
Loss accrual $ 0 $ 0 $ 0