v3.26.3
5. Government Grants (Details) - USD ($)
$ in Thousands
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Dec. 31, 2024
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Government Assistance [Line Items]            
Government Assistance, Award Amount   $ 6,100   $ 6,100    
Government Assistance, Refunds Received       117,600    
December 2024 Agreement            
Government Assistance [Line Items]            
Government Assistance, Gross Amount Prior To Transfer $ 857,200          
Aggregate Transaction Price for Sale of Section 45X Tax Credits 818,600          
Cash Proceeds Received from Sale of Section 45X Tax Credits $ 616,000         $ 202,600
June and July 2025 Agreements            
Government Assistance [Line Items]            
Government Assistance, Gross Amount Prior To Transfer           701,900
Aggregate Transaction Price for Sale of Section 45X Tax Credits           668,100
Cash Proceeds Received from Sale of Section 45X Tax Credits           668,100
October 2025 Agreement            
Government Assistance [Line Items]            
Government Assistance, Gross Amount Prior To Transfer           699,700
Aggregate Transaction Price for Sale of Section 45X Tax Credits           668,200
Cash Proceeds Received from Sale of Section 45X Tax Credits       95,200   $ 573,000
Income Statement Location [Axis]: us-gaap:CostOfGoodsAndServicesSold            
Government Assistance [Line Items]            
Government Grants, Amount, Consolidated Statement of Operations   $ 637,973 $ 396,311 $ 1,500,486 $ 1,075,172  
Government Assistance, Operating Income, Increase (Decrease), Statement of Income or Comprehensive Income [Extensible Enumeration]   Cost of sales Cost of sales Cost of sales Cost of sales  
Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpense            
Government Assistance [Line Items]            
Government Grants, Amount, Consolidated Statement of Operations   $ 281 $ 44 $ 629 $ 2,235  
Government Assistance, Operating Income, Increase (Decrease), Statement of Income or Comprehensive Income [Extensible Enumeration]   Research and development Research and development Research and development Research and development  
Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense            
Government Assistance [Line Items]            
Government Grants, Amount, Consolidated Statement of Operations   $ 7 $ 13 $ 41 $ 61  
Government Assistance, Operating Income, Increase (Decrease), Statement of Income or Comprehensive Income [Extensible Enumeration]   Selling, general and administrative Selling, general and administrative Selling, general and administrative Selling, general and administrative  
Income Statement Location [Axis]: fslr:ProductionStartUpExpense            
Government Assistance [Line Items]            
Government Grants, Amount, Consolidated Statement of Operations   $ 207 $ 0 $ 207 $ 0  
Government Assistance, Operating Income, Increase (Decrease), Statement of Income or Comprehensive Income [Extensible Enumeration]   Production start-up Production start-up Production start-up Production start-up