v3.26.3
Acquisitions - Additional Information (Detail)
$ / shares in Units, $ in Thousands, € in Millions
 3 Months Ended 4 Months Ended 9 Months Ended
Jun. 01, 2026
USD ($)
$ / shares
shares
Feb. 13, 2026
USD ($)
Jan. 03, 2025
USD ($)
Sep. 30, 2026
USD ($)
Jun. 30, 2026
USD ($)
Mar. 31, 2026
USD ($)
Sep. 30, 2025
USD ($)
Jun. 30, 2025
USD ($)
Mar. 31, 2025
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2026
EUR (€)
Sep. 30, 2025
USD ($)
May 29, 2026
$ / shares
Business Acquisition Contingent Consideration [Line Items]                            
Repayment of Thermon indebtedness $ 141,682                          
Acquisition and integration expense       $ 12,430     $ 252       $ 68,172   $ 8,427  
Increase to Goodwill       4,000                    
Net (loss) income       (1,912) $ (34,489) $ (248) 1,807 $ 10,105 $ 36,442   (36,648)   48,356  
Net (loss) income attributable to CECO Environmental Corp.       (2,018)     $ 1,499       (37,184)   $ 46,993  
Revenues | €                       € 750    
Land, Building and Improvements                            
Business Acquisition Contingent Consideration [Line Items]                            
Property and equipment       14,700           $ 14,700 14,700      
Vehicles                            
Business Acquisition Contingent Consideration [Line Items]                            
Property and equipment       2,100           2,100 2,100      
Other Machinery and Equipment                            
Business Acquisition Contingent Consideration [Line Items]                            
Property and equipment       600           600 600      
Thermon Group Holdings, Inc.                            
Business Acquisition Contingent Consideration [Line Items]                            
Consideration received per share | $ / shares $ 79.03                         $ 61.14
Consideration Received (Per Share) | $ / shares $ 63.89                          
Shares Converted | shares 0.811                          
Per share cash and stock consideration | $ / shares $ 64                          
Acquisition of equity                           4.70%
Fair values of the assets acquired and liabilities assumed and allocated to goodwill $ 1,214,500                          
Acquisition Related Costs       0             34,300      
Fair value                     26,200      
Property and equipment $ 129,785                          
Net (loss) income                     14,300      
Net (loss) income attributable to CECO Environmental Corp.       (28,600)           (33,900)        
Revenues       148,500           198,100        
Transaction costs                     34,300      
Thermon Group Holdings, Inc. | Technology                            
Business Acquisition Contingent Consideration [Line Items]                            
Intangible assets, Useful Life 20 years                          
Thermon Group Holdings, Inc. | Customer lists | Minimum                            
Business Acquisition Contingent Consideration [Line Items]                            
Intangible assets, Useful Life 20 years                          
Thermon Group Holdings, Inc. | Customer lists | Maximum                            
Business Acquisition Contingent Consideration [Line Items]                            
Intangible assets, Useful Life 25 years                          
Thermon Group Holdings, Inc. | Tradenames                            
Business Acquisition Contingent Consideration [Line Items]                            
Intangible assets, Useful Life 20 years                          
Thermon Group Holdings, Inc. | Backlog                            
Business Acquisition Contingent Consideration [Line Items]                            
Intangible assets, Useful Life 3 years                          
Thermon Group Holdings, Inc. | Common Stock                            
Business Acquisition Contingent Consideration [Line Items]                            
Consideration received per share | $ / shares $ 10                          
Consideration Received (Per Share) | $ / shares $ 0.684                          
Flexible Specialty Products LLC                            
Business Acquisition Contingent Consideration [Line Items]                            
Cash Acquired from Acquisition   $ 6,800                        
Earn out, Fair value   3,300                        
Earnout Payments   4,000                        
Acquired intangible assets   $ 6,100                        
Intangible assets, Useful Life   10 years                        
Net assets acquired   $ 10,050                        
Net (loss) income attributable to CECO Environmental Corp.       100             600      
Revenues       1,200             3,000      
Profire Energy Inc                            
Business Acquisition Contingent Consideration [Line Items]                            
Repayment of Thermon indebtedness     $ 122,700                      
Acquisition and integration expense     2,300                      
Deferred cash consideration     4,600                      
Property and equipment     17,416                      
Net assets acquired     $ 120,382                      
Profire Energy Inc | Technology                            
Business Acquisition Contingent Consideration [Line Items]                            
Acquired intangible assets       $ 3,600           $ 3,600 $ 3,600      
Intangible assets, Useful Life       7 years           7 years 7 years      
Profire Energy Inc | Customer lists                            
Business Acquisition Contingent Consideration [Line Items]                            
Acquired intangible assets       $ 34,500           $ 34,500 $ 34,500      
Intangible assets, Useful Life       10 years           10 years 10 years      
Profire Energy Inc | Tradenames                            
Business Acquisition Contingent Consideration [Line Items]                            
Acquired intangible assets       $ 3,700           $ 3,700 $ 3,700      
Intangible assets, Useful Life       10 years           10 years 10 years