Annual report pursuant to Section 13 and 15(d)

Long-Term Debt - Narrative (Details)

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Long-Term Debt - Narrative (Details)
12 Months Ended
Sep. 29, 2021
USD ($)
Mar. 31, 2024
USD ($)
Mar. 31, 2023
USD ($)
Mar. 31, 2022
USD ($)
Dec. 29, 2023
USD ($)
Sep. 29, 2021
CAD ($)
Debt Instrument [Line Items]            
Amortization of deferred charges   $ 489,000 $ 317,000 $ 596,000    
Loss on extinguishment of debt   $ 0 0 2,569,000    
Line of credit facility, fixed charge coverage ratio   1.25        
Debt issuance costs, net   $ 918,000 $ 429,000      
December 31, 2022 and each fiscal quarter thereafter            
Debt Instrument [Line Items]            
Consolidated leverage ratio   3.50        
Line of Credit            
Debt Instrument [Line Items]            
Basis spread on variable rate 0.625%          
Capacity available under credit facility   $ 92,740,000        
Outstanding letters of credit   $ 7,260,000        
2023 Incremental U.S. Term Loan Facility            
Debt Instrument [Line Items]            
Variable term loan, interest rate   7.18%        
2023 Incremental U.S. Term Loan Facility | Thermon Manufacturing Company and US Subsidiaries (Guarantor)            
Debt Instrument [Line Items]            
Capital stock first lien assets, percentage   100.00%        
Capital stock first tier material foreign subsidiaries, percentage   65.00%        
Credit Agreement            
Debt Instrument [Line Items]            
Debt issuance costs   $ 759,000   1,265,000    
Loss on extinguishment of debt       $ 2,569,000    
Variable Rate Term Loan due October 2024            
Debt Instrument [Line Items]            
Variable term loan, interest rate   7.05%        
U.S. Revolving Credit Facility            
Debt Instrument [Line Items]            
Variable term loan, interest rate   7.06%        
Revolving Credit Facility | Line of Credit            
Debt Instrument [Line Items]            
Line of credit facility, maximum borrowing capacity $ 100,000,000          
Long-term debt, term 5 years         5 years
Line of credit facility, commitment fee percentage 0.25%          
Secured Debt | Line of Credit            
Debt Instrument [Line Items]            
Long-term debt, term 5 years         5 years
Long-term line of credit           $ 76,182,000
Secured Debt | 2023 Incremental U.S. Term Loan Facility | Line of Credit            
Debt Instrument [Line Items]            
Long-term debt, term 5 years         5 years
Long-term line of credit $ 80,000,000          
Line of credit facility, accordion feature, limit increase         $ 100,000,000  
Debt instrument, face amount         $ 100,000,000  
Secured term loan pricing increase         0.375%