Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Details)

v3.20.4
Long-Term Debt (Details)
$ in Thousands
 9 Months Ended
Dec. 31, 2020
USD ($)
Jun. 18, 2020
USD ($)
Oct. 30, 2017
USD ($)
Oct. 30, 2017
CAD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Mar. 31, 2020
USD ($)
Apr. 01, 2018
Mar. 31, 2017
USD ($)
Debt Instrument [Line Items]                  
Less current portion $ (2,500,000)       $ (2,500,000)   $ (2,500,000)    
Long-term debt, net of current maturities and deferred debt issuance costs and debt discounts of $3,719 and $4,447 as of December 31, 2020 and March 31, 2020, respectively 162,906,000       162,906,000   169,053,000    
Debt issuance costs, net 3,719,000       3,719,000   4,447,000    
Repayments of long-term debt         44,339,000 $ 46,279,000      
Maximum leverage ratio to secure additional borrowing     4.0 4.0          
Amount of excess cash   $ 20,000              
Loans Payable                  
Debt Instrument [Line Items]                  
Debt Instrument, face amount                 $ 5,905,000
Revolving credit facility                  
Debt Instrument [Line Items]                  
Capacity available under credit facility $ 56,147,000       56,147,000        
Through March 31, 2019 | Loans Payable                  
Debt Instrument [Line Items]                  
Repayments of notes payable         $ 625        
Revolving credit facility | Line of Credit                  
Debt Instrument [Line Items]                  
Debt Instrument, face amount     $ 60,000,000            
Long-term Debt, Term     5 years            
Repayments of lines of credit     $ 6,000,000            
Liabilities incurred       $ 201,900          
Line of credit facility, commitment fee percentage     0.50% 0.50%          
Maximum leverage ratio 3.75                
Debt covenant, coverage ratio     1.25 1.25          
Revolving credit facility | Base Rate | Line of Credit                  
Debt Instrument [Line Items]                  
Basis spread on variable rate     2.25% 2.25%          
Revolving credit facility | London Interbank Offered Rate (LIBOR) | Line of Credit                  
Debt Instrument [Line Items]                  
Basis spread on variable rate     3.25% 3.25%          
Revolving credit facility | Canadian Base Rate [Member] | Line of Credit                  
Debt Instrument [Line Items]                  
Basis spread on variable rate     2.25% 2.25%          
Revolving credit facility | CDOR | Line of Credit                  
Debt Instrument [Line Items]                  
Basis spread on variable rate     3.25% 3.25%          
Variable Rate Term Loan due October 2024                  
Debt Instrument [Line Items]                  
Variable term loan, interest rate 4.75%       4.75%        
Variable Rate Term Loan due October 2024 | Loans Payable                  
Debt Instrument [Line Items]                  
Variable Rate Term Loans $ 165,406,000       $ 165,406,000   171,553,000    
Debt issuance costs, net $ 3,719,000       $ 3,719,000   $ 4,447,000    
Variable Rate Senior Secured Term Loan B | Secured Debt                  
Debt Instrument [Line Items]                  
Debt Instrument, face amount     $ 250,000,000            
Long-term Debt, Term     7 years            
Variable interest rate floor     1.00%            
Quarterly amortization of debt, percent               0.25%  
Repayment requirement, percentage of excess cash flow         50.00%        
Reduced repayment requirement, percentage of excess cash flow         25.00%        
Maximum leverage ratio requirement for reduced payment         4.0        
Minimum leverage ratio requirement for reduced payment         3.5        
Minimum repayment requirement percentage of excess cash flow         0.00%        
Maximum leverage ratio requirement for minimum repayment         3.5        
Maximum leverage ratio         3.5        
Additional borrowing capacity     $ 30,000,000            
Variable Rate Senior Secured Term Loan B | Secured Debt | Subsidiary Stock                  
Debt Instrument [Line Items]                  
Guarantor obligations, percentage     100.00% 100.00%          
Variable Rate Senior Secured Term Loan B | Secured Debt | Stock of First Tier Material Foreign Subsidiaries, US Borrower, and US Subsidiary                  
Debt Instrument [Line Items]                  
Guarantor obligations, percentage     65.00% 65.00%          
Variable Rate Senior Secured Term Loan B | Base Rate | Secured Debt                  
Debt Instrument [Line Items]                  
Basis spread on variable rate     2.75% 2.75%          
Variable Rate Senior Secured Term Loan B | London Interbank Offered Rate (LIBOR) | Secured Debt                  
Debt Instrument [Line Items]                  
Basis spread on variable rate     3.75% 3.75%          
Term Loan A due April 2019                  
Debt Instrument [Line Items]                  
Repayments of long-term debt     $ 70,875,000            
Thermon Heating Systems Inc.                  
Debt Instrument [Line Items]                  
Debt proceeds used as consideration for business acquisition     $ 164,900,000