Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Details)

v3.19.3
Long-Term Debt (Details)
$ in Thousands
6 Months Ended 9 Months Ended 12 Months Ended
Dec. 31, 2020
Oct. 30, 2017
CAD ($)
Oct. 30, 2017
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Sep. 30, 2020
Sep. 30, 2019
USD ($)
Mar. 31, 2019
USD ($)
Apr. 01, 2018
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 $5,432 and $6,271 as of September 30, 2019 and March 31, 2019, respectively       187,318,000     187,318,000 197,729,000  
Debt issuance costs, net       5,432,000     5,432,000 6,271,000  
Repayments of long-term debt       23,131,000 $ 17,790,000        
Maximum leverage ratio to secure additional borrowing   4.0 4.0            
Outstanding borrowings       9,439,000     9,439,000 11,225,000  
Loans Payable                  
Debt Instrument [Line Items]                  
Debt Instrument, face amount               5,905,000  
Revolving credit facility                  
Debt Instrument [Line Items]                  
Outstanding borrowings       9,439,000     9,439,000 11,225,000  
Capacity available under credit facility       46,803,000     $ 46,803,000    
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            
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             5.0    
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 | Loans Payable                  
Debt Instrument [Line Items]                  
Variable Rate Term Loans       189,818,000     $ 189,818,000 200,229,000  
Debt issuance costs, net       $ 5,432,000     $ 5,432,000 $ 6,271,000  
Variable Rate Senior Secured Term Loan B | Secured Debt                  
Debt Instrument [Line Items]                  
Debt Instrument, face amount     $ 250,000,000            
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  
Additional borrowing capacity     $ 30,000,000            
Maximum leverage ratio       3.5          
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            
Scenario, Forecast | Revolving credit facility | Line of Credit                  
Debt Instrument [Line Items]                  
Maximum leverage ratio 3.75         4.5      
Canadian Borrower | Revolving credit facility                  
Debt Instrument [Line Items]                  
Interest rate at period end (as a percent)       4.55%     4.55%