Annual report pursuant to Section 13 and 15(d)

Organization and Summary of Significant Accounting Policies (Details)

v3.20.1
Organization and Summary of Significant Accounting Policies (Details)
 12 Months Ended
Apr. 30, 2010
USD ($)
Mar. 31, 2020
USD ($)
segment
Geographic_Region
Mar. 31, 2019
USD ($)
Mar. 31, 2018
USD ($)
Business Acquisition [Line Items]        
Number of reportable segments | segment   4    
Accounts receivable, allowance for doubtful accounts (in dollars)   $ 834,000 $ 987,000  
Goodwill impaired   $ 0 $ 0  
Cost of selling controlling interest $ 129,252,000      
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries   61.00% 65.00%  
Entity Wide Disclosure On Geographic Areas, Revenue From External Customers Attributed To Foreign Countries, Percentage   59.00% 63.00% 55.00%
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Amortization of Deferred Charges   $ 1,885,000 $ 1,756,000 $ 1,657,000
Research and Development Expense   $ 8,378,000 6,289,000 5,240,000
Number of Countries in which Entity Operates | Geographic_Region   4    
Group of investors and other private equity firms        
Business Acquisition [Line Items]        
Number of other private equity firms 2      
Group of investors and other private equity firms | Thermon Holding Corp.        
Business Acquisition [Line Items]        
Fair value of total consideration transferred $ 321,500,000      
Consideration transferred, liabilities incurred $ 210,000,000      
Land improvements | Minimum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   15 years    
Land improvements | Maximum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   20 years    
Buildings and improvements | Minimum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   10 years    
Buildings and improvements | Maximum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   40 years    
Machinery and equipment | Minimum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   3 years    
Machinery and equipment | Maximum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   25 years    
Office furniture and equipment | Minimum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   3 years    
Office furniture and equipment | Maximum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   10 years    
Internally developed software | Minimum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   5 years    
Internally developed software | Maximum        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   7 years    
Allowance for Doubtful Accounts        
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]        
Balance, beginning of period   $ 987,000 1,231,000 518,000
Reductions to expense   674,000    
Additions charged to expense     354,000 787,000
Write-off of uncollectible accounts   (827,000) (598,000) (74,000)
Balance, end of period   $ 834,000 $ 987,000 $ 1,231,000