Annual report pursuant to Section 13 and 15(d)

Organization and Summary of Significant Accounting Policies (Details)

v3.8.0.1
Organization and Summary of Significant Accounting Policies (Details)
 12 Months Ended
Apr. 30, 2010
USD ($)
Mar. 31, 2018
USD ($)
Mar. 31, 2017
USD ($)
Mar. 31, 2016
USD ($)
Business Acquisition [Line Items]        
Accounts receivable, allowance for doubtful accounts (in dollars)   $ 1,231,000 $ 518,000  
Decrease in prepaid expenses and other current assets   (9,054,000) (5,806,000)  
Increase in income tax receivable   1,885,000 2,028,000  
Selling, General and Administrative Expense   94,615,000 77,715,000 $ 80,729,000
Goodwill impaired   0 (1,240,000) 0
Asset Impairment Charges     473,000  
Cost of selling controlling interest $ 129,252,000      
Non-U.S.   $ 33,501,000 $ 21,698,000 $ 19,304,000
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries   68.00% 59.00%  
Entity Wide Disclosure On Geographic Areas, Revenue From External Customers Attributed To Foreign Countries, Percentage   63.00% 55.00% 55.00%
Movement in Valuation Allowances and Reserves [Roll Forward]        
Amortization of Deferred Charges   $ 1,657,000 $ 391,000 $ 732,000
Research and Development Expense   $ 5,240,000 3,501,000 3,338,000
Group of investors and other private equity firms [Member]        
Business Acquisition [Line Items]        
Number of other private equity firms 2      
Land Improvements [Member] | Minimum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   15 years    
Land Improvements [Member] | Maximum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   20 years    
Building and Building Improvements [Member] | Minimum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   10 years    
Building and Building Improvements [Member] | Maximum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   40 years    
Machinery and equipment [Member] | Minimum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   3 years    
Machinery and equipment [Member] | Maximum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   25 years    
Furniture and Fixtures [Member] | Minimum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   3 years    
Furniture and Fixtures [Member] | Maximum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   10 years    
Software Development [Member] | Minimum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   5 years    
Software Development [Member] | Maximum [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Property, plant and equipment, estimated useful lives   7 years    
Allowance for Doubtful Accounts [Member]        
Movement in Valuation Allowances and Reserves [Roll Forward]        
Balance, beginning of period   $ 518,000 656,000 785,000
Reductions to expense   787,000    
Allowance acquired      
Additions charged to expense     307,000 214,000
Write-off of uncollectible accounts   (74,000) (445,000) (343,000)
Balance, end of period   1,231,000 518,000 $ 656,000
Predecessor [Member] | Group of investors and other private equity firms [Member] | Thermon Holding Corp. [Member]        
Business Acquisition [Line Items]        
Fair value of total consideration transferred $ 321,500,000      
Consideration transferred, liabilities incurred $ 210,000,000      
Restatement Adjustment [Member]        
Business Acquisition [Line Items]        
Decrease in prepaid expenses and other current assets     2,000,000  
Increase in income tax receivable   $ 2,000,000    
Correction of Marketing, General and Administrative and Engineering Expense        
Business Acquisition [Line Items]        
Selling, General and Administrative Expense     498,000  
Accounting Standards Update 2015-07        
Business Acquisition [Line Items]        
Increase (Decrease) in Other Noncurrent Assets     $ 1,061,000  
Customer Concentration Risk        
Business Acquisition [Line Items]        
Concentration risk, percentage   4.00% 14.00%  
Term Loan A [Member]        
Business Acquisition [Line Items]        
Accelerated amortization of debt issuance costs   $ 376    
Term Loan B [Member]        
Business Acquisition [Line Items]        
Accelerated amortization of debt issuance costs   880    
Repayments of debt   $ 25,000