Annual report pursuant to Section 13 and 15(d)

Employee Benefits - (Details)

v3.20.1
Employee Benefits - (Details) - USD ($)
 12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Annual vesting percentage 100.00%    
Employer matching contribution, percent 50.00%    
Maximum annual contribution per employee, percent 6.00%    
Employer discretionary contribution, amount $ 2,607,000 $ 2,315,000 $ 2,119,000
Incentive compensation paid 3,104,000 9,885,000 $ 6,656,000
Deferred compensation plan assets 2,849,000 1,557,000  
Deferred Compensation Liability, Classified, Noncurrent 2,886 1,520  
Deferred Compensation Arrangement with Individual, Compensation Expense (387) (21)  
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax 498 50  
Thermon Europe B.V.      
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Net benefit obligation   $ 1,840,000  
Pension Plan | Thermon Europe B.V.      
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Postretirement healthcare obligation, net $ 2,185,000