Annual report pursuant to Section 13 and 15(d)

Employee Benefits - (Details)

v3.8.0.1
Employee Benefits - (Details) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Mar. 31, 2016
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 $ 2,119 $ 1,634 $ 1,684
Incentive compensation paid 6,656 2,324 2,133
Thermon Europe B.V. [Member]      
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Postretirement healthcare obligation, net 2,185 1,611  
Postretirement Health Care Costs      
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Postemployment benefits expense $ 417 $ 289 $ 295