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