Thermon Group Holdings, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Acquisitions - Narrative (Details)

Acquisitions - Narrative (Details) $ in Thousands				3 Months Ended								12 Months Ended
Acquisitions - Narrative (Details) $ in Thousands	Oct. 30, 2017 USD ($)	Oct. 30, 2017 CAD ($)	Apr. 01, 2015 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)
Business Acquisition [Line Items]
Amortization of intangible assets												$ 16,458,000	$ 11,772,000	$ 12,112,000
Amortization period												10 years 7 months 6 days
Goodwill				$ 210,566,000								$ 210,566,000	122,521,000
Revenues												308,609,000	264,130,000	281,928,000
Operating income (loss)				13,553,000	$ 10,210,000	$ 7,417,000	$ 1,558,000	$ 5,280,000	$ 7,299,000	$ 5,675,000	$ 4,190,000	$ 32,738,000	22,444,000	36,761,000
Industrial Process Insulators, Inc.
Business Acquisition [Line Items]
Equity interests acquired															100.00%
Consideration to or on behalf of sellers at close															$ 21,750,000
Amortization period												7 years 2 months 12 days
Amount of purchase price held in escrow				3,026,000								$ 3,026,000
Goodwill				13,249,000								13,249,000
Thermon Heating Systems Inc.
Business Acquisition [Line Items]
Equity interests acquired	100.00%
Payments to acquire business	$ 204,235,000	$ 261,950
Transaction costs				4,093,000								4,093,000
Goodwill	$ 85,156,000
Revenues												41,011,000
Operating income (loss)												$ 7,266,000
Sumac
Business Acquisition [Line Items]
Equity interests acquired			75.00%
Consideration to or on behalf of sellers at close			$ 10,956,000												$ 10,956,000
Payments to acquire business			10,956,000
Amortization period												3 years 7 months 18 days
Goodwill			7,992,000
Transaction costs														134,000
Debt instrument, face amount			5,905,000
Canada
Business Acquisition [Line Items]
Amortization of intangible assets												$ 7,979,000	3,538,000	3,543,000
Operating income (loss)												26,198,000	8,040,000	7,302,000
Canada \| Sumac
Business Acquisition [Line Items]
Debt instrument, face amount													5,905,000
Operating Segments
Business Acquisition [Line Items]
Goodwill acquired												85,156,000
Goodwill				210,566,000				121,510,000				210,566,000	122,521,000	121,510,000
Revenues												308,609,000	264,130,000	281,928,000
Operating Segments \| Canada
Business Acquisition [Line Items]
Goodwill acquired												85,156,000
Goodwill				$ 128,767,000				$ 44,488,000				128,767,000	43,444,000	44,488,000
Revenues												$ 94,427,000	41,721,000	$ 56,925,000
Canada, Dollars \| Minimum [Member] \| Sumac
Business Acquisition [Line Items]
Debt instrument, maturity payment amount			0
Canada, Dollars \| Maximum \| Sumac
Business Acquisition [Line Items]
Debt instrument, maturity payment amount			$ 7,500,000
Service Life
Business Acquisition [Line Items]
Amortization of intangible assets													299
Performance Based Notes
Business Acquisition [Line Items]
Repayments of debt													$ 5,805