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

Stock-Based Compensation Expense - Stock Options Outstanding, Exercisable and Intrinsic Value (Details)

Stock-Based Compensation Expense - Stock Options Outstanding, Exercisable and Intrinsic Value (Details) (Stock Options [Member], USD $)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 1,654,000	$ 10,285,000	$ 18,387,000
Options outstanding (in shares)	465,042.000	558,466.000	1,132,780	2,179,625
$5.20 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (in shares)	326,415
Options outstanding, weighted average contractual life (in years)	5 years 6 months 18 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 5.20
Options outstanding, aggregate intrinsic value	6,159,451
Options vested and exercisable, number exercisable (in shares)	326,415
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	5 years 6 months 18 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	5.20
Options vested and exercisable, aggregate intrinsic value	6,159,451
$9.82 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (in shares)	14,439
Options outstanding, weighted average contractual life (in years)	5 years 10 months 28 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 9.82
Options outstanding, aggregate intrinsic value	205,756
Options vested and exercisable, number exercisable (in shares)	14,439
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	5 years 10 months 28 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	9.82
Options vested and exercisable, aggregate intrinsic value	205,756
$12.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (in shares)	77,224
Options outstanding, weighted average contractual life (in years)	6 years 1 month 13 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 12.00
Options outstanding, aggregate intrinsic value	932,094
Options vested and exercisable, number exercisable (in shares)	34,524
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	6 years 1 month 13 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	12.00
Options vested and exercisable, aggregate intrinsic value	416,705
$21.52 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (in shares)	46,964
Options outstanding, weighted average contractual life (in years)	7 years 4 months 3 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 21.52
Options outstanding, aggregate intrinsic value	119,758
Options vested and exercisable, number exercisable (in shares)	16,215
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 4 months 3 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	21.52
Options vested and exercisable, aggregate intrinsic value	41,348
$5.20 - $21.52 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (in shares)	465,042
Options outstanding, weighted average contractual life (in years)	5 years 9 months 26 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 8.12
Options outstanding, aggregate intrinsic value	7,417,059
Options vested and exercisable, number exercisable (in shares)	391,593
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	5 years 8 months 5 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	6.65
Options vested and exercisable, aggregate intrinsic value	$ 6,823,260