Graham Corporation Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets - Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Schedule Of Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross Carrying Amount	$ 2,870	$ 2,870
Finite-Lived Intangible Assets, Accumulated Amortization	852	762
Finite-Lived Intangible Assets, Net Carrying Amount	2,018	2,108
Indefinite Lived Intangible Assets, Net Carrying Amount	12,800	12,800
Backlog [Member]
Schedule Of Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross Carrying Amount	170	170
Finite-Lived Intangible Assets, Accumulated Amortization	170	170
Finite-Lived Intangible Assets, Net Carrying Amount	0	0
Customer Relationships [Member]
Schedule Of Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross Carrying Amount	2,700	2,700
Finite-Lived Intangible Assets, Accumulated Amortization	682	592
Finite-Lived Intangible Assets, Net Carrying Amount	2,018	2,108
Permits [Member]
Schedule Of Intangible Assets [Line Items]
Indefinite Lived Intangible Assets, Net Carrying Amount	10,300	10,300
Tradename [Member]
Schedule Of Intangible Assets [Line Items]
Indefinite Lived Intangible Assets, Net Carrying Amount	$ 2,500	$ 2,500