Graham Corporation Annual report pursuant to Section 13 and 15(d)

Leases - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Capital Leased Assets [Line Items]
Operating leases expense	$ 596us-gaap_OperatingLeasesRentExpenseNet	$ 563us-gaap_OperatingLeasesRentExpenseNet	$ 513us-gaap_OperatingLeasesRentExpenseNet
Machinery and Equipment [Member]
Capital Leased Assets [Line Items]
Amortization of machinery and equipment under capital leases	$ 54	$ 72	$ 84