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

Segment Information - Net Sales by Product Line (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Net sales	$ 37,455us-gaap_SalesRevenueNet	$ 33,646us-gaap_SalesRevenueNet	$ 35,566us-gaap_SalesRevenueNet	$ 28,502us-gaap_SalesRevenueNet	$ 26,087us-gaap_SalesRevenueNet	$ 23,385us-gaap_SalesRevenueNet	$ 24,490us-gaap_SalesRevenueNet	$ 28,256us-gaap_SalesRevenueNet	$ 135,169us-gaap_SalesRevenueNet	$ 102,218us-gaap_SalesRevenueNet	$ 104,973us-gaap_SalesRevenueNet
Heat transfer equipment [Member]
Segment Reporting Information [Line Items]
Net sales									58,224	37,086	43,764
Vacuum equipment [Member]
Segment Reporting Information [Line Items]
Net sales									28,698	27,236	22,891
All other [Member]
Segment Reporting Information [Line Items]
Net sales									$ 48,247	$ 37,896	$ 38,318