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

Segment Information - Additional Information (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 Segment	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Number of reportable operating segments									1us-gaap_NumberOfReportableSegments
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
SUDAN
Segment Reporting Information [Line Items]
Net sales									0
IRAN
Segment Reporting Information [Line Items]
Net sales									0
CUBA
Segment Reporting Information [Line Items]
Net sales									0
NORTH KOREA
Segment Reporting Information [Line Items]
Net sales									0
SYRIA
Segment Reporting Information [Line Items]
Net sales									$ 0