Graham Corporation Quarterly report [Sections 13 or 15(d)]

Revenue Recognition - Revenue Disaggregated by Product Line and Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation Of Revenue [Line Items]
Net sales	$ 66,027	$ 53,563	$ 121,514	$ 103,514
Defense [Member]
Disaggregation Of Revenue [Line Items]
Net sales	40,750	30,897	70,285	59,991
Energy and Process [Member]
Disaggregation Of Revenue [Line Items]
Net sales	21,278	19,250	43,852	36,160
Space [Member]
Disaggregation Of Revenue [Line Items]
Net sales	3,999	3,416	7,377	7,363
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	4,452	4,274	7,735	9,576
Canada [Member]
Disaggregation Of Revenue [Line Items]
Net sales	3,617	1,665	7,127	2,661
Middle East [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,770	794	3,116	1,777
South America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	58	314	451	369
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	55,098	45,460	101,420	86,390
All Other [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 1,032	$ 1,056	$ 1,665	$ 2,741