Graham Corporation Annual report [Section 13 and 15(d), not S-K Item 405]

Revenue Recognition - Revenue Disaggregated by Product Line and Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Disaggregation Of Revenue [Line Items]
Net sales	$ 209,896	$ 185,533	$ 157,118
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	16,884	15,144	16,040
Canada [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,586	4,229	4,464
Middle East [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,088	2,568	2,914
South America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,165	733	3,021
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	169,943	155,908	127,519
All Other [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,230	6,951	3,160
Defense [Member]
Disaggregation Of Revenue [Line Items]
Net sales	121,925	99,493	65,327
Energy & Process [Member]
Disaggregation Of Revenue [Line Items]
Net sales	73,287	72,758	70,611
Space [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 14,684	$ 13,282	$ 21,180