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, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Disaggregation Of Revenue [Line Items]
Net sales	$ 69,760	$ 66,027	$ 141,102	$ 121,514
Defense [Member]
Disaggregation Of Revenue [Line Items]
Net sales	45,827	40,750	87,210	70,285
Space [Member]
Disaggregation Of Revenue [Line Items]
Net sales	6,373	3,999	12,660	7,377
Energy and Process [Member]
Disaggregation Of Revenue [Line Items]
Net sales	17,560	21,278	41,232	43,852
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	431	4,452	1,896	7,735
Canada [Member]
Disaggregation Of Revenue [Line Items]
Net sales	853	3,617	1,585	7,127
Middle East [Member]
Disaggregation Of Revenue [Line Items]
Net sales	2,239	1,770	5,667	3,116
South America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	332	58	636	451
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	64,811	55,098	129,274	101,420
All Other [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 1,094	$ 1,032	$ 2,044	$ 1,665