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

Changes in Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 109,380	$ 116,551	$ 105,908
Other comprehensive income before reclassifications	1,345	(2,405)
Amounts reclassified from accumulated other comprehensive loss	897	785
Total other comprehensive income	2,242	(1,620)	(3,291)
Ending Balance	114,110	109,380	116,551
Pension and Other Postretirement Benefits Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(10,932)	(9,462)
Other comprehensive income before reclassifications	1,596	(2,255)
Amounts reclassified from accumulated other comprehensive loss	897	785
Total other comprehensive income	2,493	(1,470)
Ending Balance	(8,439)	(10,932)	(9,462)
Foreign Currency Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	256	406
Other comprehensive income before reclassifications	(251)	(150)
Total other comprehensive income	(251)	(150)
Ending Balance	5	256	406
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(10,676)	(9,056)	(5,765)
Ending Balance	$ (8,434)	$ (10,676)	$ (9,056)