Graham Corporation Quarterly report pursuant to Section 13 or 15(d)

Revenue Recognition - Additional Information (Detail1)	Jun. 30, 2018
Minimum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-07-01
Contract With Customer Assets And Liabilities [Line Items]
Revenue remaining performance obligation percentage	55.00%
Revenue remaining performance obligation, expected timing of satisfaction, period	1 year
Minimum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01
Contract With Customer Assets And Liabilities [Line Items]
Revenue remaining performance obligation percentage	20.00%
Revenue remaining performance obligation, expected timing of satisfaction, period	2 years
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-07-01
Contract With Customer Assets And Liabilities [Line Items]
Revenue remaining performance obligation percentage	60.00%
Revenue remaining performance obligation, expected timing of satisfaction, period	1 year
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01
Contract With Customer Assets And Liabilities [Line Items]
Revenue remaining performance obligation percentage	25.00%
Revenue remaining performance obligation, expected timing of satisfaction, period	2 years