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

Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Fair Values of Company's Pension Plan Assets by Asset Category (Detail)

Employee Benefit Plans - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) (Pension Plans, Defined Benefit [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 40,384	$ 38,548	$ 34,627
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40,384	38,548
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	126	122
Cash [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	126	122
U.S. companies, Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,586	20,396
U.S. companies, Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,586	20,396
International companies, Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,854	4,905
International companies, Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,854	4,905
Fixed income, Corporate bond funds, Intermediate-term [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,109	10,507
Fixed income, Corporate bond funds, Intermediate-term [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,109	10,507
Fixed income, Corporate bond funds, Short-term [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,709	2,618
Fixed income, Corporate bond funds, Short-term [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2,709	$ 2,618