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Employee Benefit Plans - Weighted Average Actuarial Assumptions Used to Develop Projected Benefit Obligation (Detail) (Other Postretirement Benefit Plans [Member])
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Mar. 31, 2015
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Mar. 31, 2014
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Other Postretirement Benefit Plans [Member]
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| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate |
3.11%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember |
3.59%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember |
| Medical care cost trend rate |
8.00%ghm_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationMedicalCareCostTrendRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember |
8.00%ghm_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationMedicalCareCostTrendRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember |
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- Definition
Expected rate used to calculate the benefit obligation medical care cost trend rate. No definition available.
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- Definition
The interest rate used to adjust for the time value of money for the plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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