XML 19 R70.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Employee Benefit Plans - Summary of Benefit Payments, Which Reflect Future Service, are Expected to be Paid (Detail) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015
--- | ---
Pension Plans, Defined Benefit [Member] |
Defined Benefit Plan Disclosure [Line Items] |
2016 | $ 1,263 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
2017 | 1,370 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
2018 | 1,467 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
2019 | 1,495 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
2020 | 1,635 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
2021-2025 | 9,128 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
Total | 16,358 ghm_DefinedBenefitPlanExpectedFutureBenefitPaymentsAggregate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_PensionPlansDefinedBenefitMember
Other Postretirement Benefit Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
2016 | 92 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2017 | 89 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2018 | 86 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2019 | 82 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2020 | 78 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2021-2025 | 331 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Total | $ 758 ghm_DefinedBenefitPlanExpectedFutureBenefitPaymentsAggregate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember

X
- Definition Aggregate amount of benefits from a defined benefit plan expected to be paid in the ten fiscal years following the latest fiscal year. + References No definition available. + Details
Name: | ghm_DefinedBenefitPlanExpectedFutureBenefitPaymentsAggregate
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of benefits from a defined benefit plan expected to be paid in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |