XML 25 R31.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Intangible Assets - Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Mar. 31, 2014
--- | --- | ---
Schedule Of Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross Carrying Amount | $ 2,870 us-gaap_FiniteLivedIntangibleAssetsGross | $ 2,870 us-gaap_FiniteLivedIntangibleAssetsGross
Finite-Lived Intangible Assets, Accumulated Amortization | 897 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization | 762 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Finite-Lived Intangible Assets, Net Carrying Amount | 1,973 us-gaap_FiniteLivedIntangibleAssetsNet | 2,108 us-gaap_FiniteLivedIntangibleAssetsNet
Indefinite Lived Intangible Assets, Net Carrying Amount | 12,800 us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill | 12,800 us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Backlog [Member] |  |
Schedule Of Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross Carrying Amount | 170 us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember | 170 us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember
Finite-Lived Intangible Assets, Accumulated Amortization | 170 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember | 170 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember
Finite-Lived Intangible Assets, Net Carrying Amount | 0 us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember | 0 us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember
Customer Relationships [Member] |  |
Schedule Of Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross Carrying Amount | 2,700 us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember | 2,700 us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Finite-Lived Intangible Assets, Accumulated Amortization | 727 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember | 592 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Finite-Lived Intangible Assets, Net Carrying Amount | 1,973 us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember | 2,108 us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Permits [Member] |  |
Schedule Of Intangible Assets [Line Items] |  |
Indefinite Lived Intangible Assets, Net Carrying Amount | 10,300 us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = ghm_NuclearPermitsMember | 10,300 us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = ghm_NuclearPermitsMember
Tradename [Member] |  |
Schedule Of Intangible Assets [Line Items] |  |
Indefinite Lived Intangible Assets, Net Carrying Amount | $ 2,500 us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember | $ 2,500 us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember

X
- Details
Name: | ghm_ScheduleOfIntangibleAssetsLineItems
Namespace Prefix: | ghm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OrderOrProductionBacklogMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=ghm_NuclearPermitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |