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v2.4.1.9

Revenue Recognition - Additional Information (Detail) (USD $) | 9 Months Ended |
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Dec. 31, 2014 | Mar. 31, 2014
Revenue Recognition [Line Items] |  |
Company recognizes planned manufacturing process | 28 days |
Direct labor hours worked on contracts | 0 days 575 hours |
Reserve for credit losses related to unbilled revenue | $ 0 ghm_CreditLossRelatedToUnbilledRevenue |
Receivables billed but not paid under retainage provisions in its customer contracts | $ 1,401,000 us-gaap_ContractReceivableRetainage | $ 901,000 us-gaap_ContractReceivableRetainage
Minimum [Member] |  |
Revenue Recognition [Line Items] |  |
Substantial completion of manufacturing process | 95.00%ghm_SubstantialCompletionOfManufacturingProcess / us-gaap_RangeAxis = us-gaap_MinimumMember |

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- Definition Planned manufacturing process used in determining the applicable revenue recognition method. + References No definition available. + Details
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- Definition Reserve recorded against unbilled revenue for credit losses. + References No definition available. + Details
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Balance Type: | credit
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- Definition Equivalent of four weeks of direct labor hours worked on contracts. + References No definition available. + Details
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- Details
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- Definition The percent at which the manufacturing process of a contract must be completed with regard to direct labor hours for the contract to be considered substantially complete. + References No definition available. + Details
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- Definition Amount billed to customers under long-term contracts or programs that have been withheld because of retainage provisions in a contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 910 -SubTopic 310 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6471494&loc=d3e49370-109356 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3(c)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Subparagraph c(1) -Article 5 + Details
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- Details
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