XML 56 R44.htm IDEA: XBRL DOCUMENT
v3.6.0.2

The Company and Its Accounting Policies - Summary of Costs and Estimated Earnings on Contracts (Detail) - USD ($) $ in Thousands | Mar. 31, 2016 | Mar. 31, 2015
--- | --- | ---
Accounting Policies [Abstract] |  |
Costs incurred since inception on contracts in progress | $ 35,893 | $ 64,912
Estimated earnings since inception on contracts in progress | 1,185 | 16,067
Costs and estimated earnings | 37,078 | 80,979
Less billings to date | 38,267 | 69,636
Net under (over) billings | $ (1,189) |
Net under (over) billings |  | $ 11,343

X
- Definition Aggregate amount of billings to customers for contracts in process since the inception of the contracts. + References No definition available. + Details
Name: | ghm_BillingsToDate
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The total amount that has been or will be billed to customers on all contracts in process. + References No definition available. + Details
Name: | ghm_CostAndEstimatedEarningsOnContractInProgress
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Costs incurred on contracts in process since inception of the contracts. + References No definition available. + Details
Name: | ghm_CostOnContractInProgress
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Estimated earnings on contracts in process since inception of the contracts. + References No definition available. + Details
Name: | ghm_EstimatedEarningsOnContractInProgress
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Liability attributable to (i) billings in excess of costs under the percentage of completion contract accounting method representing the difference between contractually invoiced amounts (billings) and revenue recognized based, for example, on costs incurred to estimated total costs at period end or (ii) contractually invoiced amounts (billings) in excess of costs incurred and accumulated under the completed contract accounting method that are expected to be realized within one year or one operating cycle, whichever is longer, from the reporting date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 35 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=51671739&loc=d3e57788-111642 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 35 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=51671739&loc=d3e57807-111642 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 35 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=51671739&loc=d3e57795-111642 + Details
Name: | us-gaap_BillingsInExcessOfCostCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings which is expected to be collected within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 35 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=51671739&loc=d3e57795-111642 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)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 35 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=51671739&loc=d3e57807-111642 + Details
Name: | us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant