XML 46 R35.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Revenue Recognition - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2018 | Apr. 01, 2018 | Mar. 31, 2018
Contract With Customer Assets And Liabilities [Line Items] |  |  |  |
Percentage of revenue from contracts recognized over time | 50.00% | 40.00% |  |
Percentage of revenue from contracts recognized upon shipment | 50.00% | 60.00% |  |
Revenue recognized included in contract liability | $ 397 | $ 9,323 |  |
Unbilled revenue (contract assets) |  | 1,225 |  |
Contract with customer liability increase in contract asset due to contract progress. |  | 6,503 |  |
Contract with customer liability offset by invoicing to customers. |  | 5,278 |  |
Customer deposits, current |  | 5,987 |  |
Contract with customer liability offset by new customer deposits. | 15,310 | 15,310 |  |
Receivables billed but not paid under retainage provisions in its customer contracts | 2,027 | 2,027 |  | $ 1,124
Amortization expense | 33 | 115 |  |
Revenue remaining unsatisfied performance obligations amount | 133,694 | 133,694 |  |
Customer Deposit [Member] |  |  |  |
Contract With Customer Assets And Liabilities [Line Items] |  |  |  |
Contract liabilities | 4,453 | 4,453 | $ 2,220 |
Prepaid Expenses and Other Current Assets [Member] |  |  |  |
Contract With Customer Assets And Liabilities [Line Items] |  |  |  |
Capitalized costs, net of amortization | $ 126 | $ 126 | $ 118 |

X
- Definition The change in the balance of the contract with customer asset. + References No definition available. + Details
Name: | ghm_ChangeInContractWithCustomerAsset
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The change in the balance of the contract with customer asset. + References No definition available. + Details
Name: | ghm_ChangeInContractWithCustomerLiability
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Contract with customer assets and liabilities. + References No definition available. + Details
Name: | ghm_ContractWithCustomerAssetsAndLiabilitiesLineItems
Namespace Prefix: | ghm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase in contract with customer liability due to consideration that has been received or is receivable. + References No definition available. + Details
Name: | ghm_ContractWithCustomerLiabilityConsiderationReceived
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of obligation to transfer good or service to customer for which consideration is receivable. + References No definition available. + Details
Name: | ghm_ContractWithCustomerLiabilityConsiderationReceiviable
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The percentage of total revenue from contracts from customers from the satisfaction of performance obligations at a point in time. + References No definition available. + Details
Name: | ghm_PercentageOfRevenueFromContractsWithCustomersExcludingAssessedTaxPerformanceObligationSatisfiedAtPointInTime
Namespace Prefix: | ghm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of total revenue from contracts from customers from the satisfaction of performance obligations satisfied over time. + References No definition available. + Details
Name: | ghm_PercentageOfRevenueFromContractsWithCustomersExcludingAssessedTaxPerformanceObligationSatisfiedOverTime
Namespace Prefix: | ghm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 340 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054 + Details
Name: | us-gaap_CapitalizedContractCostAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 340 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054 + Details
Name: | us-gaap_CapitalizedContractCostNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 910 -SubTopic 310 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68065756&loc=d3e49370-109356 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -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 + Details
Name: | us-gaap_ContractReceivableRetainage
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in measure of progress which increases (decreases) right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045 + Details
Name: | us-gaap_ContractWithCustomerAssetCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of decrease in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time from transfer to receivable due to right to consideration becoming unconditional. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045 + Details
Name: | us-gaap_ContractWithCustomerAssetReclassifiedToReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045 + Details
Name: | us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of transaction price allocated to performance obligation that has not been recognized as revenue. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045 + Details
Name: | us-gaap_RevenueRemainingPerformanceObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=ghm_CustomerDepositsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |