XML 64 R56.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Leases - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2023 | Dec. 31, 2022
Leases [Line Items] |  |  |  |
Operating Lease Payments | $ 243 | $ 211 | $ 709 | $ 632
Remainder operating lease payment | 243 |  | 243 |
Future fixed minimum lease payments | $ 6,028 |  | $ 6,028 |

X
- Definition Future fixed minimum lease payments. + References No definition available. + Details
Name: | ghm_FutureFixedMinimumLeasePayments
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Leases. + References No definition available. + Details
Name: | ghm_LeasesLineItems
Namespace Prefix: | ghm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Remainder Operating Lease Payment. + References No definition available. + Details
Name: | ghm_RemainderOperatingLeasePayment
Namespace Prefix: | ghm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 5 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479041/842-20-45-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (g)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_OperatingLeasePayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration