XML 48 R35.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Debt (Tables) | 12 Months Ended
--- | ---
Mar. 31, 2017
Debt Disclosure [Abstract] |
Long-term Capital Lease Obligations Outstanding | The Company and its subsidiaries had long-term capital lease obligations outstanding as follows:
|  | March 31, |
|  | 2017 |  |  | 2016 |
Capital lease obligations (Note 6) |  | $ | 250 |  |  | $ | 212 |
Less: current amounts |  |  | 107 |  |  |  | 55 |
Total |  | $ | 143 |  |  | $ | 157 |

X
- Definition Schedule of capital lease obligations. + References No definition available. + Details
Name: | ghm_ScheduleOfCapitalLeaseObligationsTableTextBlock
Namespace Prefix: | ghm_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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