XML 23 R28.htm IDEA: XBRL DOCUMENT v2.4.0.6

Revenue Recognition (Details)	9 Months Ended
	Dec. 31, 2012 Hour
Revenue Recognition (Textual) [Abstract]
Company Recognizes Planned Manufacturing Process	28 days
Direct labor hours worked on contracts	575
Substantial Completion of Manufacturing Process	95.00%

X

- Definition

Planned manufacturing process used in determining the applicable revenue recognition method.

+ References

No definition available.

+ Details

Name:	ghm_CompanyRecognizesPlannedManufacturingProcess
Namespace Prefix:	ghm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Equivalent of four weeks of direct labor hours worked on contracts.

+ References

No definition available.

+ Details

Name:	ghm_EquivalentOfFourWeeksOfDirectLaborHoursWorkedOnContracts
Namespace Prefix:	ghm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	ghm_RevenueRecognitionTextualAbstract
Namespace Prefix:	ghm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- 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

Name:	ghm_SubstantialCompletionOfManufacturingProcess
Namespace Prefix:	ghm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration