XML 67 R54.htm IDEA: XBRL DOCUMENT v3.21.1

Leases - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Line Items]
Lessee, option to renew or terminate leases, description	Certain leases include options to renew or terminate. Renewal options are exercisable per the discretion of the Company and vary based on the nature of each lease.
ROU assets obtained in exchange for operating lease liability	$ 0	$ 223
Minimum [Member]
Leases [Line Items]
Remaining term of contract	1 year
Maximum [Member]
Leases [Line Items]
Remaining term of contract	5 years

X

- Definition

Leases.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Lessee operating and finance lease remaining term of contract.

+ References

No definition available.

+ Details

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

X

- Definition

Lessee operating lease and finance lease option to renew or terminate.

+ References

No definition available.

+ Details

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Namespace Prefix:	ghm_
Data Type:	xbrli:stringItemType
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X

- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(2)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

+ Details

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Period Type:	duration

X

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