Graham Corporation Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Cover
- Document and Entity Information
Financial Statements
Notes to Financial Statements
Notes Tables
Notes Details

Income Taxes - Additional Information (Detail)

v3.8.0.1

Income Taxes - Additional Information (Detail) - USD ($)		3 Months Ended	9 Months Ended
	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2017	Mar. 31, 2017
Income Taxes [Line Items]
Liability unrecognized tax benefits		$ 0	$ 0	$ 0
Percentage of corporate income tax rate			35.00%
Income tax benefit from remeasurement of deferred tax assets and liabilities		1,575,000	$ 1,575,000
One-time transition tax on accumulated foreign earnings		$ 137,000
Subsequent Event [Member]
Income Taxes [Line Items]
Percentage of corporate income tax rate	21.00%
Earliest Tax Year [Member] \| Federal Tax Jurisdictions [Member]
Income Taxes [Line Items]
Open tax year			2015
Earliest Tax Year [Member] \| State Tax Jurisdictions [Member]
Income Taxes [Line Items]
Open tax year			2013
Earliest Tax Year [Member] \| International Tax Jurisdictions [Member]
Income Taxes [Line Items]
Open tax year			2014
Latest Tax Year [Member] \| Federal Tax Jurisdictions [Member]
Income Taxes [Line Items]
Open tax year			2017
Latest Tax Year [Member] \| State Tax Jurisdictions [Member]
Income Taxes [Line Items]
Open tax year			2017
Latest Tax Year [Member] \| International Tax Jurisdictions [Member]
Income Taxes [Line Items]
Open tax year			2016

- Definition

Income taxes.

+ References

No definition available.

+ Details

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

- Definition

One-time transition tax on accumulated post-1986 earnings and profits of foreign subsidiary previously deferred from U.S. income taxes.

+ References

No definition available.

+ Details

Name:	ghm_TransitionTaxOnAccumulatedForeignEarnings
Namespace Prefix:	ghm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of income tax expense (benefit) from continuing operations attributable to an adjustment of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319

+ Details

Name:	us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Tax year that remains open to examination under enacted tax laws, in CCYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

+ Details

Name:	us-gaap_OpenTaxYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

+ Details

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_EarliestTaxYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_LatestTaxYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: