Expenses Incurred Related to Business Acquisition

No definition available.

Name:	gy_ExpensesIncurredRelatedToBusinessAcquisition
Namespace Prefix:	gy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Legal Settlement

+ References

No definition available.

+ Details

Name:	gy_LegalSettlement
Namespace Prefix:	gy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

For a debtor, the aggregate gain (loss) recognized on the restructuring of payables arises from the difference between the book value of the debt before the restructuring and the fair value of the payments on the debt after restructuring is complete.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 60

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6402221&loc=d3e15743-112638

+ Details

Name:	us-gaap_GainsLossesOnRestructuringOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of payroll tax expense, compensation, postemployment and benefit-related expenses not elsewhere specified in the taxonomy (such as health plan, profit sharing, incentives, tuition reimbursement, other fringe benefits and perquisites) incurred in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.4)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Definition

This element may be used to disclose other activity associated with temporary equity that is not separately disclosed.

+ References

No definition available.

+ Details

Name:	us-gaap_TemporaryEquityOtherChanges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_UnusualOrInfrequentItemLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Unusual Items - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	May 31, 2014	May 31, 2013	Feb. 28, 2013	May 31, 2014	May 31, 2013
Unusual or Infrequent Item [Line Items]
Loss on bank amendment	$ 0.2	$ 0		$ 0.2	$ 0
Realized losses (gains) and interest				0.1	(0.1)
Charge related to legal settlement			0.5
Expenses incurred related to Rocketdyne Business acquisition					11.8
Internal labor costs					1.1
Senior Credit Facility [Member]
Unusual or Infrequent Item [Line Items]
Loss on bank amendment				$ 0.2