Loss Contingency, Pending Claims, Number Of Deceased Parties

No definition available.

Name:	ajrd_LossContingencyPendingClaimsNumberOfDeceasedParties
Namespace Prefix:	ajrd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loss Contingency, Pending Claims, Number of Injured Parties

+ References

No definition available.

+ Details

Name:	ajrd_LossContingencyPendingClaimsNumberofInjuredParties
Namespace Prefix:	ajrd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number Of Lawsuits

+ References

No definition available.

+ Details

Name:	ajrd_NumberOfLawsuits
Namespace Prefix:	ajrd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

+ Details

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

+ Details

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_LitigationCaseAxis=ajrd_AsbestosLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=ajrd_SocorroLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=ajrd_JamesChavezAndrewBacaandSpousesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=ajrd_OccupationalSafetyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=ajrd_StateofCaliforniaDivisionofOccupationalSafetyHealthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_EntityByLocationAxis=ajrd_RanchoCordovaFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_SettledLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=ajrd_InflectiveInc.LitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Narrative - Legal Matters (Details)	Sep. 30, 2017 USD ($) case	Jan. 16, 2015 USD ($)	Dec. 18, 2014 USD ($)	Nov. 30, 2013 employee
Asbestos Litigation
Loss Contingencies [Line Items]
Unresolved asbestos cases pending \| case	63
Socorro Litigation \| James Chavez, Andrew Baca, and Spouses
Loss Contingencies [Line Items]
Litigation liability accrued	$ 0
Occupational Safety \| State of California, Division of Occupational Safety & Health \| Rancho Cordova Facility
Loss Contingencies [Line Items]
Number of injured employees \| employee				2
Number of deceased employees \| employee				1
Damages		$ 100,000
Settled litigation \| Inflective Inc. Litigation
Loss Contingencies [Line Items]
Damages			$ 3,000,000