Commitments and Contingencies - Narrative - Environmental Matters (Details)						6 Months Ended	12 Months Ended	36 Months Ended
	Feb. 28, 2015 a	Sep. 20, 2011 unilateral_administrative_order	Mar. 14, 2008 a	May. 09, 2002	Jun. 30, 2000 respondent	May. 31, 2015 USD ($) respondent LegalMatter	Dec. 31, 2002 USD ($) a	Dec. 31, 1997 respondent	Nov. 30, 2014 USD ($)	Mar. 28, 2014	Mar. 27, 2014	Oct. 31, 2001 USD ($)
Site Contingency [Line Items]
Accrued environmental costs						$ 161,500,000			$ 166,000,000
Guarantee obligations						120,000,000.0
Non-contaminated land | a	6,000
Chubb Custom Insurance Company [Member] | Aerojet-General Corporation v. Chubb Custom Insurance Company [Member]
Site Contingency [Line Items]
Litigation settlement award to (against)						(2,000,000)
Fairchild Corporation [Member] | Aerojet-General Corporation v. Chubb Custom Insurance Company [Member]
Site Contingency [Line Items]
Litigation settlement award to (against)						300,000
Cooperating Respondents [Member] | Aerojet-General Corporation v. Chubb Custom Insurance Company [Member]
Site Contingency [Line Items]
Damages sought						$ 3,300,000
Various Environmental Matters [Member]
Site Contingency [Line Items]
Number of environmental remediation matters | LegalMatter						40
Environmental remediation term						15 years
Accrued environmental costs						$ 161,500,000
Various Environmental Matters [Member] | Minimum [Member]
Site Contingency [Line Items]
Estimated environmental costs						161,500,000
Various Environmental Matters [Member] | Maximum [Member]
Site Contingency [Line Items]
Estimated environmental costs						$ 276,300,000
Various Environmental Matters [Member] | Contracting business [Member]
Site Contingency [Line Items]
Environmental obligation funding percent						97.00%
Various Environmental Matters [Member] | Sacramento, California [Member]
Site Contingency [Line Items]
Accrued environmental costs						$ 133,200,000
Guarantee obligations							$ 75,000,000
Various Environmental Matters [Member] | Sacramento, California [Member] | Previously Reported [Member]
Site Contingency [Line Items]
Guarantee obligations							$ 20,000,000
Various Environmental Matters [Member] | Sacramento, California [Member] | Minimum [Member]
Site Contingency [Line Items]
Estimated environmental costs						133,200,000
Various Environmental Matters [Member] | Sacramento, California [Member] | Maximum [Member]
Site Contingency [Line Items]
Estimated environmental costs						215,800,000
Various Environmental Matters [Member] | Sacramento, California [Member] | Environmental Protection Agency [Member]
Site Contingency [Line Items]
Non-contaminated land | a							2,600
Number of Unilateral Administrative Orders | unilateral_administrative_order		2
Various Environmental Matters [Member] | Sacramento, California [Member] | Department of Toxic Substances Control [Member]
Site Contingency [Line Items]
Non-contaminated land | a			400
Various Environmental Matters [Member] | Baldwin Park Operable Unit [Member]
Site Contingency [Line Items]
Accrued environmental costs						$ 15,500,000
Guarantee obligations												$ 25,000,000
Management agreement terms				15 years
Number of other respondents | respondent						2
Reserve accrued						$ 0
Various Environmental Matters [Member] | Baldwin Park Operable Unit [Member] | Minimum [Member]
Site Contingency [Line Items]
Estimated environmental costs						15,500,000
Various Environmental Matters [Member] | Baldwin Park Operable Unit [Member] | Maximum [Member]
Site Contingency [Line Items]
Estimated environmental costs						33,500,000
Various Environmental Matters [Member] | Baldwin Park Operable Unit [Member] | Aerojet Rocketdyne, Inc. [Member]
Site Contingency [Line Items]
Percentage of responsibility in all project costs										70.00%	68.00%
Various Environmental Matters [Member] | Baldwin Park Operable Unit [Member] | Environmental Protection Agency [Member]
Site Contingency [Line Items]
Number of other respondents | respondent					7			18
Various Environmental Matters [Member] | Toledo, Ohio [Member]
Site Contingency [Line Items]
Estimated range of anticipated costs for NRD matter, low						0
Estimated range of anticipated costs for NRD matter, high						200,000
Expenditures recoverable						0
Various Environmental Matters [Member] | Wabash, Indiana [Member]
Site Contingency [Line Items]
Accrued environmental costs						700,000
Expenditures recoverable						0
Various Environmental Matters [Member] | Wabash, Indiana [Member] | Minimum [Member]
Site Contingency [Line Items]
Estimated environmental costs						700,000
Various Environmental Matters [Member] | Wabash, Indiana [Member] | Maximum [Member]
Site Contingency [Line Items]
Estimated environmental costs						$ 1,100,000