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Income Tax - Additional Information (Detail) (USD $)
Apr. 05, 2015
Income Tax Disclosure [Abstract]  
Possible chance of tax position sustained, percentage 50.00%gd_PossibleChanceOfTaxPositionSustainablePercentage
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit $ 0us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit