Commitments and Contingency - Additional Information (Detail) $ in Billions	9 Months Ended
Oct. 04, 2015 USD ($)
Commitments and Contingencies [Line Items]
Letters of credit and guarantees	$ 1
Maximum
Commitments and Contingencies [Line Items]
Period preceding delivery of aircraft to customer fair market value of trade-in aircraft is established, days, maximum	120 days

Letters of credit, bank guarantees, surety bonds, and other similar arrangements entered into with financial institutions and insurance carriers.

No definition available.

Name:	gd_LettersOfCreditAndGuarantees
Namespace Prefix:	gd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant