Condensed Consolidating Financial Statements Narrative (Details)	6 Months Ended
Jul. 05, 2015
Consolidating Financial Statements [Abstract]
Percentage of owned subsidiaries (the guarantors)	100.00%

Percentage Of Owned Subsidiaries Guaranteed Fixed Rate Notes

No definition available.

Name:	gd_PercentageOfOwnedSubsidiariesGuaranteedFixedRateNotes
Namespace Prefix:	gd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration