Condensed Consolidating Financial Statements - Additional Information (Details)	9 Months Ended
Sep. 29, 2019
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