Summary of Financial Information for Each Business Segment (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 28, 2014	Sep. 28, 2014
Segment Reporting Information [Line Items]
Reduction in CAS pension cost due to adoption of HATFA	$ (55)	$ (55)
First Six Months Of Twenty Fourteen
Segment Reporting Information [Line Items]
Reduction in CAS pension cost due to adoption of HATFA	$ (35)	$ (35)

Increase (decrease) in pension expense under US Government Cost Accounting Standards related to the adoption of the Highway and Transportation Funding Act of 2014.

No definition available.

Name:	lmt_IncreaseDecreaseInPensionExpenseUnderUSGovernmentCostAccountingStandardsRelatedToAdoptionOfHighwayAndTransportationFundingActOf2014
Namespace Prefix:	lmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration