OTHER - Severance and Restructuring Charges (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Sep. 26, 2021	Mar. 28, 2021	Sep. 27, 2020	Sep. 26, 2021	Sep. 27, 2020
Accounting Policies [Abstract]
Severance and restructuring charges	$ 0	$ 36	$ 0	$ 36	$ 0
Severance and restructuring charges, after-tax		$ 28
Severance and restructuring charges, after-tax (in dollars per share)		$ 0.10

Severance and Restructuring Costs, Per Share, After-Tax

No definition available.

Name:	lmt_SeveranceAndRestructuringCostsPerShareAfterTax
Namespace Prefix:	lmt_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration