LEGAL PROCEEDINGS AND CONTINGENCIES (Details) $ in Millions			1 Months Ended	3 Months Ended	6 Months Ended
	Apr. 05, 2021 USD ($)	Aug. 16, 2016 USD ($)	Dec. 31, 2014	Mar. 28, 2021 USD ($) subsidiary	Jun. 28, 2020	Dec. 31, 2020 USD ($)	May 31, 2017 lawsuit	Apr. 24, 2009 USD ($)
Loss Contingencies [Line Items]
Damages sought by plaintiff				$ 52
Liabilities recorded relative to environmental matters				778		$ 789
Environmental costs eligible for future recovery				$ 675		685
Period over which costs and recovery of costs is projected				20 years
Outstanding letters of credit, surety bonds, and third-party guarantees				$ 3,300		3,400
Third-party guarantees				$ 867		$ 871
Guarantees of contractual performance of joint ventures (as a percent)				70.00%	71.00%
Subsequent Event
Loss Contingencies [Line Items]
Amount agreed to resolve remaining claims	$ 6
N.Y. Metropolitan Transportation Authority
Loss Contingencies [Line Items]
Damages sought by plaintiff				$ 190
Contract value								$ 323
Contract payments received to date				241
Claims for monetary damages against the plaintiff				$ 95
Period of bench trial			35 days
Leidos Holdings, Inc.
Loss Contingencies [Line Items]
Reserve transferred		$ 38
Indemnification percent, up to maximum reserve		100.00%
Maximum reserve		$ 64
Indemnification percent in excess of maximum reserve		50.00%
Sikorsky Aircraft Corporation
Loss Contingencies [Line Items]
Number of pending claims | lawsuit							2
Number of entities involved in litigation | subsidiary				2