LEGAL PROCEEDINGS AND CONTINGENCIES (Details) $ in Millions		1 Months Ended	6 Months Ended	12 Months Ended
	Aug. 16, 2016 USD ($)	Dec. 31, 2014	Jun. 30, 2019 USD ($) subsidiary	Dec. 31, 2018 USD ($)	Dec. 31, 2016	May 31, 2017 lawsuit	Apr. 24, 2009 USD ($)
Loss Contingencies [Line Items]
Damages sought by plaintiff			$ 52
Liabilities recorded relative to environmental matters			823	$ 864
Environmental costs eligible for future recovery			$ 715	750
Period over which costs and recovery of costs is projected			20 years
Outstanding letters of credit, surety bonds, and third-party guarantees			$ 3,500	3,600
Third-party guarantees			$ 1,100	$ 850
Guarantees of contractual performance of joint ventures (as a percent)			72.00%	65.00%
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%
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
Sikorsky Aircraft Corporation
Loss Contingencies [Line Items]
Number of pending claims | lawsuit						2
Number of entities involved in litigation | subsidiary			2