Legal Proceedings, Commitments and Contingencies (Detail) $ in Millions		1 Months Ended	12 Months Ended
	Aug. 16, 2016 USD ($)	Dec. 31, 2014	Dec. 31, 2020 USD ($) subsidiary	Dec. 31, 2019 USD ($)	May 31, 2017 lawsuit	Apr. 24, 2009 USD ($)
Loss Contingencies [Line Items]
Damages sought by plaintiff			$ 52
Liabilities recorded relative to environmental matters			789	$ 810
Environmental costs eligible for future recovery			$ 685	703
Time period environmental costs and recovery of environmental costs are projected over			20 years
Outstanding letters of credit, surety bonds, and third-party guarantees			$ 3,400	3,600
Third-party guarantees outstanding			$ 871	$ 996
Percentage of total guarantees that relate to guarantees of contractual performance of joint ventures			71.00%	76.00%
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
Loss contingency, 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 lawsuits | lawsuit					2
Number of entities involved in litigation | subsidiary			2