Acquisitions and Divestitures, Goodwill, and Intangible Assets (Intangible Assets) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	$ 4,573	$ 4,564
Accumulated Amortization		(2,258)	(1,979)
Net Carrying Amount		2,315	2,585
Contract and Program Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1],[2]	3,776	3,771
Accumulated Amortization	[2]	(1,779)	(1,531)
Net Carrying Amount		1,997	2,240
Tradenames and Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	474	469
Accumulated Amortization		(195)	(177)
Net Carrying Amount		279	292
Technology and Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	164	165
Accumulated Amortization		(126)	(116)
Net Carrying Amount		38	49
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	159	159
Accumulated Amortization		(158)	(155)
Net Carrying Amount		$ 1	$ 4

[1] Change in gross carrying amounts consists primarily of adjustments for acquired intangible assets and foreign currency translation.

[2] Consists of acquired backlog and probable follow-on work and associated customer relationships.