Basis of Presentation (Unaudited) (Details 3) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Change in Contract with Customer, Asset and Liability [Abstract]
Unbilled receivables, net	$ 3,869		$ 3,465
Amount of increase (decrease) in Unbilled Receivables	$ 404
Percent increase (decrease) in Unbilled Receivables	12.00%
Advance payments and amounts in excess of costs incurred	$ (1,479)		(1,761)
Amount of decrease (increase) in Customer Advances	$ 282
Percent decrease (increase) in Customer Advances	(16.00%)
Contract with Customer, Asset, Net, Current	$ 2,390		$ 1,704
Amount of increase (decrease) in net contract assets (liabilities)	$ 686
Percent increase (decrease) in net contract assets (liabilities)	40.00%
Change in Contract with Customer, Liability [Abstract]
Contract with Customer, Liability, Revenue Recognized	$ 706	$ 578