Accounts Receivable, Net (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable, Net [Abstract]
Total accounts receivable	$ 4,055	$ 3,362
Allowance for doubtful accounts	(79)	(63)
Total accounts receivable, net	3,976	3,299
US Government
Accounts Receivable, Net [Abstract]
Billed	656	482
Unbilled	10,818	9,730
Progress and performance-based payments received	(8,068)	(7,484)
Total accounts receivable	3,406	2,728
Other Customers
Accounts Receivable, Net [Abstract]
Billed	218	200
Unbilled	3,397	3,895
Progress and performance-based payments received	(2,966)	(3,461)
Total accounts receivable	$ 649	$ 634