Receivables, net (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total receivables, net	$ 8,603	$ 8,202
U.S. Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amounts billed	1,433	792
Unbilled costs and accrued profits	6,337	6,877
Less: customer advances and progress payments	(1,042)	(1,346)
Total receivables, net	6,728	6,323
Other governments and commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amounts billed	687	546
Unbilled costs and accrued profits	1,651	1,847
Less: customer advances and progress payments	(463)	(514)
Total receivables, net	$ 1,875	$ 1,879