Accounts Receivable, Net (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable
Accounts receivable expected to be collected in 2014	$ 66
Accounts receivable expected to be collected in 2015	136
Total accounts receivable	909	714
Allowance for doubtful accounts	(4)	(3)
Total accounts receivable, net	905	711
Due From U.S. Government
Accounts, Notes, Loans and Financing Receivable
Amounts billed	158	119
Recoverable costs and accrued profit on progress completed - unbilled	701	557
Total accounts receivable	859	676
Due From Other Customers
Accounts, Notes, Loans and Financing Receivable
Amounts billed	33	16
Recoverable costs and accrued profit on progress completed - unbilled	17	22
Total accounts receivable	$ 50	$ 38