Accounts Receivable (Schedule Of Accounts Receivable Under Long-Term Contracts) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Unbillable [Member]
Accounts, Notes, Loans and Financing Receivables [Line Items]
Current	$ 1,174	$ 994
Expected to be collected after one year	498	507
Total	1,672	1,501
Claims [Member]
Accounts, Notes, Loans and Financing Receivables [Line Items]
Current	49	30
Expected to be collected after one year	209	194
Total	$ 258	$ 224