Accounts Receivable, Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			3 Months Ended				9 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Accounts Receivable [Member]		Sep. 30, 2012 Accounts Receivable [Member]		Sep. 30, 2013 Accounts Receivable [Member]		Sep. 30, 2012 Accounts Receivable [Member]
Receivables [Abstract]
Amounts billed or billable		$ 2,705	$ 2,639
Unbilled amounts		395	335
Allowance for doubtful accounts		(111)	(108)
Accounts Receivable, Net		2,989	2,866
Billable contracts receivable to be invoiced in the subsequent month		1,045	1,049
Accounts Receivable Sales Arrangements [Abstract]
Deferred proceeds receivables from sales of accounts receivables		129	116
Remaining account receivable sold and derecognized		740	766
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable sales				814		725		2,587		2,816
Deferred proceeds				125		122		384		525
Loss on sales of accounts receivable				4		4		13		16
Estimated decrease to operating cash flows				(75)	[1]	(266)	[1]	(42)	[1]	(168)	[1]
Payments to Acquire Receivables	$ (215)

[1] Represents the difference between current and prior period receivable sales adjusted for the effects of: (i) the deferred proceeds, (ii) collections prior to the end of the quarter and (iii) currency. The three months ended September 30, 2012 includes $215 of cash outflows related to our terminated U.S. revolving facility.