Accounts Receivable, Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Receivables [Abstract]
Amounts billed or billable	$ 2,473				$ 2,421
Unbilled amounts	330				318
Allowance for doubtful accounts	(82)				(87)
Accounts Receivable, Net	2,721				2,652
Billable contracts receivable to be invoiced in the subsequent month	933				945
Accounts Receivable Sales Arrangements [Abstract]
Deferred proceeds receivables from sales of accounts receivables	63				73
Remaining account receivable sold and derecognized	563				580
Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable sales	602		822
Deferred proceeds	62		124
Loss on sales of accounts receivable	3		4
Estimated decrease to operating cash flows	$ 17	[1]	$ 11	[1]

[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.