Accounts Receivable, Net (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Receivables [Abstract]
Amounts billed or billable		$ 2,399		$ 2,399		$ 2,421
Unbilled amounts		294		294		318
Allowance for doubtful accounts		(81)		(81)		(87)
Accounts Receivable, Net		2,612		2,612		2,652
Billable contracts receivable to be invoiced in the subsequent month		875		875		945
Accounts Receivable Sales Arrangements [Abstract]
Remaining account receivable sold and derecognized		516		516		580
Accounts, Notes, Loans and Financing Receivable [Line Items]
Estimated decrease to operating cash flows		(67)	$ (102)	(228)	$ (337)
Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable sales		551	696	1,739	2,244
Deferred proceeds		67	94	186	314
Loss on sales of accounts receivable		3	4	9	12
Estimated decrease to operating cash flows	[1]	(31)	$ (22)	(45)	$ (42)
Other Current Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred proceeds receivables from sales of accounts receivables		$ 68		$ 68		$ 73

[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.