Accounts Receivable, Net (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Receivables [Abstract]
Amounts billed or billable		$ 2,180		$ 2,180		$ 2,110
Unbilled amounts		360		360		289
Allowance for doubtful accounts		(74)		(74)		(80)
Accounts Receivable, Net		2,466		2,466		2,319
Billable contracts receivable to be invoiced in the subsequent month		843		843		849
Accounts Receivable Sales Arrangements [Abstract]
Remaining account receivable sold and derecognized		540		540		660
Accounts, Notes, Loans and Financing Receivable [Line Items]
Estimated decrease to operating cash flows		(35)	$ (67)	(127)	$ (228)
Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable sales		591	551	1,919	1,739
Deferred proceeds		54	67	184	186
Loss on sales of accounts receivable		4	3	12	9
Estimated decrease to operating cash flows	[1]	(60)	$ (31)	(114)	$ (45)
Other Current Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred proceeds receivables from sales of accounts receivables		$ 55		$ 55		$ 61

[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.