Derivative Financial Instruments (Location And Amounts Of Pre-Tax Gains (Losses) On Cash Flow Hedge Derivatives Financial Instruments) (Details) - Cash Flow Hedging [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (effective portion)	$ 34	$ 9	$ 89	$ 10
Cost Of Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (effective portion)	29	7	75	8
Selling, General and Administrative Expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (effective portion)	5	2	14	2
Foreign Exchange Forward [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Derivative Gains/Losses Recognized in Accumulated Other Comprehensive Income (Loss) (effective portion)	$ 6	$ 63	$ 165	$ 78