Financial Instruments (Effect of Cash Flows Hedges on Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative [Line Items]
Portion of ending balance of gain (loss) expected to be reclassified into earnings over the next twelve months, after-tax	$ (3)
Cash Flow Hedging [Member]
Derivative [Line Items]
Beginning balance, after-tax	(18)	$ (13)	$ (6)	$ (48)
Additions and revaluations of derivatives designated as cash flow hedges, after-tax	5	(8)	(11)	16
Clearance of hedge results to earnings, after-tax	3	8	7	19
Ending balance, after-tax	$ (10)	$ (13)	$ (10)	$ (13)