Derivatives and Other Hedging Instruments (Effect of Cash Flow Hedges on Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013 Cash Flow Hedging [Member]	Dec. 31, 2012 Cash Flow Hedging [Member]
Derivative [Line Items]
Beginning balance, after-tax		$ 3	$ 41
Additions and revaluations of derivatives designated as cash flow hedges, after-tax		(36)	(1)
Clearance of hedge results to earnings, after-tax		(15)	(37)
Ending balance, after-tax		(48)	3
Portion of ending balance expected to be reclassified into earnings over the next twelve months, after-tax	$ (36)