Derivative Instruments (Change in Unrealized (Losses) Gains in Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net unrealized gains (losses) on cash flow hedges, net of taxes, beginning of period			$ 194
Net unrealized gains (losses) on cash flow hedges, net of taxes, end of period	$ 376		376
Unrealized Gain (Loss) on Forward Exchange Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net unrealized gains (losses) on cash flow hedges, net of taxes, beginning of period	2	$ 0	(1)	$ (1)
Change in fair value, net of tax	0	(1)	4	0
Reclassification into earnings, net of tax	(1)	0	(2)	0
Net unrealized gains (losses) on cash flow hedges, net of taxes, end of period	$ 1	$ (1)	$ 1	$ (1)