Derivatives and Hedging - Interest Rate Management Risk Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Estimated pretax losses currently included within Accumulated Other Comprehensive Loss that will be reclassified to earnings in next twelve months	$ 11		$ 11
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Derivative gain (loss)	$ 2	$ (15)	$ 1	$ (6)