Derivative Instruments and Hedging Activities - Pre-tax Gains (Losses) (Details) - Not designated as a hedge - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative instruments and hedging activities
Total gain (loss)	$ (1)	$ 0	$ (1)	$ (3)
Foreign currency exchange contracts | Other, net
Derivative instruments and hedging activities
Total gain (loss)	0	(1)	1	(1)
Forward contracts | Other, net
Derivative instruments and hedging activities
Total gain (loss)	(1)	1	(1)	1
Interest rate swaps
Derivative instruments and hedging activities
Total gain (loss)	$ 0	$ 0	$ (1)	$ (3)