Restructuring (Narrative) (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Employee	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Document Period End Date			Jun. 30, 2017
Restructuring Charges	$ 38	$ 5	$ 45	$ 20
Restructuring Reserve	5		5		$ 6
T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 24
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee			535
Restructuring and Related Cost, Number of Positions Eliminated | Employee			410
Restructuring and Related Cost, Expected Cost	10		$ 10
Payments for Restructuring			23
International
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 4		4		$ 5
International | T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			3
Payments for Restructuring			$ 3