Restructuring (Narrative) (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) Employee	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Document Period End Date	Mar. 31, 2017
Restructuring Charges	$ 7	$ 15
Restructuring Reserve	10		$ 6
T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 7
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee	335
Restructuring and Related Cost, Number of Positions Eliminated | Employee	240
Restructuring and Related Cost, Expected Cost	$ 40
Payments for Restructuring	2
International
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	4		$ 5
International | T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0
Payments for Restructuring	$ 0