Restructuring (Narrative) (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Employee	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Document Period End Date			Sep. 30, 2017
Restructuring Charges	$ 7	$ 6	$ 52	$ 26
Restructuring Reserve	3		3		$ 6
T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 31
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee			620
Restructuring and Related Cost, Number of Positions Eliminated | Employee			595
Restructuring and Related Cost, Expected Cost	4		$ 4
Payments for Restructuring			30
International
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 2		2		$ 5
International | T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			7
Payments for Restructuring			$ 7