Restructuring (Summary Of Changes To Restructuring-Related Liabilities) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Restructuring Cost and Reserve [Line Items]
Document Period End Date	Mar. 31, 2017
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016	$ 6
Restructuring expense	(7)	$ (15)
Balance as of March 31, 2017	10
International
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016	1
Balance as of March 31, 2017	6
International
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016	5
Balance as of March 31, 2017	4
2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring	(1)
2014 T15 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Payment for Restructuring	0
2014 T15 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Payment for Restructuring	(1)
T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	(7)
Payment for Restructuring	(2)
T17 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Restructuring expense	(7)
Payment for Restructuring	(2)
T17 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Restructuring expense	0
Payment for Restructuring	0
Personnel Related
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016	5
Balance as of March 31, 2017	9
Personnel Related | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring	(1)
Personnel Related | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	(7)
Payment for Restructuring	(2)
Facility Related
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016	1
Balance as of March 31, 2017	1
Facility Related | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring	0
Facility Related | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	0
Payment for Restructuring	$ 0