Restructuring (Summary Of Changes To Restructuring-Related Liabilities) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Restructuring Cost and Reserve [Line Items]
Document Period End Date			Jun. 30, 2017
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			$ 6
Restructuring expense	$ (38)	$ (5)	(45)	$ (20)
Balance as of June 30, 2017	5		5
International
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			1
Balance as of June 30, 2017	1		1
International
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			5
Balance as of June 30, 2017	4		4
2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(2)
2014 T15 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(1)
2014 T15 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(1)
T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			(24)
Payment for Restructuring			(23)
T17 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Restructuring expense			(21)
Payment for Restructuring			(20)
T17 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Restructuring expense			(3)
Payment for Restructuring			(3)
Personnel Related
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			5
Balance as of June 30, 2017	4		4
Personnel Related | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(2)
Personnel Related | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			(12)
Payment for Restructuring			(11)
Facility Related
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			1
Balance as of June 30, 2017	1		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
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			0
Balance as of June 30, 2017	$ 0		0
Other Restructuring [Member] | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			0
Other Restructuring [Member] | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			(12)
Payment for Restructuring			$ (12)