Restructuring (Summary Of Changes To Restructuring-Related Liabilities) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Document Period End Date			Sep. 30, 2017
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			$ 6
Restructuring expense	$ (7)	$ (6)	(52)	$ (26)
Balance as of September 30, 2017	3		3
International
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			1
Balance as of September 30, 2017	1		1
International
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			5
Balance as of September 30, 2017	2		2
2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(3)
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			(2)
2015 Acquisition Integration [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(1)
2015 Acquisition Integration [Member] | International
Restructuring Reserve [Roll Forward]
Payment for Restructuring			0
2015 Acquisition Integration [Member] | International
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(1)
T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			(31)
Payment for Restructuring			(30)
T17 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Restructuring expense			(24)
Payment for Restructuring			(23)
T17 Restructuring [Member] | International
Restructuring Reserve [Roll Forward]
Restructuring expense			(7)
Payment for Restructuring			(7)
Personnel Related
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			5
Balance as of September 30, 2017	3		3
Personnel Related | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(3)
Personnel Related | 2015 Acquisition Integration [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			(1)
Personnel Related | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			(17)
Payment for Restructuring			(15)
Facility Related
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			1
Balance as of September 30, 2017	0		0
Facility Related | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			0
Facility Related | 2015 Acquisition Integration [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			0
Facility Related | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			0
Payment for Restructuring			(1)
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2016			0
Balance as of September 30, 2017	$ 0		0
Other Restructuring [Member] | 2014 T15 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			0
Other Restructuring [Member] | 2015 Acquisition Integration [Member]
Restructuring Reserve [Roll Forward]
Payment for Restructuring			0
Other Restructuring [Member] | T17 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			(14)
Payment for Restructuring			$ (14)