Accumulated Other Comprehensive Loss - Changes (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI roll forward
Beginning balance			$ 5,320
Other comprehensive income (loss), net of tax	$ 47	$ (14)	94	$ 64
Ending balance	5,300		5,300
Accumulated Other Comprehensive Loss [Member]
AOCI roll forward
Beginning balance			(80)
Other comprehensive income before reclassifications, net of tax			88
Amounts reclassified from accumulated other comprehensive loss net of tax			6
Other comprehensive income (loss), net of tax			94
Ending balance	14		14
Derivative Instrument [Member]
AOCI roll forward
Beginning balance			(40)
Amounts reclassified from accumulated other comprehensive loss net of tax			6
Other comprehensive income (loss), net of tax			6
Ending balance	(34)		(34)
Available for Sale Securities [Member]
AOCI roll forward
Beginning balance			13
Other comprehensive income before reclassifications, net of tax			2
Other comprehensive income (loss), net of tax			2
Ending balance	15		15
Foreign Currency Translation Adjustments [Member]
AOCI roll forward
Beginning balance			(47)
Other comprehensive income before reclassifications, net of tax			86
Other comprehensive income (loss), net of tax			86
Ending balance	39		39
Post - Retirement Benefit Obligation [Member]
AOCI roll forward
Beginning balance			(6)
Ending balance	$ (6)		$ (6)