Accumulated Other Comprehensive Loss - Changes (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI roll forward
Beginning balance	$ 6,417	$ 6,065	$ 6,276	$ 6,042
Other comprehensive income (loss), net of tax	31	(21)	65	(52)
Ending balance	6,467	6,056	6,467	6,056
Accumulated Other Comprehensive Loss [Member]
AOCI roll forward
Beginning balance	(53)	(28)	(87)	8
Other comprehensive income (loss) before reclassifications, net of tax			62
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax			3
Other comprehensive income (loss), net of tax	31	(21)	65	(52)
Ending balance	(22)	$ (49)	(22)	$ (49)
Derivative Instruments [Member]
AOCI roll forward
Beginning balance			(32)
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax			4
Other comprehensive income (loss), net of tax			4
Ending balance	(28)		(28)
Derivative Instruments [Member] | Foreign Currency Derivatives [Member]
AOCI roll forward
Outstanding derivatives	0		0
Available for sale Securities [Member]
AOCI roll forward
Beginning balance			23
Other comprehensive income (loss) before reclassifications, net of tax			9
Other comprehensive income (loss), net of tax			9
Ending balance	32		32
Foreign Currency Translation Adjustments [Member]
AOCI roll forward
Beginning balance			(76)
Other comprehensive income (loss) before reclassifications, net of tax			53
Other comprehensive income (loss), net of tax			53
Ending balance	(23)		(23)
Post - Retirement Benefit Obligation [Member]
AOCI roll forward
Beginning balance			(2)
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax			(1)
Other comprehensive income (loss), net of tax			(1)
Ending balance	$ (3)		$ (3)