Accumulated Other Comprehensive Loss - Changes (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
AOCI roll forward
Beginning balance	$ 6,276	$ 6,042
Other comprehensive income (loss), net of tax	34	(31)
Ending balance	6,417	6,065
Accumulated Other Comprehensive Loss [Member]
AOCI roll forward
Beginning balance	(87)	8
Other comprehensive income (loss) before reclassifications, net of tax	33
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	1
Other comprehensive income (loss), net of tax	34	(31)
Ending balance	(53)	$ (28)
Derivative Instruments [Member]
AOCI roll forward
Beginning balance	(32)
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	2
Other comprehensive income (loss), net of tax	2
Ending balance	(30)
Derivative Instruments [Member] | Foreign Currency Derivatives [Member]
AOCI roll forward
Outstanding derivatives	0
Available for sale Securities [Member]
AOCI roll forward
Beginning balance	23
Other comprehensive income (loss) before reclassifications, net of tax	5
Other comprehensive income (loss), net of tax	5
Ending balance	28
Foreign Currency Translation Adjustments [Member]
AOCI roll forward
Beginning balance	(76)
Other comprehensive income (loss) before reclassifications, net of tax	28
Other comprehensive income (loss), net of tax	28
Ending balance	(48)
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)