Accumulated Other Comprehensive Loss - Changes (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI roll forward
Beginning balance	$ 6,467	$ 6,056	$ 6,276	$ 6,042
Other comprehensive income (loss), net of tax	(11)	33	54	(19)
Ending balance	6,787	6,241	6,787	6,241
Accumulated Other Comprehensive Loss [Member]
AOCI roll forward
Beginning balance	(22)	(49)	(87)	8
Other comprehensive income (loss) before reclassifications, net of tax			49
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax			5
Other comprehensive income (loss), net of tax	(11)	33	54	(19)
Ending balance	(33)	$ (16)	(33)	$ (16)
Derivative Instruments [Member]
AOCI roll forward
Beginning balance			(32)
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax			6
Other comprehensive income (loss), net of tax			6
Ending balance	(26)		(26)
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			13
Other comprehensive income (loss), net of tax			13
Ending balance	36		36
Foreign Currency Translation Adjustments [Member]
AOCI roll forward
Beginning balance			(76)
Other comprehensive income (loss) before reclassifications, net of tax			36
Other comprehensive income (loss), net of tax			36
Ending balance	(40)		(40)
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)