Accumulated Other Comprehensive Loss and Shareholders' Equity - Accumulated Other Comprehensive (Loss) Income Activity (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,603	$ 2,225	$ 3,588	$ 3,731	$ 2,225	$ 3,731
Other comprehensive income (loss) before reclassifications					69	(239)
Reclassification of (income) losses					(4)	16
Net other comprehensive income (loss)	34	31	(385)	162	65	(223)
Balance at end of period	1,240	1,603	2,920	3,588	1,240	2,920
Other comprehensive income (loss) before reclassification related to foreign current translation adjustment, loss on intra-equity foreign currency transaction					2	38
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period		(403)		(23)	(403)	(23)
Other comprehensive income (loss) before reclassifications					71	(247)
Reclassification of (income) losses					0	8
Net other comprehensive income (loss)					71	(239)
Balance at end of period	(332)		(262)		(332)	(262)
Derivative Instrument and Other Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period		12		6	12	6
Other comprehensive income (loss) before reclassifications					(2)	8
Reclassification of (income) losses					(4)	8
Net other comprehensive income (loss)					(6)	16
Balance at end of period	6		18		6	18
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(360)	(391)	141	(17)	(391)	(17)
Net other comprehensive income (loss)	34	31	(385)	162
Balance at end of period	$ (326)	$ (360)	$ (244)	$ 141	$ (326)	$ (244)
Adoption of ASU 2016-01
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment of accounting principle							$ 0
Adoption of ASU 2016-01 | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment of accounting principle							0
Adoption of ASU 2016-01 | Derivative Instrument and Other Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment of accounting principle							(4)
Adoption of ASU 2016-01 | Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment of accounting principle							$ (4)