Shareholders' Equity - Accumulated Other Comprehensive Income (Loss) - Components and Changes of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	$ (1,839)	$ (1,927)	$ (1,909)	$ (1,704)	$ (1,740)	$ (1,723)
Other comprehensive (loss) income before reclassifications, net of taxes	(68)	74	(32)	(210)	128	(36)
Amounts reclassified into income, net of taxes	10	14	14	13	11	18
Tax effects reclassified into retained earnings					(103)
Accumulated other comprehensive income (loss), net of tax, ending balance	(1,897)	(1,839)	(1,927)	(1,902)	(1,704)	(1,740)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(1,121)	(1,197)	(1,162)	(909)	(1,037)	(1,001)
Other comprehensive (loss) income before reclassifications, net of taxes	(68)	76	(35)	(214)	128	(36)
Amounts reclassified into income, net of taxes	0	0	0	0	0	0
Tax effects reclassified into retained earnings					0
Accumulated other comprehensive income (loss), net of tax, ending balance	(1,189)	(1,121)	(1,197)	(1,123)	(909)	(1,037)
Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(701)	(714)	(729)	(776)	(686)	(703)
Other comprehensive (loss) income before reclassifications, net of taxes	0	0	3	4	0	0
Amounts reclassified into income, net of taxes	12	13	13	12	9	17
Tax effects reclassified into retained earnings					(99)
Accumulated other comprehensive income (loss), net of tax, ending balance	(689)	(701)	(714)	(760)	(776)	(686)
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(17)	(16)	(17)	(20)	(17)	(18)
Other comprehensive (loss) income before reclassifications, net of taxes	0	(2)	(1)	0	0	0
Amounts reclassified into income, net of taxes	(2)	1	1	1	2	1
Tax effects reclassified into retained earnings					(4)
Accumulated other comprehensive income (loss), net of tax, ending balance	$ (19)	$ (17)	$ (16)	$ (18)	$ (20)	$ (17)