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, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	$ (2,419)	$ (2,202)	$ (2,283)	$ (1,839)	$ (1,927)	$ (1,909)
Other comprehensive income before reclassifications, net of taxes	34	(237)	63	(68)	74	(32)
Amounts reclassified into income, net of taxes	19	19	19	10	14	14
Accumulated other comprehensive income (loss), net of tax, ending balance	(2,367)	(2,419)	(2,202)	(1,897)	(1,839)	(1,927)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(1,355)	(1,230)	(1,256)	(1,121)	(1,197)	(1,162)
Other comprehensive income before reclassifications, net of taxes	34	(125)	26	(68)	76	(35)
Amounts reclassified into income, net of taxes	0	0	0	0	0	0
Accumulated other comprehensive income (loss), net of tax, ending balance	(1,321)	(1,355)	(1,230)	(1,189)	(1,121)	(1,197)
Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(971)	(988)	(1,005)	(701)	(714)	(729)
Other comprehensive income before reclassifications, net of taxes	0	0	0	0	0	3
Amounts reclassified into income, net of taxes	17	17	17	12	13	13
Accumulated other comprehensive income (loss), net of tax, ending balance	(955)	(971)	(988)	(689)	(701)	(714)
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(93)	16	(23)	(17)	(16)	(17)
Other comprehensive income before reclassifications, net of taxes	0	(111)	37	0	(2)	(1)
Amounts reclassified into income, net of taxes	2	2	2	(2)	1	1
Accumulated other comprehensive income (loss), net of tax, ending balance	$ (91)	$ (93)	$ 16	$ (19)	$ (17)	$ (16)