Shareholders' Equity - Accumulated Other Comprehensive Income (Loss) - Components and Changes of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	$ (2,414)	$ (2,548)	$ (2,202)	$ (2,283)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	64	115	(237)	63
Amounts reclassified into income, net of taxes	21	19	19	19
Accumulated other comprehensive income (loss), net of tax, ending balance	(2,329)	(2,414)	(2,419)	(2,202)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(1,352)	(1,416)	(1,230)	(1,256)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(15)	64	(125)	26
Amounts reclassified into income, net of taxes	0	0	0	0
Accumulated other comprehensive income (loss), net of tax, ending balance	(1,367)	(1,352)	(1,355)	(1,230)
Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(998)	(1,040)	(988)	(1,005)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	24	0	0
Amounts reclassified into income, net of taxes	16	18	17	17
Accumulated other comprehensive income (loss), net of tax, ending balance	(982)	(998)	(971)	(988)
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(62)	(91)	16	(23)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	78	27	(111)	37
Amounts reclassified into income, net of taxes	5	2	2	2
Accumulated other comprehensive income (loss), net of tax, ending balance	$ 21	$ (62)	$ (93)	$ 16