Segment Information - Revenue by Geographic Area (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 30,440	$ 27,810	$ 35,475
Operating Segments
Segment Reporting Information [Line Items]
Revenue	30,440	27,810	35,475
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenue	9,487	6,665	9,811
Operating Segments | Latin America
Segment Reporting Information [Line Items]
Revenue	3,976	4,230	6,014
Operating Segments | Europe/CIS/Africa
Segment Reporting Information [Line Items]
Revenue	7,047	7,351	9,284
Operating Segments | Middle East & Asia
Segment Reporting Information [Line Items]
Revenue	9,419	9,286	9,898
Eliminations & other
Segment Reporting Information [Line Items]
Revenue	$ 511	$ 278	$ 468