Segment Information - Revenue by Geographic Area (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenue	$ 48,580	$ 45,266	$ 41,731
Operating Segments
Segment Reporting Information [Line Items]
Revenue	48,580	45,266	41,731
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenue	16,151	13,897	13,535
Operating Segments | Latin America
Segment Reporting Information [Line Items]
Revenue	7,699	7,754	7,554
Operating Segments | Europe/CIS/Africa
Segment Reporting Information [Line Items]
Revenue	12,515	12,411	11,510
Operating Segments | Middle East & Asia
Segment Reporting Information [Line Items]
Revenue	11,875	10,767	8,717
Eliminations & other
Segment Reporting Information [Line Items]
Revenue	$ 340	$ 437	$ 415