Supplementary Information - Cash Paid for Interest and Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Abstract]
Interest	$ 346	$ 389	$ 369
Income tax	$ 1,567	$ 2,048	$ 1,729