Changes to Debt (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Debt Instrument [Line Items]
Debt maturing within one year, Balance at January 1, 2013	$ 4,369
Long-term debt, Balance at January 1, 2013	47,618
Total, Balance at January 1, 2013	51,987
Proceeds from long-term borrowings	49,166
Repayments of long-term borrowings and capital leases obligations	(2,392)	(2,878)
Decrease in short-term obligations, excluding current maturities	(324)	375
Other	703
Debt maturing within one year, Balance at September 30, 2013	8,202
Long-term debt, Balance at September 30, 2013	90,938
Total, Balance at September 30, 2013	99,140
Long-term Debt
Debt Instrument [Line Items]
Long-term debt, Balance at January 1, 2013	47,618
Proceeds from long-term borrowings	49,166
Repayments of long-term borrowings and capital leases obligations	(250)
Reclassifications of long-term debt	(6,045)
Other	449
Long-term debt, Balance at September 30, 2013	90,938
Debt Maturing Within One Year
Debt Instrument [Line Items]
Debt maturing within one year, Balance at January 1, 2013	4,369
Repayments of long-term borrowings and capital leases obligations	(2,142)
Decrease in short-term obligations, excluding current maturities	(324)
Reclassifications of long-term debt	6,045
Other	254
Debt maturing within one year, Balance at September 30, 2013	$ 8,202