Debt - Additional Information (Detail) (USD $)	9 Months Ended			9 Months Ended				1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Revolving Credit Facility	Oct. 11, 2013 Revolving Credit Facility Subsequent Event	Sep. 30, 2013 Commercial Paper Minimum D	Sep. 30, 2013 Commercial Paper Maximum D	May 08, 2013 2.625% Notes Due May 8, 2013	Feb. 11, 2013 6.00% Senior Notes	Oct. 01, 2013 Notes One Subsequent Event	Oct. 01, 2013 Notes Two Subsequent Event
Debt Instrument [Line Items]
Commercial paper, Maturity period						3	114
Line of credit facility, maximum borrowing capacity					$ 4,500,000,000
Revolving credit facility debt covenant				24,600,000,000
Total shareholders' equity, excluding accumulated other comprehensive earnings / (losses)				35,700,000,000
Line of credit facility outstanding amount				0
Repayment of debt	1,750,000,000	4,336,000,000						1,000,000,000	750,000,000	1,000,000,000	800,000,000
Debt instrument, stated interest rate								2.625%	6.00%	5.125%	5.25%
Fair value of total debt	22,074,000,000		22,946,000,000
Carrying value of total debt	$ 19,919,000,000		$ 19,425,000,000