| Fair Values of Derivative Assets and Liabilities by Hedge Type (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2011 | Dec. 31, 2010 | 
|---|---|---|
| Asset Derivatives | ||
| Total Asset Derivatives | $ 649 | $ 218 | 
| Liability Derivatives | ||
| Total Liability Derivatives | 208 | 141 | 
| Foreign exchange contracts | ||
| Asset Derivatives | ||
| Total Asset Derivatives | 166 | 36 | 
| Liability Derivatives | ||
| Total Liability Derivatives | 185 | 111 | 
| Interest rate contracts | ||
| Asset Derivatives | ||
| Total Asset Derivatives | 483 | 182 | 
| Liability Derivatives | ||
| Total Liability Derivatives | 23 | 30 | 
| Fair Value, Inputs, Level 2 | ||
| Asset Derivatives | ||
| Total Asset Derivatives | 649 | 218 | 
| Liability Derivatives | ||
| Total Liability Derivatives | 208 | 141 | 
| Fair Value, Inputs, Level 2 | Foreign exchange contracts | ||
| Asset Derivatives | ||
| Total Asset Derivatives | 166 | 36 | 
| Liability Derivatives | ||
| Total Liability Derivatives | 185 | 111 | 
| Fair Value, Inputs, Level 2 | Interest rate contracts | ||
| Asset Derivatives | ||
| Total Asset Derivatives | 483 | 182 | 
| Liability Derivatives | ||
| Total Liability Derivatives | $ 23 | $ 30 | 
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- Definition Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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