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Inventories - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
12 Months Ended | |
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Dec. 31, 2011
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Dec. 31, 2010
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| Inventories [Line Items] | ||
| Inventories valued on the LIFO basis | $ 3,387 | $ 4,051 |
| Excess of current replacement cost over LIFO cost of inventories | 8,400 | 6,800 |
| Effect of LIFO inventory liquidation on income | 160 | |
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R&M [Member]
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| Inventories [Line Items] | ||
| Effect of LIFO inventory liquidation on income | $ 155 |
| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
The effect of liquidating LIFO (last in first out) inventory layers on income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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