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Weighted-Average Assumptions used to Determine Benefit Obligations (Detail)
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Dec. 31, 2011
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Dec. 31, 2010
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Pension Benefits
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| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 4.60% | 5.24% |
| Rate of compensation increase | 4.41% | 4.37% |
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Other Benefits
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| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 4.29% | 4.90% |
| X | ||||||||||
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- Definition
The interest rate used to adjust for the time value of money for the plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Expected rate of compensation increases (for pay-related plans). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Details
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