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Pension and Other Postretirement Benefit Plans - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | ||||
|---|---|---|---|---|---|
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Dec. 31, 2013
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Mar. 31, 2014
Defined Benefit Pension Plan [Member]
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Mar. 31, 2014
Other Benefits [Member]
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Mar. 31, 2014
Legacy Pension Plan (LPP) [Member]
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Mar. 31, 2013
Legacy Pension Plan (LPP) [Member]
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| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||||
| Amendment description in retiree medical benefits | In February 2009, we amended our retiree medical plan to reduce the subsidies received by participants by 20% per year over five years, with no further subsidies beginning January 1, 2014. | ||||
| Prior service cost recorded in other comprehensive income | $ 57 | ||||
| Employer's contribution to pension plan | $ 11 | $ 0 | $ 0 | ||