|
Effect of One-Percentage Point Change in Assumed Healthcare Cost Trend Rates (Detail) (USD $)
In Millions, unless otherwise specified |
12 Months Ended |
|---|---|
|
Dec. 31, 2011
|
|
| Defined Benefit Plan Disclosure [Line Items] | |
| Effect of 1-percentage point increase on total service and interest cost components | $ 0.2 |
| Effect of 1-percentage point increase on accumulated postretirement benefit obligation | 3.0 |
| Effect of 1-percentage point decrease on total service and interest cost components | (0.2) |
| Effect of 1-percentage point decrease on accumulated postretirement benefit obligation | $ (2.6) |
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
The effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The effect of a one-percentage- point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|