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Components of Net Periodic Benefit Cost (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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Dec. 31, 2009
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Pension Benefits
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| Defined Benefit Plan Disclosure [Line Items] | |||
| Service cost | $ 6.4 | $ 6.4 | $ 5.3 |
| Interest cost | 34.5 | 34.9 | 35.1 |
| Expected return on plan assets | (46.6) | (44.8) | (44.8) |
| Amortization of prior service cost | 0.8 | 0.8 | 0.8 |
| Recognized actuarial loss | 12.0 | 9.2 | 8.7 |
| Special termination benefit | 0.1 | ||
| Total net periodic benefit cost | 7.1 | 6.5 | 5.2 |
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Other Benefits
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| Defined Benefit Plan Disclosure [Line Items] | |||
| Service cost | 0.6 | 0.5 | 0.5 |
| Interest cost | 1.6 | 1.7 | 1.8 |
| Expected return on plan assets | (1.7) | (1.5) | (1.5) |
| Amortization of prior service cost | (0.2) | (0.2) | (0.2) |
| Recognized actuarial loss | 1.3 | 1.2 | 1.1 |
| Total net periodic benefit cost | $ 1.6 | $ 1.7 | $ 1.7 |
| X | ||||||||||
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- Definition
The amount of gains or losses recognized in net periodic benefit cost. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amounts in accumulated other comprehensive income related to prior service cost or credit expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of increase related to special termination benefits offered to and accepted by employees in connection with their termination of employment that are only offered for a short period of time. A situation involving termination benefits may also involve a curtailment. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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