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Components of Net Periodic Benefit Cost (Detail) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
|
Sep. 30, 2012
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Sep. 30, 2011
|
Sep. 30, 2012
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Sep. 30, 2011
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Pension Benefits
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| Defined Benefit Plan Disclosure [Line Items] | ||||
| Interest cost | $ 1,475 | $ 1,871 | $ 4,425 | $ 5,613 |
| Expected return on plan assets | (2,225) | (2,342) | (6,675) | (7,025) |
| Amortization of Unrecognized actuarial (gain) loss | 575 | 896 | (275) | 2,687 |
| Net periodic benefit cost (income) | (175) | 425 | (2,525) | 1,275 |
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Other Benefits
|
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| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 199 | 161 | 598 | 482 |
| Interest cost | 452 | 387 | 1,354 | 1,162 |
| Expected return on plan assets | (8) | (9) | (24) | (28) |
| Amortization of Unrecognized actuarial (gain) loss | 70 | 4 | 211 | 13 |
| Amortization of Unrecognized prior service cost | (63) | (68) | (189) | (204) |
| Net periodic benefit cost (income) | $ 650 | $ 475 | $ 1,950 | $ 1,425 |