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Pension Plans and Other Postretirement Benefits - Schedule of Pension Plans with Projected and Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets (Detail) (USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2014
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Dec. 31, 2013
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|---|---|---|
| Projected Benefit Obligation Exceeds the Fair Value of Plan Assets | ||
| Projected benefit obligations | $ 280,091 | $ 237,914 |
| Fair value of plan assets | 92,570 | 81,347 |
| Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets | ||
| Accumulated benefit obligations | 177,496 | 152,056 |
| Fair value of plan assets | $ 44,382 | $ 50,004 |