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Pension Plans and Other Postretirement Benefits - Schedule of Estimated Future Benefit Payments, Reflecting Expected Future Service (Detail) (USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2014
|
|---|---|
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |
| 2015 | $ 3,707 |
| 2016 | 4,298 |
| 2017 | 4,547 |
| 2018 | 5,014 |
| 2019 | 5,046 |
| 2020 through 2024 | 38,399 |
| Total | 61,011 |
| Defined Benefit Pension Plans [Member] | |
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |
| 2015 | 3,635 |
| 2016 | 4,193 |
| 2017 | 4,402 |
| 2018 | 4,819 |
| 2019 | 4,786 |
| 2020 through 2024 | 35,747 |
| Total | 57,582 |
| Other Postretirement Benefit Plans [Member] | |
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |
| 2015 | 72 |
| 2016 | 105 |
| 2017 | 145 |
| 2018 | 195 |
| 2019 | 260 |
| 2020 through 2024 | 2,652 |
| Total | 3,429 |
| Supplemental Employee Retirement Plan [Member] | |
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |
| 2017 | 13,562 |
| Total | $ 13,562 |