Employee Benefit Plans - Estimated Amounts Amortized from Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Actuarial loss	$ 84,572
Prior service credit	(7,598)
Total	76,974
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Actuarial loss	1,124
Prior service credit	(956)
Total	$ 168

The amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are 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.

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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.

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- Definition

The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented, including the net gain (loss), net prior service cost or credit, and net transition asset or obligation.

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