Schedule of Reconciliation of Defined Benefit Pension Plan (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 106,469	$ 104,074
Actual return (loss) on plan assets	16,470	8,037
Employer contributions	0	0
Benefits paid	(5,605)us-gaap_DefinedBenefitPlanBenefitsPaid	(5,042)us-gaap_DefinedBenefitPlanBenefitsPaid
Administrative expenses	(637)	(600)
Fair value of plan assets at end of year	116,697	106,469	104,074
Benefit obligation at beginning of year	103,558	114,529
Service cost	966us-gaap_DefinedBenefitPlanServiceCost	1,060us-gaap_DefinedBenefitPlanServiceCost	1,144us-gaap_DefinedBenefitPlanServiceCost
Interest cost	4,986us-gaap_DefinedBenefitPlanInterestCost	4,528us-gaap_DefinedBenefitPlanInterestCost
Benefits paid	(5,605)	(5,042)
Actuarial (gain) loss	23,437	(11,517)
Benefit obligation at end of year	127,342	103,558	114,529
Other non-current assets	0	2,911
Other non-current liabilities	10,645	0
Total amounts recognized at end of year	$ 10,645	$ 2,911

Defined Benefit Plan, Administrative Expenses

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Defined Benefit Plan, Benefit Obligation, Benefits Paid

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The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

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-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)

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Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

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The aggregate net amount recognized in the balance sheet associated with the defined benefit plan(s). Will normally be the same as the Defined Benefit Plan, Funded Status of Plan, Total.

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The amount for overfunded plans recognized in the balance sheet as a noncurrent asset associated with a defined benefit pension plan or other postretirement defined benefit plan.

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1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

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The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

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The increase in the fair value of plan assets from contributions made by the employer.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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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.

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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.

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This represents the noncurrent liability for underfunded plans recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement defined benefit plans.

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