Retirement Plans - Funded Status and Accrued Pension Cost (Detail) (Pension Plan [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Plan [Member]
CHANGE IN BENEFIT OBLIGATION:
Benefit obligation at beginning of year	$ 80,901	$ 96,384
Interest cost	3,577	3,376	3,655
Actuarial (gain) loss	14,458	(11,560)
Benefits paid	(4,823)	(7,299)
Benefit obligation at end of year	94,113	80,901	96,384
CHANGE IN PLAN ASSETS:
Fair value of plan assets at beginning of year	74,976	69,611
Actual return on plan assets	3,238	11,044
Employer contributions	1,869	1,620
Benefits paid	(4,823)	(7,299)
Fair value of plan assets at end of year	75,260	74,976	69,611
Funded status and accrued pension cost	$ (18,853)	$ (5,925)

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-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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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 funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

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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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