Employee Benefit Plans (Combined Activity in Corporations Defined Benefit Pension Plans) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Benefit obligation at beginning of year	$ 163,876	$ 178,158	$ 157,855
Interest cost	8,002us-gaap_DefinedBenefitPlanInterestCost	7,341us-gaap_DefinedBenefitPlanInterestCost	7,801us-gaap_DefinedBenefitPlanInterestCost
Actuarial (gain) loss	34,438	(15,333)	18,436
Benefits paid	(6,679)us-gaap_DefinedBenefitPlanBenefitsPaid	(6,290)us-gaap_DefinedBenefitPlanBenefitsPaid	(5,934)us-gaap_DefinedBenefitPlanBenefitsPaid
Benefit obligation at end of year	199,637	163,876	178,158
Fair value of plan assets at beginning of year	164,769	145,901	137,253
Actual return on plan assets	9,428	24,489	13,931
Employer contributions	667	669	651
Benefits paid	(6,679)us-gaap_DefinedBenefitPlanBenefitsPaid	(6,290)us-gaap_DefinedBenefitPlanBenefitsPaid	(5,934)us-gaap_DefinedBenefitPlanBenefitsPaid
Fair value of plan assets at end of year	168,185	164,769	145,901
Funded status of the plan at end of year and accrued (benefit) liability recognized	31,452	(893)	32,257
Accumulated benefit obligation at end of year	$ 199,637	$ 163,876	$ 178,158

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For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Benefit Obligation

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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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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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This represents the entire liability recognized in the balance sheet that is associated with the defined benefit plans.

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