Benefit Plans - Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets for Non-Qualified Plans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 175,405	$ 157,364	$ 170,566
Accumulated benefit obligation	175,405	157,364
Fair value of plan assets	236,621	210,508	$ 222,124
Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	20,081	18,708
Accumulated benefit obligation	20,081	18,708
Fair value of plan assets	$ 0	$ 0

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

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