Retirement Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Employee service period under ESOP	1 year
Deferred compensation obligations	$ 7,923	$ 9,402
Cash values of the insurance policies purchased to fund deferred compensation obligations	117,823	117,318	$ 97,783
Unfunded status of the supplemental retirement plans	(11,193)	(4,802)
Deferred tax asset		1,420
Net actuarial loss	$ 2,984
401(k) Plan
Defined Benefit Plan Disclosure [Line Items]
Minimum age for employees	21 years
Minimum period for employees to participate	90 days
Discretionary matching contribution equal to percentage of participant's contribution	50.00%
Discretionary matching contribution maximum percentage of eligible compensation	4.00%
Supplemental Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Cash values of the insurance policies purchased to fund deferred compensation obligations	$ 117,823	117,318
Unfunded status of the supplemental retirement plans	11,193	4,802
Accumulated other comprehensive loss	7,884	$ 3,382
Deferred tax asset	$ 3,309

Change in net actuarial gain loss.

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Employee service period under ESOP.

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Minimum age for employee participation.

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Minimum service period for employees participation.

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- Definition

Amount of tax expense (benefit) allocated to accumulated other comprehensive income (loss) attributable to parent.

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- Definition

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

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Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

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Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount, after tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Percentage employer matches of the employee's percentage contribution matched.

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