Directors Retirement Plan - Status of Directors Retirement Plan (Detail) - Director - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Accrued plan cost included in other liabilities	$ 646	$ 604
Recognized in accumulated other comprehensive income
Net actuarial loss (gain)	64	(29)
Unrecognized prior service cost	0	0
Amounts not recognized as a component of net postretirement benefit	$ 64	$ (29)

Amount, after 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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-SubTopic 10
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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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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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Amount, after tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation 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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