Retirement Plan, Based on Measurement Date (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in Plan Assets:
Fair value of assets at end of year	$ 242,558
Pension Benefits
Change in Benefit Obligation:
Benefit obligation at beginning of year	143,235	$ 151,411
Interest cost	5,660	5,085	$ 5,616
Actuarial loss (gain)	18,806	(4,676)
Annuity payments	(6,473)	(6,453)
Settlements	(1,332)	(2,132)
Benefit obligation at end of year	159,896	143,235	151,411
Change in Plan Assets:
Fair value of assets at beginning of year	210,246	234,136
Actual return (loss) on plan assets	40,117	(15,305)
Annuity payments	(6,473)	(6,453)
Settlements	(1,332)	(2,132)
Fair value of assets at end of year	242,558	210,246	$ 234,136
Funded status (included in "Other assets")	82,662	67,011
Changes recognized in other comprehensive income for the year ended December 31:
Amortization of actuarial loss	(10,035)	(7,179)
Net actuarial (gain) loss arising during the year	(7,378)	26,768
Total recognized in other comprehensive income for the year (pre-tax)	(17,413)	19,589
Accumulated other comprehensive loss (pre-tax) not yet recognized in net periodic benefit cost at December 31:
Actuarial loss, net	75,767	93,180
Total accumulated other comprehensive loss (pre-tax)	$ 75,767	$ 93,180

Other Comprehensive Income, Amortization of Net Actuarial Gain (Loss), Before Tax

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Amount, before 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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