Amount, before tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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Name:	us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Employee Benefits - Summary of Accumulated Other Comprehensive Loss Expected to be Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Amortization of loss to be recognized in 2020	$ 6,842	$ (3,770)	$ 2,315
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of loss to be recognized in 2020	1,041
Supplemental Insurance/ Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost to be recognized in 2020	114
Amortization of loss to be recognized in 2020	$ 849