Comprehensive Income - Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, net of tax	$ 981	$ 12,280
Net unrealized gain (loss) on available for sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before tax, attributable to parent	(392)	19,183
Tax effect	116	(5,671)
Accumulated other comprehensive income, net of tax	(276)	13,512
Unfunded status of the supplemental retirement plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before tax, attributable to parent	2,399	(1,294)
Tax effect	(709)	382
Accumulated other comprehensive income, net of tax	1,690	(912)
Joint beneficiary agreement liability, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before tax, attributable to parent	$ (433)	$ (320)