Investment Securities - Proceeds from Sale, Gross Gains (Losses) Realized on Sales, Maturities and Other-Than-Temporary Impairment Charges Related to Securities Available for Sale (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net Investment Income [Line Items]
Proceeds from maturities and redemptions of available-for-sale securities	$ 33,756	$ 0
Gain Losses Maturities And Impairment	(103)	2
Sales
Net Investment Income [Line Items]
Gross Gains	0	0
Gross Losses	(103)	0
Gain Losses Maturities And Impairment	(103)	0
Maturities
Net Investment Income [Line Items]
Gross Gains	0	2
Gross Losses	0	0
Gain Losses Maturities And Impairment	$ 0	$ 2