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	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Net Investment Income [Line Items]
Proceeds from maturities and redemptions of available-for-sale securities	$ 0	$ 0
Gain Losses Maturities And Impairment	2	16
Sales
Net Investment Income [Line Items]
Gross Gains	0	0
Gross Losses	0	0
Gain Losses Maturities And Impairment	0	0
Maturities
Net Investment Income [Line Items]
Gross Gains	2	16
Gross Losses	0	0
Gain Losses Maturities And Impairment	$ 2	$ 16