Securities - Gross Unrealized Losses, Aggregated by Investment Category and Length of Time (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	$ (22)	$ (238)
Fair Value, Less Than Twelve Months	25,636	55,090
Gross Unrealized Losses, Twelve Months and Over		(142)
Fair Value, Twelve Months and Over		27,107
Gross Unrealized Losses, Total	(22)	(380)
Fair Value, Total	25,636	82,197
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Twelve Months and Over		(12)
Fair Value, Twelve Months and Over		5,030
Gross Unrealized Losses, Total		(12)
Fair Value, Total		5,030
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(16)	(16)
Fair Value, Less Than Twelve Months	18,593	10,549
Gross Unrealized Losses, Twelve Months and Over		(5)
Fair Value, Twelve Months and Over		10,745
Gross Unrealized Losses, Total	(16)	(21)
Fair Value, Total	18,593	21,294
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(4)	(102)
Fair Value, Less Than Twelve Months	6,254	27,696
Gross Unrealized Losses, Twelve Months and Over		(125)
Fair Value, Twelve Months and Over		11,332
Gross Unrealized Losses, Total	(4)	(227)
Fair Value, Total	6,254	39,028
State and Local Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(2)	(120)
Fair Value, Less Than Twelve Months	789	16,845
Gross Unrealized Losses, Total	(2)	(120)
Fair Value, Total	$ 789	$ 16,845