Securities - Gross Unrealized Losses, Aggregated by Investment Category and Length of Time (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	$ (19,970)	$ (4,842)
Fair Value, Less Than Twelve Months	241,627	256,800
Gross Unrealized Losses, Twelve Months and Over	(19,685)	(2,221)
Fair Value, Twelve Months and Over	148,312	63,659
Gross Unrealized Losses, Total	(39,655)	(7,063)
Fair Value, Total	389,939	320,459
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(5,170)	(1,598)
Fair Value, Less Than Twelve Months	71,736	89,177
Gross Unrealized Losses, Twelve Months and Over	(3,165)
Fair Value, Twelve Months and Over	6,774
Gross Unrealized Losses, Total	(8,335)	(1,598)
Fair Value, Total	78,510	89,177
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(4,305)	(1,898)
Fair Value, Less Than Twelve Months	55,400	86,739
Gross Unrealized Losses, Twelve Months and Over	(9,672)	(1,584)
Fair Value, Twelve Months and Over	102,702	41,738
Gross Unrealized Losses, Total	(13,977)	(3,482)
Fair Value, Total	158,102	128,477
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(6,432)	(1,050)
Fair Value, Less Than Twelve Months	61,720	63,157
Gross Unrealized Losses, Twelve Months and Over	(5,581)	(412)
Fair Value, Twelve Months and Over	32,261	16,434
Gross Unrealized Losses, Total	(12,013)	(1,462)
Fair Value, Total	93,981	79,591
State and Local Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(4,063)	(296)
Fair Value, Less Than Twelve Months	52,771	17,727
Gross Unrealized Losses, Twelve Months and Over	(1,267)	(225)
Fair Value, Twelve Months and Over	6,575	5,487
Gross Unrealized Losses, Total	(5,330)	(521)
Fair Value, Total	$ 59,346	$ 23,214

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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