Summary of Significant Accounting Policies - Additional Information (Detail)	1 Months Ended		3 Months Ended
	Jul. 23, 2024 shares	Sep. 30, 2023 $ / shares shares	Mar. 31, 2025 USD ($) Location shares	Mar. 31, 2024 USD ($) shares	Dec. 31, 2024 USD ($)
Equity, Class of Treasury Stock [Line Items]
Number of locations | Location			79
Minimum number of shares that company is required to repurchase | shares	0
Amount of allowance for credit loss			$ 0	$ 0	$ 0
Shares repurchased and retired average price | $ / shares		$ 26.99
Minimum number of days to consider the loans as non-accrual			90 days	90 days
Impairment recorded			$ 0	$ 0
Other identifiable intangible assets, amortized period (years)			7 years
Securities sold under agreements to repurchase maturity range (in days)			one to four days
Interest-bearing time deposits, maturity period (in days)			90 days or less
Unrealized net losses in available-for-sale securities, included in accumulated other comprehensive income			$ 388,889,000	$ 441,227,000	424,289,000
First financial antidilutive securities excluded from eps computation | shares			368,000	417,000
Shares repurchased under stock repurchase authorization, shares | shares		101,337	0
Deferred Tax Assets			$ 106,228,000	$ 122,844,000	116,999,000
Commitments to Extend Credit [Member]
Equity, Class of Treasury Stock [Line Items]
Reserve for unfunded commitments			9,214,000	7,455,000	8,677,000
Held-to-maturity Securities [Member]
Equity, Class of Treasury Stock [Line Items]
Securities held to maturity			$ 0	$ 0	$ 0
Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, number of shares authorized to be repurchased | shares	5,000,000