GOODWILL AND OTHER INTANGIBLES - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Goodwill	$ 38,611,000	$ 38,611,000	$ 38,611,000	$ 38,632,000
Amortization of intangible assets	7,735,000	8,816,000	11,407,000
Change in carrying amount of goodwill	0	0
Merger and restructuring costs	$ 0	$ 0	$ 26,435,000
Goodwill Impaired Facts And Circumstances Leading To Impairment	The Corporation’s policy is to assess goodwill and other intangibles for impairment on an annual basis during the fourth quarter of each year, and more frequently if events or circumstances lead management to believe that the values of goodwill or other intangibles may be impaired. During the fourth quarter of 2023, management performed a qualitative analysis of the carrying amount of each relevant reporting units’ goodwill and concluded that it is more-likely-than-not that the fair value of the reporting units exceeded their carrying value, and thus no impairment charges for goodwill were recorded. This assessment involved identifying the inputs and assumptions that most affect fair value, including evaluating significant and relevant events impacting each reporting entity, and evaluating such factors to determine if a positive assertion can be made that it is more-likely-than-not that the fair value of the reporting units exceeded their carrying amount. In the qualitative assessment performed for each reporting unit, the Corporation evaluated events and circumstances that could impact the fair value including the following: ● Macroeconomic conditions, such as improvement or deterioration in general economic conditions; ● Industry and market considerations; ● Interest rate fluctuations; ● Overall financial performance of the reporting unit; ● Performance of industry peers over the last year; and ● Recent market transactions
Impaired Intangible Asset Description	. The Corporation amortizes core deposit intangibles based on the projected useful lives of the related deposits. Core deposit intangibles are analyzed annually for impairment, or sooner if events and circumstances indicate possible impairment. Factors that may suggest impairment include customer attrition and run-off. Management is unaware of any events and/or circumstances that would indicate a possible impairment to the core deposit intangibles as of December 31, 2023.