INVESTMENT SECURITIES - Investments in Debt and Equity Securities Reported Less than Historical Cost (Details) - Investments reported at less than historical cost - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Historical cost	$ 1,629,698	$ 1,781,108
Fair value	1,437,973	1,560,554
Gross unrealized losses	$ 191,725	$ 220,554
Percentage of the Corporation's investment securities available for sale in an unrealized loss position	92.60%	95.90%