COMMITMENTS AND CONTINGENT LIABILITIES - Legal Proceeding and Other Contingent Liabilities (Details) - USD ($)									3 Months Ended				6 Months Ended		12 Months Ended
	Nov. 15, 2023	Apr. 26, 2023	Apr. 13, 2023	Feb. 16, 2023	Dec. 01, 2020	Aug. 31, 2020	Feb. 04, 2020	Aug. 30, 2019	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2024	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	May 14, 2021	Apr. 30, 2020
COMMITMENTS AND CONTINGENT LIABILITIES
Litigation-related expense													$ 0	$ 0	$ 0	$ 0
Deposit activity, the Bank's potential exposure for fraudulent activity											$ 18,500,000
Amount set off											16,000,000
Another bank returning/ calling back								$ 15,600,000
Non-interest expense associated with potentially fraudulent activity											2,500,000
Additional charges on non interest expense													0
Lending activity, the Bank's potential exposure for fraudulent activity											15,800,000
Amount of commercial loan relationships with a customer for which the Bank is the originating lender and which there is potentially fraudulent activity											$ 35,800,000
Provision for loan losses related to charge-off the entire principal balance owed to the Bank related to the customer's commercial loan relationship as it relates to the potentially fraudulent activity												$ 15,800,000
Partial recovery recognized related to the charge-off of the Mann Entities commercial loan relationships									$ 34,000	$ 1,700,000
Additional charge on provision for loan losses													0
Additional recoveries on charge off of loans													0
Insurance recoveries related to partial reimbursement of defense costs													0	$ 1,200,000	$ 1,200,000	$ 3,700,000
Bank's Interest in cash and securities forfeited by Michael Mann, in which Bank filed petition to adjudicate the validity of the security interest in the forfeited property																	$ 14,900,000
Southwestern third amended complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, compensatory damages sought, minimum, by plaintiff		$ 13,000,000
Natpay amended complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, compensatory damages sought, minimum, by plaintiff			$ 3,800,000
Cachet financial services amended complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff				$ 25,600,000
Alleged amount stolen per Cachet complaint				26,400,000
Portion of alleged stolen funds Bank is holding per assertion made by Cachet				8,500,000
Assertion made by a third party of the amount of actual damages				$ 8,500,000
Berkshire bank complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff							$ 15,600,000
Chemung canal trust company complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff							$ 4,200,000
DOJ complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Value of funds in a third party account, claimed to be wrongfully seized by the Company and Bank to apply towards debts allegedly owed to the Bank																		$ 7,300,000
AXH complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff						$ 336,000
TBC complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Payment made to plaintiff pursuant to settlement agreement	$ 5,950,000
Minimum
COMMITMENTS AND CONTINGENT LIABILITIES
Loss contingency, estimate of possible loss													0
Minimum | Southwestern third amended complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff		$ 39,000,000
Minimum | Natpay amended complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff			$ 11,400,000
Minimum | TBC complaint
COMMITMENTS AND CONTINGENT LIABILITIES
Complaint, damages sought by plaintiff					$ 34,100,000
Maximum
COMMITMENTS AND CONTINGENT LIABILITIES
Loss contingency, estimate of possible loss													$ 54,400,000