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ACQUISITIONS (Details) $ in Thousands							3 Months Ended
ACQUISITIONS (Details) $ in Thousands	May 01, 2023 USD ($)	Mar. 01, 2023 USD ($)	Nov. 01, 2022 USD ($)	May 13, 2022 USD ($) country	Jan. 01, 2022 USD ($)	Jan. 01, 2021 Agency	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Acquisitions
Goodwill							$ 842,936	$ 799,080	$ 841,841
Loans							0		436,954
Investment securities							0		11,305
Deposits							0		522,295
Number of insurance agencies asset acquired \| Agency						3
Net increase (decrease) in goodwill							1,095
Core Deposit Intangibles
Acquisitions
Deposits							0		(7,970)
Subsequent events \| Certain assets of Hyde Park Insurance Services, Inc.
Acquisitions
Cash consideration	$ 4,300
Axiom
Acquisitions
Cash consideration		$ 1,800
Intangibles		500
Goodwill		$ 1,300					1,270
Revenue							100
Operating Expenses							200
Loans							0
Investment securities							0
Deposits							0
Direct expenses							200
Axiom \| Core Deposit Intangibles
Acquisitions
Deposits							0
Certain Assets Of Jmd Associates
Acquisitions
Cash consideration			$ 1,000
Goodwill			500
Revenue							100
Operating Expenses							100
Direct expenses							100
Certain Assets Of Jmd Associates \| Noncompete agreement
Acquisitions
Intangibles			100
Certain Assets Of Jmd Associates \| Customer list intangible
Acquisitions
Intangibles			$ 400
Elmira Savings Bank ("Elmira")
Acquisitions
Goodwill				$ 41,900					41,926
Revenue							4,700
Operating Expenses							1,100
Purchase price of acquisition				$ 82,200
Number of country \| country				5
Assets acquired				$ 583,700
Loans				437,000					436,954
Investment securities				11,300					11,305
Deposits				522,300					522,295
Direct expenses							1,100
Elmira Savings Bank ("Elmira") \| Core Deposit Intangibles
Acquisitions
Deposits				$ 8,000					$ (7,970)
Fringe Benefits Design of Minnesota, Inc ("FBD")
Acquisitions
Net increase (decrease) in goodwill							300
One Group NY, Inc.
Acquisitions
Intangibles					$ 2,500
Revenue							200	300
Operating Expenses							100	100
Purchase price of acquisition					$ 2,500
Direct expenses							$ 100	$ 100