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ACQUISITIONS - Intangible Asset, Goodwill and Acquisition-related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Summary of loans acquired [Abstract]
Merger and acquisition integration related (recoveries) expenses	$ 102	$ 796	$ 133	$ 4,537
Steuben Trust Corporation [Member] | Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible asset useful life (amortization period)			8 years
NuVantage Insurance Corporation [Member] | Core deposit intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible asset useful life (amortization period)			8 years
Fringe Benefits Design of Minnesota, Inc ("FBD") [Member] | Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible asset useful life (amortization period)			15 years
Thomas Gregory Associates [Member] | Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible asset useful life (amortization period)			13 years

X

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=123586518&loc=d3e1043-128460

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- References

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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