GOODWILL, CORE DEPOSIT PREMIUM AND OTHER INTANGIBLE ASSETS (Estimated future amortization expense for amortizable intangible assets) (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Future amortization expense for amortizable intangible assets [Line Items]
Three months ending December 31, 2021	$ 2,524
Year ending December 31,
2022	9,291
2023	8,080
2024	6,697
2025	5,614
2026	4,122
Thereafter	5,180
Total	41,508
Core Deposit Intangibles
Future amortization expense for amortizable intangible assets [Line Items]
Three months ending December 31, 2021	2,160
Year ending December 31,
2022	7,702
2023	6,739
2024	5,591
2025	4,700
2026	3,533
Thereafter	4,591
Total	35,016
Customer Relationship Intangibles
Future amortization expense for amortizable intangible assets [Line Items]
Three months ending December 31, 2021	9
Year ending December 31,
2022	34
2023	33
2024	33
2025	32
2026	0
Thereafter	0
Total	141
Mortgage Servicing Rights
Future amortization expense for amortizable intangible assets [Line Items]
Three months ending December 31, 2021	304
Year ending December 31,
2022	1,374
2023	1,178
2024	982
2025	785
2026	589
Thereafter	589
Total	5,801
Commercial Servicing Rights
Future amortization expense for amortizable intangible assets [Line Items]
Three months ending December 31, 2021	51
Year ending December 31,
2022	181
2023	130
2024	91
2025	97
2026	0
Thereafter	0
Total	$ 550

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Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in remainder of current fiscal year.

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 926
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959

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