BASIS OF PRESENTATION - Impact of Adoption of the ASU (Details) - USD ($) $ in Thousands	Sep. 30, 2021		Jun. 30, 2021	Jan. 01, 2021	Dec. 31, 2020		Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326	$ 73,048	[1]	$ 71,713		$ 61,408
Valuation allowance before adoption of ASC 326					61,408	[1]	$ 60,747	$ 59,019	$ 50,652
ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				$ 61,408
Commercial and industrial loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326					28,333		28,363	26,744	25,789
Commercial and industrial loans | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				28,333
Commercial real estate and multi-family residential loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326					22,907		21,415	21,063	15,796
Commercial real estate and multi-family residential loans | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				22,907
Agri-business and agricultural loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326					3,043		3,097	3,408	3,869
Agri-business and agricultural loans | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				3,043
Other commercial loans | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				416
Consumer 1-4 family loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326					2,619		3,318	3,434	2,086
Consumer 1-4 family loans | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				2,619
Other consumer loans | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				951
Unallocated
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326	$ 380		$ 506		3,139
Valuation allowance before adoption of ASC 326					3,139		$ 3,152	$ 3,054	$ 2,320
Unallocated | ASU 2016-13 | Pre-ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance before adoption of ASC 326				3,139
As Reported Under ASC 326 | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				70,458
As Reported Under ASC 326 | Commercial and industrial loans | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				32,645
As Reported Under ASC 326 | Commercial real estate and multi-family residential loans | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				27,223
As Reported Under ASC 326 | Agri-business and agricultural loans | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				4,103
As Reported Under ASC 326 | Other commercial loans | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				1,357
As Reported Under ASC 326 | Consumer 1-4 family loans | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				3,572
As Reported Under ASC 326 | Other consumer loans | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				1,300
As Reported Under ASC 326 | Unallocated | As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				258
Impact of ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				9,050
Impact of ASC 326 Adoption | ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				9,100	9,050
Impact of ASC 326 Adoption | Commercial and industrial loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				4,312
Impact of ASC 326 Adoption | Commercial real estate and multi-family residential loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				4,316
Impact of ASC 326 Adoption | Agri-business and agricultural loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				1,060
Impact of ASC 326 Adoption | Other commercial loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				941
Impact of ASC 326 Adoption | Consumer 1-4 family loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				953
Impact of ASC 326 Adoption | Other consumer loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				349
Impact of ASC 326 Adoption | Unallocated
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326				$ (2,881)
Impact of ASC 326 Adoption | Unallocated | ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance after adoption of ASC 326					$ (2,881)

[1] Beginning January 1, 2021 calculation is based on the current expected credit loss methodology. Prior to January 1, 2021 calculation was based on the incurred loss methodology.