LOANS, ALLOWANCE FOR LOAN LOSSES AND IMPAIRED LOANS - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Bank impaired loans
With no related allowance recorded, Recorded investment	$ 39,245	$ 59,065
With an allowance recorded, Recorded investment	4,152	4,131
Recorded investment, Total	43,397	63,196
With no related allowance recorded, unpaid principal balance	39,245	59,065
With an allowance recorded, unpaid principal balance	4,152	4,131
Unpaid principal balance, Total	43,397	63,196
Impaired Financing Receivable, Related Allowance	1,115	956
With no related allowance recorded, Average recorded investment	49,157	51,957
With an allowance recorded, Average recorded investment	4,143	3,308
Average recorded investment, Total	53,300	55,265
With no related allowance recorded, Interest income recognized	2,658	952
With an allowance recorded, Interest income recognized	177	22
Interest income recognized, Total	2,835	974
Commercial/Agricultural real estate:
Bank impaired loans
With no related allowance recorded, Recorded investment	24,013	40,514
With an allowance recorded, Recorded investment	2,290	2,143
Recorded investment, Total	26,303	42,657
With no related allowance recorded, unpaid principal balance	24,013	40,514
With an allowance recorded, unpaid principal balance	2,290	2,143
Unpaid principal balance, Total	26,303	42,657
Impaired Financing Receivable, Related Allowance	698	495
With no related allowance recorded, Average recorded investment	32,264	24,693
With an allowance recorded, Average recorded investment	2,217	1,738
Average recorded investment, Total	34,481	26,431
With no related allowance recorded, Interest income recognized	1,894	699
With an allowance recorded, Interest income recognized	100	4
Interest income recognized, Total	1,994	703
C&I/Agricultural operating:
Bank impaired loans
With no related allowance recorded, Recorded investment	6,334	9,477
With an allowance recorded, Recorded investment	781	490
Recorded investment, Total	7,115	9,967
With no related allowance recorded, unpaid principal balance	6,334	9,477
With an allowance recorded, unpaid principal balance	781	490
Unpaid principal balance, Total	7,115	9,967
Impaired Financing Receivable, Related Allowance	190	312
With no related allowance recorded, Average recorded investment	7,906	19,163
With an allowance recorded, Average recorded investment	636	734
Average recorded investment, Total	8,542	19,897
With no related allowance recorded, Interest income recognized	284	119
With an allowance recorded, Interest income recognized	22	3
Interest income recognized, Total	306	122
Residential mortgage:
Bank impaired loans
With no related allowance recorded, Recorded investment	8,542	8,695
With an allowance recorded, Recorded investment	1,079	1,431
Recorded investment, Total	9,621	10,126
With no related allowance recorded, unpaid principal balance	8,542	8,695
With an allowance recorded, unpaid principal balance	1,079	1,431
Unpaid principal balance, Total	9,621	10,126
Impaired Financing Receivable, Related Allowance	226	136
With no related allowance recorded, Average recorded investment	8,619	4,461
With an allowance recorded, Average recorded investment	1,255	789
Average recorded investment, Total	9,874	5,250
With no related allowance recorded, Interest income recognized	450	128
With an allowance recorded, Interest income recognized	54	15
Interest income recognized, Total	504	143
Consumer installment:
Bank impaired loans
With no related allowance recorded, Recorded investment	356	379
With an allowance recorded, Recorded investment	2	67
Recorded investment, Total	358	446
With no related allowance recorded, unpaid principal balance	356	379
With an allowance recorded, unpaid principal balance	2	67
Unpaid principal balance, Total	358	446
Impaired Financing Receivable, Related Allowance	1	13
With no related allowance recorded, Average recorded investment	368	3,640
With an allowance recorded, Average recorded investment	35	47
Average recorded investment, Total	403	3,687
With no related allowance recorded, Interest income recognized	30	6
With an allowance recorded, Interest income recognized	1	0
Interest income recognized, Total	$ 31	$ 6

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

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