LOANS - Categorized by Internally Assigned Risk Grades (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loans by class categorized by internally assigned risk grades
Total loans	$ 4,653,647	$ 3,672,596
2020	1,405,317
2019	786,814
2018	369,895
2017	572,806
2016	315,542
2015 and prior	772,838
Revolving	404,401
Revolving Term	26,034
Total	4,653,647
Pass
Loans by class categorized by internally assigned risk grades
Total loans		3,584,290
Special Mention
Loans by class categorized by internally assigned risk grades
Total loans		47,003
Substandard
Loans by class categorized by internally assigned risk grades
Total loans		41,303
Commercial real estate occupied:
Loans by class categorized by internally assigned risk grades
Total loans		1,565,687
Commercial real estate occupied: | Owner occupied
Loans by class categorized by internally assigned risk grades
Total loans		531,088
Commercial real estate occupied: | Owner occupied | Pass
Loans by class categorized by internally assigned risk grades
Total loans		511,444
Commercial real estate occupied: | Owner occupied | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans		18,426
Commercial real estate occupied: | Owner occupied | Substandard
Loans by class categorized by internally assigned risk grades
Total loans		1,218
Commercial real estate occupied: | Non-owner occupied
Loans by class categorized by internally assigned risk grades
Total loans		1,034,599
Commercial real estate occupied: | Non-owner occupied | Pass
Loans by class categorized by internally assigned risk grades
Total loans		1,022,208
Commercial real estate occupied: | Non-owner occupied | Substandard
Loans by class categorized by internally assigned risk grades
Total loans		12,391
Commercial real estate occupied: | Mortgage loans | Owner occupied
Loans by class categorized by internally assigned risk grades
Total loans	532,597	531,088
2020	71,057
2019	92,983
2018	59,541
2017	89,033
2016	32,466
2015 and prior	187,517
Total	532,597
Commercial real estate occupied: | Mortgage loans | Owner occupied | Pass
Loans by class categorized by internally assigned risk grades
2020	69,830
2019	91,050
2018	48,771
2017	66,855
2016	25,485
2015 and prior	156,047
Total	458,038
Commercial real estate occupied: | Mortgage loans | Owner occupied | Watch
Loans by class categorized by internally assigned risk grades
2020	755
2019	1,380
2018	10,172
2017	10,809
2016	3,456
2015 and prior	27,372
Total	53,944
Commercial real estate occupied: | Mortgage loans | Owner occupied | Special Mention
Loans by class categorized by internally assigned risk grades
2019	553
2018	598
2017	10,918
2016	3,525
2015 and prior	3,837
Total	19,431
Commercial real estate occupied: | Mortgage loans | Owner occupied | Substandard
Loans by class categorized by internally assigned risk grades
2020	472
2017	451
2015 and prior	261
Total	1,184
Commercial real estate occupied: | Mortgage loans | Non-owner occupied
Loans by class categorized by internally assigned risk grades
Total loans	1,097,290	1,034,599
2020	157,527
2019	261,687
2018	123,244
2017	205,725
2016	73,844
2015 and prior	275,263
Total	1,097,290
Commercial real estate occupied: | Mortgage loans | Non-owner occupied | Pass
Loans by class categorized by internally assigned risk grades
2020	152,235
2019	253,987
2018	120,314
2017	185,936
2016	55,868
2015 and prior	240,773
Total	1,009,113
Commercial real estate occupied: | Mortgage loans | Non-owner occupied | Watch
Loans by class categorized by internally assigned risk grades
2020	5,292
2019	7,700
2018	2,930
2017	10,783
2016	17,976
2015 and prior	33,128
Total	77,809
Commercial real estate occupied: | Mortgage loans | Non-owner occupied | Special Mention
Loans by class categorized by internally assigned risk grades
2015 and prior	290
Total	290
Commercial real estate occupied: | Mortgage loans | Non-owner occupied | Substandard
Loans by class categorized by internally assigned risk grades
2017	9,006
2015 and prior	1,072
Total	10,078
Multi-family
Loans by class categorized by internally assigned risk grades
Total loans		812,174
2020	106,693
2019	297,329
2018	40,993
2017	122,965
2016	158,702
2015 and prior	126,581
Total	853,263
Multi-family | Pass
Loans by class categorized by internally assigned risk grades
Total loans		811,770
2020	106,693
2019	294,605
2018	40,993
2017	99,331
2016	134,851
2015 and prior	113,283
Total	789,756
Multi-family | Watch
Loans by class categorized by internally assigned risk grades
2019	2,724
2017	23,634
2016	23,851
2015 and prior	12,906
Total	63,115
Multi-family | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans		404
2015 and prior	392
Total	392
Multi-family | Mortgage loans
Loans by class categorized by internally assigned risk grades
Total loans	853,263	812,174
Residential real estate
Loans by class categorized by internally assigned risk grades
Total loans	449,984	493,144
2020	15,706
2019	33,609
2018	78,380
2017	100,898
2016	27,746
2015 and prior	130,433
Revolving	52,549
Revolving Term	10,663
Total	449,984
Residential real estate | Pass
Loans by class categorized by internally assigned risk grades
Total loans		475,949
2020	15,706
2019	32,035
2018	76,905
2017	100,094
2016	27,184
2015 and prior	116,745
Revolving	51,751
Revolving Term	7,800
Total	428,220
Residential real estate | Watch
Loans by class categorized by internally assigned risk grades
2019	466
2018	408
2017	323
2016	562
2015 and prior	1,751
Revolving Term	1,281
Total	4,791
Residential real estate | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans		12,400
2019	1,108
2018	762
2015 and prior	5,722
Revolving	798
Revolving Term	718
Total	9,108
Residential real estate | Substandard
Loans by class categorized by internally assigned risk grades
Total loans		4,795
2018	305
2017	481
2015 and prior	6,215
Revolving Term	864
Total	7,865
Residential real estate | Mortgage loans
Loans by class categorized by internally assigned risk grades
Total loans	449,984	493,144
Commercial, industrial and agricultural
Loans by class categorized by internally assigned risk grades
Total loans	1,631,167	679,444
2020	1,034,229
2019	76,732
2018	58,228
2017	41,113
2016	22,783
2015 and prior	50,020
Revolving	334,202
Revolving Term	13,860
Total	1,631,167
Commercial, industrial and agricultural | Pass
Loans by class categorized by internally assigned risk grades
Total loans		643,413
2020	1,025,066
2019	73,283
2018	39,742
2017	33,565
2016	21,057
2015 and prior	36,261
Revolving	279,990
Revolving Term	5,898
Total	1,514,862
Commercial, industrial and agricultural | Watch
Loans by class categorized by internally assigned risk grades
2020	8,513
2019	2,926
2018	12,960
2017	3,018
2016	1,199
2015 and prior	3,541
Revolving	39,957
Revolving Term	1,568
Total	73,682
Commercial, industrial and agricultural | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans		15,670
2020	650
2019	523
2018	759
2017	771
2016	56
2015 and prior	764
Revolving	14,055
Revolving Term	2,825
Total	20,403
Commercial, industrial and agricultural | Substandard
Loans by class categorized by internally assigned risk grades
Total loans		20,361
2018	4,767
2017	3,759
2016	471
2015 and prior	9,454
Revolving	200
Revolving Term	3,569
Total	22,220
Real estate construction and land loans
Loans by class categorized by internally assigned risk grades
Total loans	66,826	97,311
2020	18,833
2019	23,547
2018	9,320
2017	12,957
2015 and prior	2,169
Total	66,826
Real estate construction and land loans | Pass
Loans by class categorized by internally assigned risk grades
Total loans		95,530
2020	18,833
2019	23,547
2018	8,242
2017	11,406
2015 and prior	1,778
Total	63,806
Real estate construction and land loans | Watch
Loans by class categorized by internally assigned risk grades
2017	1,551
2015 and prior	274
Total	1,825
Real estate construction and land loans | Special Mention
Loans by class categorized by internally assigned risk grades
2018	1,078
Total	1,078
Real estate construction and land loans | Substandard
Loans by class categorized by internally assigned risk grades
Total loans		1,781
2015 and prior	117
Total	117
Installment/consumer loans
Loans by class categorized by internally assigned risk grades
Total loans	22,520	24,836
2020	1,272
2019	927
2018	189
2017	115
2016	1
2015 and prior	855
Revolving	17,650
Revolving Term	1,511
Total	22,520
Installment/consumer loans | Pass
Loans by class categorized by internally assigned risk grades
Total loans		23,976
2020	1,272
2019	927
2018	189
2017	111
2016	1
2015 and prior	855
Revolving	17,600
Revolving Term	550
Total	21,505
Installment/consumer loans | Watch
Loans by class categorized by internally assigned risk grades
Revolving Term	41
Total	41
Installment/consumer loans | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans		103
Revolving Term	100
Total	100
Installment/consumer loans | Substandard
Loans by class categorized by internally assigned risk grades
Total loans		$ 757
2017	4
Revolving	50
Revolving Term	820
Total	$ 874