LOANS - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	$ 0	$ 343
Nonaccrual Including 90 Days or More Past Due	7,064	4,369
Total Past Due and Nonaccrual	17,746	11,078
Current	4,635,901	3,661,518
Total Loans	4,653,647	3,672,596
Interest earned on non-accrual loans	0
Accrued interest on non-accrual loans	151
30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	8,551	4,465
60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	2,131	1,901
Commercial real estate occupied:
Past Due and Nonaccrual Loans
Total Loans		1,565,687
Commercial real estate occupied: | Owner occupied
Past Due and Nonaccrual Loans
Total Loans		531,088
Commercial real estate occupied: | Non-owner occupied
Past Due and Nonaccrual Loans
Total Loans		1,034,599
Commercial real estate occupied: | Mortgage loans | Owner occupied
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	1,653	225
Total Past Due and Nonaccrual	3,120	1,575
Current	529,477	529,513
Total Loans	532,597	531,088
Commercial real estate occupied: | Mortgage loans | Owner occupied | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	442	917
Commercial real estate occupied: | Mortgage loans | Owner occupied | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,025	433
Commercial real estate occupied: | Mortgage loans | Non-owner occupied
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	746	512
Total Past Due and Nonaccrual	760	610
Current	1,096,530	1,033,989
Total Loans	1,097,290	1,034,599
Commercial real estate occupied: | Mortgage loans | Non-owner occupied | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	98
Commercial real estate occupied: | Mortgage loans | Non-owner occupied | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	14	0
Multi-family
Past Due and Nonaccrual Loans
Total Loans		812,174
Multi-family | Mortgage loans
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	0	0
Total Past Due and Nonaccrual	0	0
Current	853,263	812,174
Total Loans	853,263	812,174
Multi-family | Mortgage loans | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	0
Multi-family | Mortgage loans | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	0
Residential real estate
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	343
Nonaccrual Including 90 Days or More Past Due	3,032	2,743
Total Past Due and Nonaccrual	8,601	6,886
Current	441,383	486,258
Total Loans	449,984	493,144
Residential real estate | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	5,220	3,053
Residential real estate | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	349	747
Residential real estate | Mortgage loans
Past Due and Nonaccrual Loans
Total Loans	449,984	493,144
Commercial, industrial and agricultural
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	1,506	736
Total Past Due and Nonaccrual	5,037	1,730
Current	1,626,130	677,714
Total Loans	1,631,167	679,444
Commercial, industrial and agricultural | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	2,788	273
Commercial, industrial and agricultural | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	743	721
Real estate construction and land loans
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	117	123
Total Past Due and Nonaccrual	117	123
Current	66,709	97,188
Total Loans	66,826	97,311
Real estate construction and land loans | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	0
Real estate construction and land loans | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	0
Installment/consumer loans
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	10	30
Total Past Due and Nonaccrual	111	154
Current	22,409	24,682
Total Loans	22,520	24,836
Installment/consumer loans | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	101	124
Installment/consumer loans | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	$ 0	$ 0