LOANS - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	$ 343	$ 343
Nonaccrual Including 90 Days or More Past Due	4,609	4,369
Total Past Due and Nonaccrual	17,893	11,078
Current	3,736,310	3,661,518
Total Loans	3,754,203	3,672,596
Interest earned on non-accrual loans	0
Accrued interest on non-accrual loans	15
30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	9,097	4,465
60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	3,844	1,901
Commercial real estate occupied:
Past Due and Nonaccrual Loans
Total Loans		1,565,687
Commercial real estate occupied: | Mortgage loans | Owner
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	215	225
Total Past Due and Nonaccrual	801	1,575
Current	529,076	529,513
Total Loans	529,877	531,088
Commercial real estate occupied: | Mortgage loans | Owner | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	586	917
Commercial real estate occupied: | Mortgage loans | Owner | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	433
Commercial real estate occupied: | Mortgage loans | Non-owner
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	512	512
Total Past Due and Nonaccrual	1,886	610
Current	1,052,015	1,033,989
Total Loans	1,053,901	1,034,599
Commercial real estate occupied: | Mortgage loans | Non-owner | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	603	98
Commercial real estate occupied: | Mortgage loans | Non-owner | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	771	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	800,556	812,174
Total Loans	800,556	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	343	343
Nonaccrual Including 90 Days or More Past Due	2,433	2,743
Total Past Due and Nonaccrual	8,923	6,886
Current	476,569	486,258
Total Loans	485,492	493,144
Residential real estate | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	6,067	3,053
Residential real estate | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	80	747
Residential real estate | Mortgage loans
Past Due and Nonaccrual Loans
Total Loans	485,492	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	1,312	736
Total Past Due and Nonaccrual	4,657	1,730
Current	754,026	677,714
Total Loans	758,683	679,444
Commercial, industrial and agricultural | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,727	273
Commercial, industrial and agricultural | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,618	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	121	123
Total Past Due and Nonaccrual	1,491	123
Current	99,152	97,188
Total Loans	100,643	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	1,370	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	16	30
Total Past Due and Nonaccrual	135	154
Current	24,916	24,682
Total Loans	25,051	24,836
Installment/consumer loans | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	114	124
Installment/consumer loans | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	$ 5	$ 0