LOANS - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	$ 318	$ 308
Nonaccrual Including 90 Days or More Past Due	3,071	2,808
Total Past Due and Nonaccrual	21,326	7,516
Current	3,362,388	3,261,256
Total Loans	3,383,714	3,268,772
30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	7,639	3,780
60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	10,298	620
Commercial Real Estate | Mortgage loans
Past Due and Nonaccrual Loans
Total Loans	1,402,633	1,373,556
Commercial Real Estate | 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	580	253
Total Past Due and Nonaccrual	1,770	780
Current	541,066	509,618
Total Loans	542,836	510,398
Commercial Real Estate | Mortgage loans | Owner occupied | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,190	333
Commercial Real Estate | Mortgage loans | Owner occupied | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	194
Commercial Real Estate | 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	878	885
Total Past Due and Nonaccrual	10,170	885
Current	849,627	862,273
Total Loans	859,797	863,158
Commercial Real Estate | Mortgage loans | Non-owner occupied | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	0
Commercial Real Estate | Mortgage loans | Non-owner occupied | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	9,292	0
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	624,114	585,827
Total Loans	624,114	585,827
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 mortgage loans | Mortgage loans
Past Due and Nonaccrual Loans
Total Loans	515,173	519,763
Residential real estate mortgage loans | Mortgage loans | Residential mortgage
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	422	199
Total Past Due and Nonaccrual	2,356	1,321
Current	444,193	447,194
Total Loans	446,549	448,515
Residential real estate mortgage loans | Mortgage loans | Residential mortgage | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,934	892
Residential real estate mortgage loans | Mortgage loans | Residential mortgage | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	230
Residential real estate mortgage loans | Mortgage loans | Home equity
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	318	308
Nonaccrual Including 90 Days or More Past Due	622	624
Total Past Due and Nonaccrual	1,957	1,965
Current	66,667	69,283
Total Loans	68,624	71,248
Residential real estate mortgage loans | Mortgage loans | Home equity | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,017	1,033
Residential real estate mortgage loans | Mortgage loans | Home equity | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	0
Commercial, industrial and agricultural loans
Past Due and Nonaccrual Loans
Total Loans	671,897	645,724
Commercial, industrial and agricultural loans | Secured
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	197	174
Total Past Due and Nonaccrual	1,384	700
Current	162,254	167,840
Total Loans	163,638	168,540
Commercial, industrial and agricultural loans | Secured | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,137	330
Commercial, industrial and agricultural loans | Secured | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	50	196
Commercial, industrial and agricultural loans | Unsecured
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	0	0
Nonaccrual Including 90 Days or More Past Due	342	621
Total Past Due and Nonaccrual	3,659	1,729
Current	504,600	475,455
Total Loans	508,259	477,184
Commercial, industrial and agricultural loans | Unsecured | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	2,361	1,108
Commercial, industrial and agricultural loans | Unsecured | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	956	0
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	0	0
Total Past Due and Nonaccrual	0	0
Current	147,116	123,393
Total Loans	147,116	123,393
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	30	52
Total Past Due and Nonaccrual	30	136
Current	22,751	20,373
Total Loans	22,781	20,509
Installment/consumer loans | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	84
Installment/consumer loans | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	$ 0	$ 0