LOANS - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Past Due and Nonaccrual Loans
>90 Days Past Due and Accruing	$ 338	$ 308
Nonaccrual Including 90 Days or More Past Due	4,211	2,808
Total Past Due and Nonaccrual	10,535	7,516
Current	3,490,433	3,261,256
Total Loans	3,500,968	3,268,772
30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	4,544	3,780
60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	1,442	620
Commercial Real Estate | Mortgage loans
Past Due and Nonaccrual Loans
Total Loans	1,519,807	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	231	253
Total Past Due and Nonaccrual	1,156	780
Current	528,327	509,618
Total Loans	529,483	510,398
Commercial Real Estate | Mortgage loans | Owner occupied | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	729	333
Commercial Real Estate | Mortgage loans | Owner occupied | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	196	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	512	885
Total Past Due and Nonaccrual	512	885
Current	989,812	862,273
Total Loans	990,324	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	0	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	673,909	585,827
Total Loans	673,909	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	497,842	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	2,100	199
Total Past Due and Nonaccrual	5,346	1,321
Current	423,608	447,194
Total Loans	428,954	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	3,246	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	338	308
Nonaccrual Including 90 Days or More Past Due	368	624
Total Past Due and Nonaccrual	1,067	1,965
Current	67,821	69,283
Total Loans	68,888	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	61	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	300	0
Commercial, industrial and agricultural loans
Past Due and Nonaccrual Loans
Total Loans	667,949	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	211	174
Total Past Due and Nonaccrual	543	700
Current	160,265	167,840
Total Loans	160,808	168,540
Commercial, industrial and agricultural loans | Secured | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	0	330
Commercial, industrial and agricultural loans | Secured | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	332	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	652	621
Total Past Due and Nonaccrual	1,751	1,729
Current	505,390	475,455
Total Loans	507,141	477,184
Commercial, industrial and agricultural loans | Unsecured | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	485	1,108
Commercial, industrial and agricultural loans | Unsecured | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	614	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	125	0
Total Past Due and Nonaccrual	125	0
Current	116,338	123,393
Total Loans	116,463	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	12	52
Total Past Due and Nonaccrual	35	136
Current	24,963	20,373
Total Loans	24,998	20,509
Installment/consumer loans | 30-59 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	23	84
Installment/consumer loans | 60-89 Days Past Due
Past Due and Nonaccrual Loans
Total Past Due and Nonaccrual	$ 0	$ 0