LOANS - Categorized by Class and Internally Assigned Risk Grades (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans by class categorized by internally assigned risk grades
Total loans	$ 3,191,408	$ 3,098,253
Pass
Loans by class categorized by internally assigned risk grades
Total loans	3,119,915	3,012,960
Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	25,283	42,610
Substandard
Loans by class categorized by internally assigned risk grades
Total loans	46,210	42,683
Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Commercial Real Estate | Mortgage loans
Loans by class categorized by internally assigned risk grades
Total loans	1,348,569	1,293,906
Commercial Real Estate | Mortgage loans | Owner occupied
Loans by class categorized by internally assigned risk grades
Total loans	498,327	472,649
Commercial Real Estate | Mortgage loans | Owner occupied | Pass
Loans by class categorized by internally assigned risk grades
Total loans	479,536	451,264
Commercial Real Estate | Mortgage loans | Owner occupied | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	812	1,796
Commercial Real Estate | Mortgage loans | Owner occupied | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	17,979	19,589
Commercial Real Estate | Mortgage loans | Owner occupied | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Commercial Real Estate | Mortgage loans | Non-owner occupied
Loans by class categorized by internally assigned risk grades
Total loans	850,242	821,257
Commercial Real Estate | Mortgage loans | Non-owner occupied | Pass
Loans by class categorized by internally assigned risk grades
Total loans	846,780	808,612
Commercial Real Estate | Mortgage loans | Non-owner occupied | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	520	8,056
Commercial Real Estate | Mortgage loans | Non-owner occupied | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	2,942	4,589
Commercial Real Estate | Mortgage loans | Non-owner occupied | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Multi-family | Mortgage loans
Loans by class categorized by internally assigned risk grades
Total loans	579,827	595,280
Multi-family | Mortgage loans | Pass
Loans by class categorized by internally assigned risk grades
Total loans	579,403	595,280
Multi-family | Mortgage loans | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	424	0
Multi-family | Mortgage loans | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Multi-family | Mortgage loans | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Residential real estate | Mortgage loans
Loans by class categorized by internally assigned risk grades
Total loans	516,995	464,264
Residential real estate | Mortgage loans | Residential Real Estate Mortgage Loans
Loans by class categorized by internally assigned risk grades
Total loans	447,769	398,173
Residential real estate | Mortgage loans | Residential Real Estate Mortgage Loans | Pass
Loans by class categorized by internally assigned risk grades
Total loans	438,158	393,029
Residential real estate | Mortgage loans | Residential Real Estate Mortgage Loans | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	8,729	4,854
Residential real estate | Mortgage loans | Residential Real Estate Mortgage Loans | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	882	290
Residential real estate | Mortgage loans | Residential Real Estate Mortgage Loans | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Residential real estate | Mortgage loans | Home equity
Loans by class categorized by internally assigned risk grades
Total loans	69,226	66,091
Residential real estate | Mortgage loans | Home equity | Pass
Loans by class categorized by internally assigned risk grades
Total loans	67,047	64,601
Residential real estate | Mortgage loans | Home equity | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	1,006	698
Residential real estate | Mortgage loans | Home equity | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	1,173	792
Residential real estate | Mortgage loans | Home equity | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Commercial and industrial
Loans by class categorized by internally assigned risk grades
Total loans	608,723	616,003
Commercial and industrial | Secured
Loans by class categorized by internally assigned risk grades
Total loans	118,380	112,313
Commercial and industrial | Secured | Pass
Loans by class categorized by internally assigned risk grades
Total loans	95,164	86,116
Commercial and industrial | Secured | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	6,306	12,637
Commercial and industrial | Secured | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	16,910	13,560
Commercial and industrial | Secured | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Commercial and industrial | Unsecured
Loans by class categorized by internally assigned risk grades
Total loans	490,343	503,690
Commercial and industrial | Unsecured | Pass
Loans by class categorized by internally assigned risk grades
Total loans	477,039	485,598
Commercial and industrial | Unsecured | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	7,476	14,553
Commercial and industrial | Unsecured | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	5,828	3,539
Commercial and industrial | Unsecured | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Real estate construction and land loans
Loans by class categorized by internally assigned risk grades
Total loans	118,137	107,759
Real estate construction and land loans | Pass
Loans by class categorized by internally assigned risk grades
Total loans	117,677	107,440
Real estate construction and land loans | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Real estate construction and land loans | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	460	319
Real estate construction and land loans | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	0	0
Installment/consumer loans
Loans by class categorized by internally assigned risk grades
Total loans	19,157	21,041
Installment/consumer loans | Pass
Loans by class categorized by internally assigned risk grades
Total loans	19,111	21,020
Installment/consumer loans | Special Mention
Loans by class categorized by internally assigned risk grades
Total loans	10	16
Installment/consumer loans | Substandard
Loans by class categorized by internally assigned risk grades
Total loans	36	5
Installment/consumer loans | Doubtful
Loans by class categorized by internally assigned risk grades
Total loans	$ 0	$ 0