SUPPLEMENTAL DATA (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 36,439	$ 37,491	$ 33,412	$ 31,385	$ 30,271	$ 29,844	$ 29,035	$ 27,898	$ 27,123	$ 25,806	$ 23,852	$ 22,361	$ 138,727	$ 117,048	$ 99,142
Interest expense	7,853	7,499	6,440	5,794	5,691	5,575	4,859	4,488	4,304	4,100	3,508	2,778	27,586	20,613	14,690
Net interest income	28,586	29,992	26,972	25,591	24,580	24,269	24,176	23,410	22,819	21,706	20,344	19,583	111,141	96,435	84,452
Provision for loan losses	1,650	400	2,200	1,600	1,500	2,100	2,200	1,700	1,950	1,600	2,200	1,350	5,850	7,500	7,100
Wealth management fee income	7,489	5,790	5,086	4,818	4,610	4,436	4,899	4,295	4,307	4,169	4,532	4,031	23,183	18,240	17,039
Securities gains/(losses), net							18	101		83	176	268		119	527
Other income	3,117	3,041	3,085	2,201	3,062	3,099	2,531	1,867	1,416	1,358	1,791	1,583	2,814	1,638	373
Operating expenses	24,251	21,961	20,095	19,304	18,965	18,166	18,775	19,206	19,993	16,899	16,266	15,768
Income before income tax expense	13,291	16,462	12,848	11,706	11,787	11,538	10,649	8,767	6,599	8,817	8,377	8,347	54,307	42,741	32,140
Income tax expense	2,922	6,256	4,908	3,724	4,479	4,422	4,085	3,278	2,256	3,434	3,139	3,339	17,810	16,264	12,168
Net income	$ 10,369	$ 10,206	$ 7,940	$ 7,982	$ 7,308	$ 7,116	$ 6,564	$ 5,489	$ 4,343	$ 5,383	$ 5,238	$ 5,008	$ 36,497	$ 26,477	$ 19,972
EARNINGS PER COMMON SHARE
Earnings per share-basic	$ 0.57	$ 0.57	$ 0.45	$ 0.47	$ 0.44	$ 0.43	$ 0.41	$ 0.35	$ 0.28	$ 0.35	$ 0.34	$ 0.34	$ 2.06	$ 1.62	$ 1.31
Earnings per share-diluted	$ 0.56	$ 0.56	$ 0.45	$ 0.46	$ 0.43	$ 0.43	$ 0.4	$ 0.34	$ 0.28	$ 0.35	$ 0.34	$ 0.33	$ 2.03	$ 1.60	$ 1.29