BUSINESS SEGMENTS - Schedule of Income and Total Assets for Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Net interest income	$ 29,268	$ 29,243	$ 59,275	$ 57,636
Noninterest income	13,026	11,740	24,755	21,955
Total income	42,294	40,983	84,030	79,591
Provision for loan and lease losses	1,150	300	1,250	1,550
Compensation and benefits	17,543	15,826	34,699	30,405
Premises and equipment expense	3,600	3,406	6,988	6,676
FDIC expense	277	625	554	1,205
Other noninterest expense	4,753	5,084	9,647	9,992
Total noninterest expense	27,323	25,241	53,138	49,828
Income before income tax expense	14,971	15,742	30,892	29,763
Income tax expense	3,421	3,832	7,917	7,046
NET INCOME	11,550	11,910	22,975	22,717
Total assets at period end	4,871,234	4,265,174	4,871,234	4,265,174	$ 4,617,858
Banking [Member]
Net interest income	27,934	27,953	56,500	54,801
Noninterest income	3,151	3,353	5,430	4,980
Total income	31,085	31,306	61,930	59,781
Provision for loan and lease losses	1,150	300	1,250	1,550
Compensation and benefits	12,685	11,932	24,682	22,263
Premises and equipment expense	3,046	2,982	5,971	5,821
FDIC expense	277	625	554	1,205
Other noninterest expense	2,553	3,145	5,311	5,952
Total noninterest expense	19,711	18,984	37,768	36,791
Income before income tax expense	11,374	12,322	24,162	22,990
Income tax expense	2,581	2,997	6,192	5,442
NET INCOME	8,793	9,325	17,970	17,548
Total assets at period end	4,791,902	4,208,731	4,791,902	4,208,731
Wealth Management Division [Member]
Net interest income	1,334	1,290	2,775	2,835
Noninterest income	9,875	8,387	19,325	16,975
Total income	11,209	9,677	22,100	19,810
Provision for loan and lease losses	0	0	0	0
Compensation and benefits	4,858	3,894	10,017	8,142
Premises and equipment expense	554	424	1,017	855
FDIC expense	0	0	0	0
Other noninterest expense	2,200	1,939	4,336	4,040
Total noninterest expense	7,612	6,257	15,370	13,037
Income before income tax expense	3,597	3,420	6,730	6,773
Income tax expense	840	835	1,725	1,604
NET INCOME	2,757	2,585	5,005	5,169
Total assets at period end	$ 79,332	$ 56,443	$ 79,332	$ 56,443