REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Other noninterest income - ASC 606									$ 4,432	$ 4,569	$ 4,273
Total noninterest income in scope of ASC 606									68,709	64,259	61,875
Total noninterest income out of scope of ASC 606									19,796	18,735	20,553
Noninterest Income	$ 23,491	$ 23,264	$ 21,887	$ 19,863	$ 21,914	$ 20,770	$ 21,398	$ 18,912	88,505	82,994	82,428
Deposit Account [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									18,327	17,822	18,652
Credit Card, Merchant Discount [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									15,433	13,899	12,842
ATM Charge [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									2,961	2,938	3,093
Investment Advisory, Management and Administrative Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									23,441	21,644	19,587
Investment Advisory, Retail Investment and Insurance Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									2,714	2,158	2,222
Merchant Processing [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									$ 1,401	$ 1,229	$ 1,206