REVENUE FROM CONTRACT WITH CUSTOMERS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Noninterest income - out-of-scope of Topic 606	$ (3,857)
Total noninterest income	8,598	$ 17,075
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - out-of-scope of Topic 606		5,729
Total noninterest income		17,075
Trust management/administration fees
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	4,209
Trust management/administration fees | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		3,617
Investment advisory fees
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	529
Investment advisory fees | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		529
Investment brokerage fees
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	395
Investment brokerage fees | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		219
Other
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	544
Other | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		588
Nonsufficient fund fees
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	1,866
Nonsufficient fund fees | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		1,754
Other
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	790
Other | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		766
Interchange revenues
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	2,833
Interchange revenues | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		2,680
Merchant services revenue
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	351
Merchant services revenue | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		375
Other.
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606	$ 938
Other. | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Noninterest income - in-scope of Topic 606		$ 818