FAIR VALUE - Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Corporate Bonds and Notes
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance of recurring Level 3 assets at beginning of period	$ 0	$ 252	$ 0	$ 250
Derivative instruments entered into	0	0	0	0
Included in earnings - other non-interest income	0	0	0	0
Included in other comprehensive income	0	(10)	0	(8)
Transfers out of Level 3	0	(242)	0	242
Balance of recurring Level 3 assets at end of period	0	0	0	0
Derivative Liabilities
Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance of recurring Level 3 assets at beginning of period	(18)	(71)	(75)	(68)
Derivative instruments entered into	0	0	0	(1)
Included in earnings - other non-interest income	5	0	62	(2)
Included in other comprehensive income	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance of recurring Level 3 assets at end of period	$ (13)	$ (71)	$ (13)	$ (71)