FAIR VALUE - Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Corporate bonds and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	$ 0	$ 0	$ 0	$ 0
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance of recurring Level 3 assets at beginning of period	0	251	0	250
Included in earnings - other non-interest income	0	0	0	0
Included in other comprehensive income	0	1	0	2
Transfers out of Level 3			0	0
Balance of recurring Level 3 assets at end of period	0	252	0	252
Derivative Liabilities
Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance of recurring Level 3 assets at beginning of period	(50)	(65)	(75)	(68)
Derivative instruments entered into	(1)	0	(1)	0
Included in earnings - other non-interest income	33	(6)	58	(3)
Included in other comprehensive income	0	0	0	0
Balance of recurring Level 3 assets at end of period	$ (18)	$ (71)	(18)	(71)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3			$ 0	$ 0