FAIR VALUES - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Corporate bonds and notes
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance of recurring Level 3 assets at January 1	$ 0	$ 250
Derivative instruments entered into	0	0
Total gains or losses for the period:
Included in earnings - other non-interest income	0	0
Included in other comprehensive income	0	1
Transfers out of Level 3	0	(251)
Balance of recurring Level 3 assets at December 31	0	0
Derivative liabilities
Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance of recurring Level 3 assets at January 1	(75)	(68)
Derivative instruments entered into	(1)	(5)
Included in earnings - other non-interest income	(64)	(2)
Included in other comprehensive income	0	0
Transfers out of Level 3	0	0
Balance of recurring Level 3 assets at December 31	$ (140)	$ (75)