SECURITIES - Other than temporary impairment (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($) Security	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Other than temporary impairment [Abstract]
Amortized cost of securities sold			$ 344,195
Proceeds from sale of securities			72,718	$ 36,258	$ 2,650
Other than temporary impairment credit losses recognized in earnings [Roll Forward]
Beginning balance	$ 1,939		0	1,939	3,506
Additions/Subtractions:
Reductions for previous credit losses realized on securities sold during the year			0	0	(1,596)
Reductions for previous credit losses realized on securities liquidated during the year			0	(1,939)	0
Increases to the amount related to the credit loss for which other-than-temporary impairment was previously recognized			0	0	29
Ending balance		$ 1,939	$ 0	$ 0	1,939
Collateralized Debt Obligations
Other than temporary impairment [Abstract]
Number of securities sold | Security		1
Amortized cost of securities sold		$ 600			600
Proceeds from sale of securities					600
Additional credit loss in OTTI recognized					$ 29
Additions/Subtractions:
Income from liquidation of debt securities	$ 515