INCOME TAXES, Components of Net Deferred Tax Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Components of net deferred tax liability [Abstract]
Allowance for loan losses	$ 18,366	$ 17,791
Employee benefits	6,311	6,633
Debt extinguishment	299	613
Other, net	5,202	9,704
Deferred tax asset	30,178	34,741
Investment securities	32,839	38,314
Tax-deductible goodwill	43,504	39,724
Loan origination costs	8,228	7,295
Depreciation	71	886
Mortgage servicing rights	548	565
Pension	18,194	14,807
Deferred tax liability	103,384	101,591
Net deferred tax liability	$ (73,206)	$ (66,850)