SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2016
Building | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	37 years
Building | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years
Furniture, Software, and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Furniture, Software, and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years