PREMISES AND EQUIPMENT, NET (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2017 item	Nov. 30, 2016 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Premises and equipment gross			$ 92,499	$ 95,667
Accumulated depreciation			(25,807)	(22,534)
Premises and equipment, net			66,692	73,133
Other Assets.			40,259	29,260
Depreciation			5,080	5,139	$ 3,464
Number Of Banking Offices | item		46
Asset impairment		$ 1,900
Increase in assets held for sale		1,600
Decrease in premises and equipment		$ 1,600
Forecast
Property, Plant and Equipment [Line Items]
Number Of Banking Offices | item	39
Land
Property, Plant and Equipment [Line Items]
Premises and equipment gross			14,314	14,942
Buildings and improvements
Property, Plant and Equipment [Line Items]
Premises and equipment gross			56,766	58,922
Equipment
Property, Plant and Equipment [Line Items]
Premises and equipment gross			21,419	21,803
Midland States Bancorp, Inc
Property, Plant and Equipment [Line Items]
Other Assets.			$ 2,047	$ 3,644