CAPITAL REQUIREMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Capital requirements and restrictions on dividends
Total Capital (to Risk Weighted Assets): Actual Amount	$ 457,097	$ 374,955
Total Capital (to Risk Weighted Assets): Actual Ratio	12.34%	13.85%
Total Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Amount	$ 296,298	$ 216,612
Total Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Ratio	8.00%	8.00%
Tier I Capital (to Risk Weighted Assets): Actual Amount	$ 386,864	$ 305,283
Tier I Capital (to Risk Weighted Assets): Actual Ratio	10.45%	11.27%
Tier I Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Amount	$ 222,223	$ 162,459
Tier I Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Ratio	6.00%	6.00%
Common equity Tier 1 capital (to risk-weighted assets): Actual Amount	$ 321,445	$ 253,273
Common equity Tier 1 capital (to risk-weighted assets): Actual Ratio	8.68%	9.35%
Common equity Tier 1 capital (to risk-weighted assets): Minimum Required for adequate capital Amount	$ 166,667	$ 121,844
Common equity Tier 1 capital (to risk-weighted assets): Minimum Required for adequate capital Ratio	4.50%	4.50%
Tier I Capital (to Average Assets): Actual Amount	$ 386,864	$ 305,283
Tier I Capital (to Average Assets): Actual Ratio	11.04%	9.76%
Tier I Capital (to Average Assets): Minimum Required For Adequate Capital Purposes Amount	$ 140,216	$ 125,076
Tier I Capital (to Average Assets): Minimum Required For Adequate Capital Purposes Ratio	4.00%	4.00%
Midland States Bank
Capital requirements and restrictions on dividends
Total Capital (to Risk Weighted Assets): Actual Amount	$ 333,095	$ 329,759
Total Capital (to Risk Weighted Assets): Actual Ratio	11.61%	12.17%
Total Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Amount	$ 229,425	$ 216,773
Total Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Ratio	8.00%	8.00%
Total Capital (to Risk Weighted Assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 286,782	$ 270,966
Total Capital (to Risk Weighted Assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	10.00%	10.00%
Tier I Capital (to Risk Weighted Assets): Actual Amount	$ 317,433	$ 314,595
Tier I Capital (to Risk Weighted Assets): Actual Ratio	11.07%	11.61%
Tier I Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Amount	$ 172,069	$ 162,580
Tier I Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Ratio	6.00%	6.00%
Tier I Capital (to Risk Weighted Assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 229,425	$ 216,773
Tier I Capital (to Risk Weighted Assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	8.00%	8.00%
Common equity Tier 1 capital (to risk-weighted assets): Actual Amount	$ 317,433	$ 314,595
Common equity Tier 1 capital (to risk-weighted assets): Actual Ratio	11.07%	11.61%
Common equity Tier 1 capital (to risk-weighted assets): Minimum Required for adequate capital Amount	$ 129,052	$ 121,935
Common equity Tier 1 capital (to risk-weighted assets): Minimum Required for adequate capital Ratio	4.50%	4.50%
Common equity Tier 1 capital (to risk-weighted assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 186,408	$ 176,128
Common equity Tier 1 capital (to risk-weighted assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	6.50%	6.50%
Tier I Capital (to Average Assets): Actual Amount	$ 317,433	$ 314,595
Tier I Capital (to Average Assets): Actual Ratio	9.56%	10.05%
Tier I Capital (to Average Assets): Minimum Required For Adequate Capital Purposes Amount	$ 132,857	$ 125,271
Tier I Capital (to Average Assets): Minimum Required For Adequate Capital Purposes Ratio	4.00%	4.00%
Tier I Capital (to Average Assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 166,071	$ 156,589
Tier I Capital (to Average Assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	5.00%	5.00%
Centrue Bank
Capital requirements and restrictions on dividends
Total Capital (to Risk Weighted Assets): Actual Amount	$ 102,693
Total Capital (to Risk Weighted Assets): Actual Ratio	12.89%
Total Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Amount	$ 63,735
Total Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Ratio	8.00%
Total Capital (to Risk Weighted Assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 79,669
Total Capital (to Risk Weighted Assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	10.00%
Tier I Capital (to Risk Weighted Assets): Actual Amount	$ 102,677
Tier I Capital (to Risk Weighted Assets): Actual Ratio	12.89%
Tier I Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Amount	$ 47,801
Tier I Capital (to Risk Weighted Assets): Minimum Required For Adequate Capital Purposes Ratio	6.00%
Tier I Capital (to Risk Weighted Assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 63,735
Tier I Capital (to Risk Weighted Assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	8.00%
Common equity Tier 1 capital (to risk-weighted assets): Actual Amount	$ 102,677
Common equity Tier 1 capital (to risk-weighted assets): Actual Ratio	12.89%
Common equity Tier 1 capital (to risk-weighted assets): Minimum Required for adequate capital Amount	$ 35,851
Common equity Tier 1 capital (to risk-weighted assets): Minimum Required for adequate capital Ratio	4.50%
Common equity Tier 1 capital (to risk-weighted assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 51,785
Common equity Tier 1 capital (to risk-weighted assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	6.50%
Tier I Capital (to Average Assets): Actual Amount	$ 102,677
Tier I Capital (to Average Assets): Actual Ratio	10.80%
Tier I Capital (to Average Assets): Minimum Required For Adequate Capital Purposes Amount	$ 38,034
Tier I Capital (to Average Assets): Minimum Required For Adequate Capital Purposes Ratio	4.00%
Tier I Capital (to Average Assets): Required to be Well Capitalized Amount Under Prompt Corrective Action Requirements	$ 47,543
Tier I Capital (to Average Assets): Required to be Well Capitalized Ratio Under Prompt Corrective Action Requirements	5.00%