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FHLB ADVANCES AND OTHER BORROWINGS (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Oct. 12, 2021
FHLB ADVANCES AND OTHER BORROWINGS
Total FHLB advances and other borrowings	$ 360,000	$ 310,171
Preferred stock, shares issued (in shares)	115,000
Preferred stock, par value (in dollars per share)	$ 2.00
FHLB advances, collateral for mortgage and home equity line of credit loans	$ 2,710,000	2,100,000
Midland States Bancorp, Inc. \| Series G Preferred Stock
FHLB ADVANCES AND OTHER BORROWINGS
Long term debt	$ 0	$ 171
Preferred stock, shares issued (in shares)	171	171
Preferred stock, par value (in dollars per share)	$ 1,000	$ 1,000
Midland States Bancorp, Inc. \| Line of Credit
FHLB ADVANCES AND OTHER BORROWINGS
Long term debt	$ 0	$ 0
Face amount			$ 15,000
Midland States Bancorp, Inc. \| Line of Credit \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
FHLB ADVANCES AND OTHER BORROWINGS
Interest rate	1.60%	1.60%
Midland States Bank \| Putable fixed rate maturing through December 2024
FHLB ADVANCES AND OTHER BORROWINGS
Total FHLB advances and other borrowings	$ 110,000	$ 210,000
Interest rate	2.35%	1.48%
Midland States Bank \| Floater rate maturing October 2023
FHLB ADVANCES AND OTHER BORROWINGS
Total FHLB advances and other borrowings	$ 100,000	$ 100,000
Midland States Bank \| Floater rate maturing October 2023 \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
FHLB ADVANCES AND OTHER BORROWINGS
Interest rate	4.60%	1.67%
Midland States Bank \| Short term fixed rate maturing through October 2022
FHLB ADVANCES AND OTHER BORROWINGS
Total FHLB advances and other borrowings	$ 150,000	$ 0
Interest rate	3.14%	3.14%