TRUST PREFERRED DEBNTURES (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 09, 2017	Dec. 31, 2016	Jun. 05, 2013	Jun. 07, 2007	Nov. 30, 2006	Apr. 30, 2004	Mar. 26, 2004
TRUST PREFERRED DEBENTURES
Trust preferred debentures	$ 45,156,000		$ 37,405,000
Centrue
TRUST PREFERRED DEBENTURES
Book value of subordinated debentures		$ 10,000,000
Liquidation amount per security							$ 1,000
Number of preferred securities issued							10,000
Fair value of subordinated debentures		$ 7,600,000
Centrue Bank
TRUST PREFERRED DEBENTURES
Trust preferred debentures	7,569,000
Trust preferred debentures maturing January 23, 2034
TRUST PREFERRED DEBENTURES
Trust preferred debentures	$ 2,028,000		$ 1,996,000
Trust preferred debentures maturing January 23, 2034 | Grant Park Trust
TRUST PREFERRED DEBENTURES
Face amount				$ 3,000,000
Trust preferred debentures maturing January 23, 2034 | Grant Park Trust | LIBOR
TRUST PREFERRED DEBENTURES
Variable interest rate (as a percent)	2.85%
Interest rate (as a percent)	4.02%		3.74%
Trust preferred debentures maturing April 23, 2034
TRUST PREFERRED DEBENTURES
Trust preferred debentures	$ 9,958,000		$ 9,957,000
Trust preferred debentures maturing April 23, 2034 | Midland Trust
TRUST PREFERRED DEBENTURES
Face amount								$ 10,000,000
Trust preferred debentures maturing April 23, 2034 | Midland Trust | LIBOR
TRUST PREFERRED DEBENTURES
Variable interest rate (as a percent)	2.75%
Interest rate (as a percent)	3.90%		3.63%
Trust preferred debentures maturing December 31, 2036
TRUST PREFERRED DEBENTURES
Trust preferred debentures	$ 13,215,000		$ 13,141,000
Trust preferred debentures maturing December 31, 2036 | LSHC Trust III
TRUST PREFERRED DEBENTURES
Face amount						$ 20,000,000
Trust preferred debentures maturing December 31, 2036 | LSHC Trust III | LIBOR
TRUST PREFERRED DEBENTURES
Variable interest rate (as a percent)	1.75%
Interest rate (as a percent)	3.00%		2.71%
Trust preferred debentures maturing September 6, 2037
TRUST PREFERRED DEBENTURES
Trust preferred debentures	$ 12,386,000		$ 12,311,000
Trust preferred debentures maturing September 6, 2037 | LSHC Trust IV
TRUST PREFERRED DEBENTURES
Face amount					$ 20,000,000
Trust preferred debentures maturing September 6, 2037 | LSHC Trust IV | LIBOR
TRUST PREFERRED DEBENTURES
Variable interest rate (as a percent)	1.47%
Interest rate (as a percent)	2.69%		2.42%
Trust preferred debentures maturing April 22, 2034 | Centrue Bank
TRUST PREFERRED DEBENTURES
Face amount							$ 10,000
Trust preferred debentures maturing April 22, 2034 | Centrue Bank | LIBOR
TRUST PREFERRED DEBENTURES
Variable interest rate (as a percent)	2.65%
Interest rate (as a percent)	3.92%
Other assets | Centrue Bank
TRUST PREFERRED DEBENTURES
Company's investment in the common stock of trust							$ 310,000