Borrowings - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Borrowings
Total borrowings	$ 212,984	$ 197,304
Securities sold under repurchase agreements
Borrowings
Total borrowings	36,361	25,715
FHLBC advances
Borrowings
Total borrowings	75,000	70,000
Junior subordinated debentures
Borrowings
Total borrowings	$ 57,615	$ 57,591