XML 73 R57.htm IDEA: XBRL DOCUMENT v3.8.0.1
Business and Summary of Significant Accounting Policies - Nature of business (Details)
 12 Months Ended
Jun. 14, 2017
USD ($)
$ / shares
Dec. 31, 2017
item
Nature of business    
Merger transaction, the number of shares into which each share of common stock issued and outstanding prior to merger was converted 0.20  
Merger transaction, cash paid to stockholders for remaining fractional shares | $ $ 2,000  
Offering price per share | $ / shares $ 19.00  
Chicago metropolitan area    
Nature of business    
Number of bank branches   55
Wisconsin    
Nature of business    
Number of bank branches   1