Loans (Details) (USD $)
12 Months Ended
Dec. 31, 2014
item
mi
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Loans        
Total $ 2,415,690,000 $ 2,295,300,000    
Less held for sale 10,400,000 13,840,000    
Total loans before allowance for loan losses 2,405,290,000 2,281,460,000    
Less allowance for loan losses 47,453,000 47,567,000 48,012,000 58,506,000
Net loans 2,357,837,000 2,233,893,000    
Net deferred loan origination costs 600,000      
Minimum target period for lending via intermediate term loans 0 years      
Maximum target period for lending via intermediate term loans 7 years      
Geographical area from lending offices which attempt is made to lend short and intermediate term loans (in miles) 125      
Direct and indirect maximum total borrowing relationship limit 20,000,000      
Borrowing relationships, threshold above which board of directors will review annually 20,000,000      
Number of primary areas for lending loan 5      
Illinois        
Loans        
Total 1,909,668,000 1,814,155,000    
Florida        
Loans        
Total 313,152,000 301,873,000    
Total loans before allowance for loan losses 312,528,000 301,125,000    
Less allowance for loan losses 8,511,000 13,118,000 15,433,000 19,469,000
Indiana        
Loans        
Total 192,870,000 179,272,000    
Commercial        
Loans        
Total 601,760,000 580,612,000    
Commercial | Illinois        
Loans        
Total 554,779,000 530,174,000    
Commercial | Florida        
Loans        
Total 16,739,000 20,536,000    
Total loans before allowance for loan losses 16,739,000 20,536,000    
Less allowance for loan losses 1,172,000 1,926,000 1,437,000 1,939,000
Commercial | Indiana        
Loans        
Total 30,242,000 29,902,000    
Commercial real estate        
Loans        
Total 1,104,151,000 1,092,273,000    
Commercial real estate | Illinois        
Loans        
Total 811,034,000 800,568,000    
Commercial real estate | Florida        
Loans        
Total 171,243,000 160,255,000    
Total loans before allowance for loan losses 171,243,000 160,255,000    
Less allowance for loan losses 4,205,000 5,733,000 6,062,000 8,413,000
Commercial real estate | Indiana        
Loans        
Total 121,874,000 131,450,000    
Real estate construction        
Loans        
Total 107,054,000 78,855,000    
Real estate construction | Illinois        
Loans        
Total 60,994,000 55,190,000    
Real estate construction | Florida        
Loans        
Total 17,950,000 17,426,000    
Total loans before allowance for loan losses 17,950,000 17,426,000    
Less allowance for loan losses 205,000 1,168,000 2,315,000 2,936,000
Real estate construction | Indiana        
Loans        
Total 28,110,000 6,239,000    
Retail real estate        
Loans        
Total 592,473,000 534,493,000    
Minimum term of long-term loans entity sells to secondary market purchasers 15 years      
Maximum term of loans entity retains 15 years      
Retail real estate | Illinois        
Loans        
Total 473,171,000 419,801,000    
Retail real estate | Florida        
Loans        
Total 106,658,000 103,104,000    
Total loans before allowance for loan losses 106,034,000 102,356,000    
Less allowance for loan losses 2,917,000 4,287,000 5,614,000 6,160,000
Retail real estate | Indiana        
Loans        
Total 12,644,000 11,588,000    
Retail other        
Loans        
Total 10,252,000 9,067,000    
Retail other | Illinois        
Loans        
Total 9,690,000 8,422,000    
Retail other | Florida        
Loans        
Total 562,000 552,000    
Total loans before allowance for loan losses 562,000 552,000    
Less allowance for loan losses 12,000 4,000 5,000 21,000
Retail other | Indiana        
Loans        
Total   $ 93,000