Loans (Details 6) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Changes in allowance for loan losses      
Beginning balance $ 47,567 $ 48,012 $ 58,506
Provision for loan loss 2,000 7,500 16,500
Charged-off (7,371) (10,669) (30,063)
Recoveries 5,257 2,724 3,069
Ending Balance 47,453 47,567 48,012
Amount allocated to:      
Ending Balance 47,453 47,567 48,012
Loans:      
Ending Balance 2,405,290 2,281,460  
Illinois/Indiana      
Changes in allowance for loan losses      
Beginning balance 34,449 32,579 39,037
Provision for loan loss 6,532 6,350 15,891
Charged-off (5,519) (6,235) (23,975)
Recoveries 3,480 1,755 1,626
Ending Balance 38,942 34,449 32,579
Amount allocated to:      
Loans individually evaluated for impairment 2,641 3,534  
Loans collectively evaluated for impairment 36,301 30,915  
Ending Balance 38,942 34,449 32,579
Loans:      
Loans individually evaluated for impairment 8,593 18,836  
Loans collectively evaluated for impairment 2,084,169 1,961,499  
Ending Balance 2,092,762 1,980,335  
Florida      
Changes in allowance for loan losses      
Beginning balance 13,118 15,433 19,469
Provision for loan loss (4,532) 1,150 609
Charged-off (1,852) (4,434) (6,088)
Recoveries 1,777 969 1,443
Ending Balance 8,511 13,118 15,433
Amount allocated to:      
Loans individually evaluated for impairment 527 753  
Loans collectively evaluated for impairment 7,984 12,365  
Ending Balance 8,511 13,118 15,433
Loans:      
Loans individually evaluated for impairment 17,993 15,224  
Loans collectively evaluated for impairment 294,535 285,901  
Ending Balance 312,528 301,125  
Commercial | Illinois/Indiana      
Changes in allowance for loan losses      
Beginning balance 8,452 6,597 9,143
Provision for loan loss 1,048 2,681 1,428
Charged-off (864) (964) (4,176)
Recoveries 233 138 202
Ending Balance 8,869 8,452 6,597
Amount allocated to:      
Loans individually evaluated for impairment 595 485  
Loans collectively evaluated for impairment 8,274 7,967  
Ending Balance 8,869 8,452 6,597
Loans:      
Loans individually evaluated for impairment 2,117 2,286  
Loans collectively evaluated for impairment 582,904 557,790  
Ending Balance 585,021 560,076  
Commercial | Florida      
Changes in allowance for loan losses      
Beginning balance 1,926 1,437 1,939
Provision for loan loss 195 414 (811)
Charged-off (1,126)   (246)
Recoveries 177 75 555
Ending Balance 1,172 1,926 1,437
Amount allocated to:      
Loans collectively evaluated for impairment 1,172 1,926  
Ending Balance 1,172 1,926 1,437
Loans:      
Loans individually evaluated for impairment 1,642    
Loans collectively evaluated for impairment 15,097 20,536  
Ending Balance 16,739 20,536  
Commercial real estate | Illinois/Indiana      
Changes in allowance for loan losses      
Beginning balance 16,379 15,023 18,605
Provision for loan loss (880) 2,143 10,058
Charged-off (1,173) (1,361) (14,016)
Recoveries 2,108 574 376
Ending Balance 16,434 16,379 15,023
Amount allocated to:      
Loans individually evaluated for impairment 1,975 1,977  
Loans collectively evaluated for impairment 14,459 14,402  
Ending Balance 16,434 16,379 15,023
Loans:      
Loans individually evaluated for impairment 3,994 7,411  
Loans collectively evaluated for impairment 928,914 924,607  
Ending Balance 932,908 932,018  
Commercial real estate | Florida      
Changes in allowance for loan losses      
Beginning balance 5,733 6,062 8,413
Provision for loan loss (1,799) 2,225 (619)
Charged-off   (2,543) (1,858)
Recoveries 271 (11) 126
Ending Balance 4,205 5,733 6,062
Amount allocated to:      
Loans individually evaluated for impairment 370 416  
Loans collectively evaluated for impairment 3,835 5,317  
Ending Balance 4,205 5,733 6,062
Loans:      
Loans individually evaluated for impairment 5,688 5,265  
Loans collectively evaluated for impairment 165,555 154,990  
Ending Balance 171,243 160,255  
Real estate construction | Illinois/Indiana      
Changes in allowance for loan losses      
Beginning balance 2,540 2,527 4,352
Provision for loan loss 90 847 (270)
Charged-off (657) (1,212) (1,883)
Recoveries 617 378 328
Ending Balance 2,590 2,540 2,527
Amount allocated to:      
Loans individually evaluated for impairment 46 468  
Loans collectively evaluated for impairment 2,544 2,072  
Ending Balance 2,590 2,540 2,527
Loans:      
Loans individually evaluated for impairment 46 3,862  
Loans collectively evaluated for impairment 89,058 57,567  
Ending Balance 89,104 61,429  
Real estate construction | Florida      
Changes in allowance for loan losses      
Beginning balance 1,168 2,315 2,936
Provision for loan loss (1,889) (1,419) (555)
Charged-off (69) (56) (336)
Recoveries 995 328 270
Ending Balance 205 1,168 2,315
Amount allocated to:      
Loans collectively evaluated for impairment 205 1,168  
Ending Balance 205 1,168 2,315
Loans:      
Loans individually evaluated for impairment 551 417  
Loans collectively evaluated for impairment 17,399 17,009  
Ending Balance 17,950 17,426  
Retail real estate | Illinois/Indiana      
Changes in allowance for loan losses      
Beginning balance 6,862 8,110 6,473
Provision for loan loss 5,942 616 4,397
Charged-off (2,396) (2,187) (3,264)
Recoveries 337 323 504
Ending Balance 10,745 6,862 8,110
Amount allocated to:      
Loans individually evaluated for impairment 25 604  
Loans collectively evaluated for impairment 10,720 6,258  
Ending Balance 10,745 6,862 8,110
Loans:      
Loans individually evaluated for impairment 2,428 5,277  
Loans collectively evaluated for impairment 473,611 413,020  
Ending Balance 476,039 418,297  
Retail real estate | Florida      
Changes in allowance for loan losses      
Beginning balance 4,287 5,614 6,160
Provision for loan loss (1,021) (51) 2,626
Charged-off (656) (1,828) (3,646)
Recoveries 307 552 474
Ending Balance 2,917 4,287 5,614
Amount allocated to:      
Loans individually evaluated for impairment 150 337  
Loans collectively evaluated for impairment 2,767 3,950  
Ending Balance 2,917 4,287 5,614
Loans:      
Loans individually evaluated for impairment 10,105 9,542  
Loans collectively evaluated for impairment 95,929 92,814  
Ending Balance 106,034 102,356  
Retail other | Illinois/Indiana      
Changes in allowance for loan losses      
Beginning balance 216 322 464
Provision for loan loss 332 63 278
Charged-off (429) (511) (636)
Recoveries 185 342 216
Ending Balance 304 216 322
Amount allocated to:      
Loans collectively evaluated for impairment 304 216  
Ending Balance 304 216 322
Loans:      
Loans individually evaluated for impairment 8    
Loans collectively evaluated for impairment 9,682 8,515  
Ending Balance 9,690 8,515  
Retail other | Florida      
Changes in allowance for loan losses      
Beginning balance 4 5 21
Provision for loan loss (18) (19) (32)
Charged-off (1) (7) (2)
Recoveries 27 25 18
Ending Balance 12 4 5
Amount allocated to:      
Loans individually evaluated for impairment 7    
Loans collectively evaluated for impairment 5 4  
Ending Balance 12 4 5
Loans:      
Loans individually evaluated for impairment 7    
Loans collectively evaluated for impairment 555 552  
Ending Balance $ 562 $ 552