Capital (Details 2) (USD $)
1 Months Ended 0 Months Ended 72 Months Ended
Jul. 31, 2013
Oct. 22, 2014
Jan. 22, 2013
Dec. 31, 2014
Dec. 31, 2013
Total Capital (to Risk Weighted Assets), Amount          
Actual       $ 488,908,000 $ 449,407,000
Minimum Capital Requirement       209,554,000 197,422,000
Minimum To Be Well Capitalized       261,942,000 246,777,000
Total Capital (to Risk Weighted Assets), Ratio          
Actual (as a percent)       18.66% 18.21%
Minimum Capital Requirement (as a percent)       8.00% 8.00%
Minimum To Be Well Capitalized (as a percent)       10.00% 10.00%
Tier 1 Capital (to Risk Weighted Assets), Amount          
Actual       455,354,000 417,564,000
Minimum Capital Requirement       104,777,000 98,711,000
Minimum To Be Well Capitalized       157,166,000 148,067,000
Tier 1 Capital (to Risk Weighted Assets), Ratio          
Actual (as a percent)       17.38% 16.92%
Minimum Capital Requirement (as a percent)       4.00% 4.00%
Minimum To Be Well Capitalized (as a percent)       6.00% 6.00%
Tier 1 Capital (to Average Assets), Amount          
Actual       455,354,000 417,564,000
Minimum Capital Requirement       142,401,000 138,896,000
Tier 1 Capital (to Average Assets), Ratio          
Actual (as a percent)       12.79% 12.02%
Minimum Capital Requirement (as a percent)       4.00% 4.00%
Maximum assets of bank holding companies for inclusion of proceeds of trust preferred securities from Tier 1 capital unless such securities were issued prior to May 19, 2010       15,000,000,000  
Dodd-Frank Act ("Basel III Rules")          
Total Capital (to Risk Weighted Assets), Ratio          
Minimum To Be Well Capitalized (as a percent) 10.00%        
Tier 1 Capital (to Risk Weighted Assets), Ratio          
Minimum To Be Well Capitalized (as a percent) 8.00%        
Tier 1 Capital (to Average Assets), Ratio          
Common equity Tier 1 Risk Based Capital to be well capitalized percentage 6.50%        
Tier 1 Leverage Capital to be well capitalized percentage 5.00%        
Maximum consolidated assets of bank holding companies 1,000,000,000        
Maximum consolidated assets of bank holding companies to retain the existing treatment for accumulated other comprehensive income which currently does not affect regulatory capital       15,000,000,000  
Busey Bank          
Regulatory Capital          
Dividends paid       0  
Distribution received through chartered amendment   60,000,000 50,000,000    
Total Capital (to Risk Weighted Assets), Amount          
Actual       388,479,000 396,248,000
Minimum Capital Requirement       207,991,000 196,002,000
Minimum To Be Well Capitalized       259,988,000 245,002,000
Total Capital (to Risk Weighted Assets), Ratio          
Actual (as a percent)       14.94% 16.17%
Minimum Capital Requirement (as a percent)       8.00% 8.00%
Minimum To Be Well Capitalized (as a percent)       10.00% 10.00%
Tier 1 Capital (to Risk Weighted Assets), Amount          
Actual       355,166,000 364,625,000
Minimum Capital Requirement       103,996,000 98,001,000
Minimum To Be Well Capitalized       155,993,000 147,001,000
Tier 1 Capital (to Risk Weighted Assets), Ratio          
Actual (as a percent)       13.66% 14.88%
Minimum Capital Requirement (as a percent)       4.00% 4.00%
Minimum To Be Well Capitalized (as a percent)       6.00% 6.00%
Tier 1 Capital (to Average Assets), Amount          
Actual       355,166,000 364,625,000
Minimum Capital Requirement       140,677,000 136,818,000
Minimum To Be Well Capitalized       $ 175,846,000 $ 171,023,000
Tier 1 Capital (to Average Assets), Ratio          
Actual (as a percent)       10.10% 10.66%
Minimum Capital Requirement (as a percent)       4.00% 4.00%
Minimum To Be Well Capitalized (as a percent)       5.00% 5.00%