Regulatory Capital (Details) - USD ($) $ in Thousands	Jun. 02, 2022	May 25, 2017	Jun. 30, 2022	Dec. 31, 2021
Common Equity Tier 1 Capital to Risk Weighted Assets, Amount
Actual, Amount			$ 1,031,356	$ 995,874
Minimum Capital Requirement, Amount			394,196	378,334
Minimum To Be Well Capitalized, Amount			$ 569,394	$ 546,482
Common Equity Tier 1 Capital to Risk Weighted Assets, Ratio
Actual, Ratio (as a percent)			11.77%	11.85%
Minimum Capital Requirement, Ratio (as a percent)			4.50%	4.50%
Minimum To Be Well Capitalized, Ratio (as a percent)			6.50%	6.50%
Tier 1 Capital to Risk Weighted Assets, Amount
Actual, Amount			$ 1,105,356	$ 1,069,874
Minimum Capital Requirement, Amount			525,594	504,445
Minimum To Be Well Capitalized, Amount			$ 700,792	$ 672,594
Tier 1 Capital to Risk Weighted Assets, Ratio
Actual, Ratio (as a percent)			12.62%	12.73%
Minimum Capital Requirement, Ratio (as a percent)			6.00%	6.00%
Minimum To Be Well Capitalized, Ratio (as a percent)			8.00%	8.00%
Total Capital to Risk Weighted Assets, Amount
Actual, Amount			$ 1,452,813	$ 1,320,187
Minimum Capital Requirement, Amount			700,792	672,594
Minimum To Be Well Capitalized, Amount			$ 875,990	$ 840,742
Total Capital to Risk Weighted Assets, Ratio
Actual, Ratio (as a percent)			16.58%	15.70%
Minimum Capital Requirement, Ratio (as a percent)			8.00%	8.00%
Minimum To Be Well Capitalized, Ratio (as a percent)			10.00%	10.00%
Leverage Ratio of Tier 1 Capital to Average Assets, Amount
Actual, Amount			$ 1,105,356	$ 1,069,874
Minimum Capital Requirement, Amount			$ 489,513	$ 502,336
Leverage Ratio of Tier 1 Capital to Average Assets, Ratio
Actual, Ratio (as a percent)			9.03%	8.52%
Minimum Capital Requirement, Ratio (as a percent)			4.00%	4.00%
Busey Bank
Common Equity Tier 1 Capital to Risk Weighted Assets, Amount
Actual, Amount			$ 1,265,418	$ 1,241,303
Minimum Capital Requirement, Amount			392,637	377,096
Minimum To Be Well Capitalized, Amount			$ 567,142	$ 544,695
Common Equity Tier 1 Capital to Risk Weighted Assets, Ratio
Actual, Ratio (as a percent)			14.50%	14.81%
Minimum Capital Requirement, Ratio (as a percent)			4.50%	4.50%
Minimum To Be Well Capitalized, Ratio (as a percent)			6.50%	6.50%
Tier 1 Capital to Risk Weighted Assets, Amount
Actual, Amount			$ 1,265,418	$ 1,241,303
Minimum Capital Requirement, Amount			523,516	502,795
Minimum To Be Well Capitalized, Amount			$ 698,021	$ 670,394
Tier 1 Capital to Risk Weighted Assets, Ratio
Actual, Ratio (as a percent)			14.50%	14.81%
Minimum Capital Requirement, Ratio (as a percent)			6.00%	6.00%
Minimum To Be Well Capitalized, Ratio (as a percent)			8.00%	8.00%
Total Capital to Risk Weighted Assets, Amount
Actual, Amount			$ 1,339,875	$ 1,306,616
Minimum Capital Requirement, Amount			698,021	670,394
Minimum To Be Well Capitalized, Amount			$ 872,526	$ 837,992
Total Capital to Risk Weighted Assets, Ratio
Actual, Ratio (as a percent)			15.36%	15.59%
Minimum Capital Requirement, Ratio (as a percent)			8.00%	8.00%
Minimum To Be Well Capitalized, Ratio (as a percent)			10.00%	10.00%
Leverage Ratio of Tier 1 Capital to Average Assets, Amount
Actual, Amount			$ 1,265,418	$ 1,241,303
Minimum Capital Requirement, Amount			488,139	501,104
Minimum To Be Well Capitalized, Amount			$ 610,174	$ 626,379
Leverage Ratio of Tier 1 Capital to Average Assets, Ratio
Actual, Ratio (as a percent)			10.37%	9.91%
Minimum Capital Requirement, Ratio (as a percent)			4.00%	4.00%
Minimum To Be Well Capitalized, Ratio (as a percent)			5.00%	5.00%
Subordinated debt | Fixed-to-floating rate notes due 2027
Regulatory Capital
Redemption amount		$ 60,000
Term of debt instrument		5 years
Subordinated debt | Fixed-to-floating rate notes due 2032
Regulatory Capital
Principal balance	$ 100,000
Fixed to floating interest rate (as a percent)	5.00%