Reportable Segments and Related Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012	Dec. 31, 2012
Reportable Segments and Related Information
Number of reportable segments	3
Reportable Segments and Related Information
Goodwill	$ 20,686		$ 20,686
Total Assets	3,648,310		3,618,056
Interest income:	27,115	30,096
Interest expense:	2,532	4,398
Other income:	16,641	17,880
Net income:	6,433	7,643
Busey Bank
Reportable Segments and Related Information
Total Assets	3,571,224		3,567,637
Interest income:	27,040	30,013
Interest expense:	2,232	4,064
Other income:	10,497	10,064
Net income:	5,793	6,029
FirsTech
Reportable Segments and Related Information
Goodwill	8,992		8,992
Total Assets	26,453		26,401
Interest income:	13	16
Other income:	2,129	2,189
Net income:	262	265
Busey Wealth Management
Reportable Segments and Related Information
Goodwill	11,694		11,694
Total Assets	26,523		26,653
Interest income:	60	66
Other income:	4,103	3,932
Net income:	820	863
All Other
Reportable Segments and Related Information
Total Assets	24,110		(2,635)
Interest income:	2	1
Interest expense:	300	334
Other income:	(88)	1,695
Net income:	$ (442)	$ 486