Reportable Segments and Related Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 item	Sep. 30, 2012	Dec. 31, 2012
Reportable Segments and Related Information
Number of reportable segments			3
Reportable Segments and Related Information
Goodwill	$ 20,686		$ 20,686		$ 20,686
Total Assets	3,532,024		3,532,024		3,618,056
Interest Income:	27,236	29,011	81,811	88,332
Interest Expense:	2,003	3,466	6,750	11,815
Other Income:	15,630	15,589	48,054	49,239
Net Income:	7,933	4,909	21,806	17,440
Operating segments | Busey Bank
Reportable Segments and Related Information
Total Assets	3,448,907		3,448,907		3,567,637
Interest Income:	27,167	28,935	81,597	88,093
Interest Expense:	1,709	3,138	5,858	10,828
Other Income:	9,447	9,850	29,542	29,592
Net Income:	6,963	4,642	19,243	14,859
Operating segments | FirsTech
Reportable Segments and Related Information
Goodwill	8,992		8,992		8,992
Total Assets	26,946		26,946		26,401
Interest Income:	13	15	39	48
Other Income:	2,167	2,094	6,445	6,418
Net Income:	259	237	807	746
Operating segments | Busey Wealth Management
Reportable Segments and Related Information
Goodwill	11,694		11,694		11,694
Total Assets	27,855		27,855		26,653
Interest Income:	62	62	179	192
Other Income:	4,540	4,061	13,286	12,332
Net Income:	1,173	780	3,126	2,647
Operating segments | All Other
Reportable Segments and Related Information
Total Assets	28,316		28,316		(2,635)
Interest Income:	(6)	(1)	(4)	(1)
Interest Expense:	294	328	892	987
Other Income:	(524)	(416)	(1,219)	897
Net Income:	$ (462)	$ (750)	$ (1,370)	$ (812)