Reportable Segments and Related Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Reportable Segments and Related Information
Number of reportable segments									3
Reportable Segments and Related Information
Goodwill	$ 20,686				$ 20,686				$ 20,686	$ 20,686
Total Assets	3,618,056				3,402,122				3,618,056	3,402,122
Interest Income:	28,584	29,011	29,225	30,096	31,229	32,811	33,873	34,906	116,916	132,819	156,183
Interest Expense:	2,955	3,466	3,951	4,398	4,751	5,084	6,032	6,559	14,770	22,426	39,032
Other Income:	17,613	15,589	15,770	17,880	15,012	14,718	13,746	15,539	66,852	59,015	62,753
Net income (loss)	4,917	4,909	4,888	7,643	5,746	7,570	7,447	9,110	22,357	29,873	23,230
Busey Bank
Reportable Segments and Related Information
Total Assets	3,567,637				3,331,869				3,567,637	3,331,869
Interest Income:									116,608	132,501	155,921
Interest Expense:									13,466	20,514	35,887
Other Income:									39,908	35,940	40,341
Net income (loss)									19,162	28,504	21,230
FirsTech
Reportable Segments and Related Information
Goodwill	8,992				8,992				8,992	8,992
Total Assets	26,401				25,542				26,401	25,542
Interest Income:									62	66	56
Other Income:									8,522	9,287	9,493
Net income (loss)									935	1,437	1,821
Busey Wealth Management
Reportable Segments and Related Information
Goodwill	11,694				11,694				11,694	11,694
Total Assets	26,653				25,867				26,653	25,867
Interest Income:									251	255	248
Other Income:									16,345	14,841	13,822
Net income (loss)									3,363	3,095	3,283
All Other
Reportable Segments and Related Information
Total Assets	(2,635)				18,844				(2,635)	18,844
Interest Income:									(5)	(3)	(42)
Interest Expense:									1,304	1,912	3,145
Other Income:									2,077	(1,053)	(903)
Net income (loss)									$ (1,103)	$ (3,163)	$ (3,104)