Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 27, 2020	Jun. 30, 2019
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2019
Entity File Number	0-15950
Entity Registrant Name	FIRST BUSEY CORPORATION
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	37-1078406
Entity Address, Address Line One	100 W. University Avenue
Entity Address, City or Town	Champaign
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	61820
City Area Code	217
Local Phone Number	365-4544
Title of 12(b) Security	Common Stock ($0.001 par value)
Trading Symbol	BUSE
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 1.3
Entity Common Stock, Shares Outstanding		54,541,061
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0000314489
Amendment Flag	false