Document and Entity Information - USD ($)	9 Months Ended
	Sep. 30, 2015	Nov. 06, 2015	Jun. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	FIRST MID ILLINOIS BANCSHARES INC
Entity Central Index Key	0000700565
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 107,610,000
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Entity Common Stock, Shares Outstanding		8,974,818
Document Period End Date	Sep. 30, 2015