Document and Entity Information - USD ($)	3 Months Ended
	Mar. 31, 2017	May 09, 2017	Jun. 30, 2016
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			$ 199,087,000
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Entity Common Stock, Shares Outstanding		12,488,787
Document Period End Date	Mar. 31, 2017