Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 28, 2018
Document And Entity Information
Entity Registrant Name	INCOME OPPORTUNITY REALTY INVESTORS INC /TX/
Entity Central Index Key	0000949961
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Trading Symbol	IOR
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity a Well-known Seasoned Issuer	No
Entity a Voluntary Filer	No
Entity's Reporting Status Current	Yes
Entity Filer Category	Smaller Reporting Company
Entity Public Float	$ 5,546,832
Entity Common Stock, Shares Outstanding		4,168,214
Entity Common Stock, Shares held by Nonaffiliates	781,244
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2017