Real Estate Investments (Operating Results Included in the Company's Historical Consolidated Statement of Operations for Properties Acquired During the Reported Periods) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Business Acquisition [Line Items]
Revenues	$ 3,067
Net income attributable to Retail Opportunity Investments Corp.	$ 818
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Revenues		$ 3,396
Net income attributable to Retail Opportunity Investments Corp.		$ 893