Note 2 - Real Estate Investments (Details) - Operating Results Included in the Company's Historical Consolidated Statement of Operations for Properties Acquired During the Reported Periods - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statements of operations:
Revenues	$ 50,077	$ 40,856	$ 141,414	$ 114,121
Depreciation and amortization	18,059	15,365	52,567	42,986
Net income attributable to Retail Opportunity Investments Corp.	7,542	$ 6,748	16,943	$ 15,714
Attributable to Acquired Properties During the Reporting Periods [Member]
Statements of operations:
Revenues	3,547		7,567
Property operating and other expenses	1,060		2,162
Depreciation and amortization	1,613		3,574
Net income attributable to Retail Opportunity Investments Corp.	$ 874		$ 1,831