Quarterly Results of Operations (Unaudited) (Details) - Quarterly Results of Operations for the Operating Partnership - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Results of Operations (Unaudited) (Details) - Quarterly Results of Operations for the Operating Partnership [Line Items]
Total revenues	$ 63,070	$ 59,354	$ 58,671	$ 56,094	$ 51,285	$ 50,077	$ 46,215	$ 45,122	$ 237,189	$ 192,699	$ 155,864
Net income attributable to the Operating Partnership	$ 10,652	$ 8,215	$ 8,638	$ 8,925	$ 7,468	$ 7,837	$ 5,411	$ 4,376	$ 36,430	$ 25,092	$ 21,050
Earnings per share/unit - basic and diluted (in usd per share)	$ 0.09	$ 0.07	$ 0.08	$ 0.08	$ 0.07	$ 0.08	$ 0.05	$ 0.04	$ 0.31	$ 0.25	$ 0.24
Retail Opportunity Investments Partnership L.P.
Quarterly Results of Operations (Unaudited) (Details) - Quarterly Results of Operations for the Operating Partnership [Line Items]
Total revenues	$ 63,070	$ 59,354	$ 58,671	$ 56,094	$ 51,285	$ 50,077	$ 46,215	$ 45,122	$ 237,189	$ 192,699	$ 155,864
Net income attributable to the Operating Partnership	$ 10,652	$ 8,215	$ 8,638	$ 8,925	$ 7,468	$ 7,837	$ 5,411	$ 4,376	$ 36,430	$ 25,092	$ 21,050
Earnings per share/unit - basic and diluted (in usd per share)	$ 0.09	$ 0.07	$ 0.08	$ 0.08	$ 0.07	$ 0.08	$ 0.05	$ 0.04	$ 0.31	$ 0.25	$ 0.24