Organization, Basis of Presentation and Summary of Significant Accounting Policies (Reconciliation Between Basic and Diluted EPS) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 8,638	$ 5,411	$ 17,563	$ 9,787
Net income attributable to non-controlling interests	934	210	1,832	386
Less earnings allocated to unvested shares	(68)	(57)	(136)	(115)
Net income available for common stockholders, basic	7,636	5,144	15,595	9,286
Less earnings allocated to unvested shares	(68)	(57)	(136)	(115)
Net income available for common stockholders, diluted	$ 8,570	$ 5,354	$ 17,427	$ 9,672
Denominator for basic EPS – weighted average common equivalent shares (in shares)	100,166,136	93,586,398	99,788,706	93,339,158
Denominator for diluted EPS – weighted average common equivalent shares (in shares)	112,642,901	97,612,225	111,688,972	97,425,385
Retail Opportunity Investments Partnership L.P.
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 8,638	$ 5,411	$ 17,563	$ 9,787
Less earnings allocated to unvested shares	$ (68)	$ (57)	$ (136)	$ (115)
Denominator for basic EPS – weighted average common equivalent shares (in shares)	112,358,245	97,372,547	111,431,696	97,192,516
Denominator for diluted EPS – weighted average common equivalent shares (in shares)	112,642,901	97,612,225	111,688,972	97,425,385
Net income available to unitholders, basic and diluted	$ 8,570	$ 5,354	$ 17,427	$ 9,672
OP units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
OP units (in shares)	12,192,109	3,786,149	11,642,990	3,853,358
Restricted stock awards – performance-based
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	152,675	139,096	131,783	127,964
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	131,981	100,582	125,493	104,905