Organization, Basis of Presentation and Summary of Significant Accounting Policies (Reconciliation Between Basic and Diluted EPS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income	$ 11,251	$ 8,925
Net income attributable to non-controlling interests	1,081	898
Less earnings allocated to unvested shares	(80)	(68)
Net income available for common stockholders, basic	10,090	7,959
Less earnings allocated to unvested shares	(80)	(68)
Net income available for common stockholders, diluted	$ 11,171	$ 8,857
Denominator:
Denominator for basic EPS – weighted average common equivalent shares (in shares)	109,226,809	99,410,942
Denominator for diluted EPS – weighted average common equivalent shares (in shares)	121,054,051	110,711,490
Retail Opportunity Investments Partnership L.P.
Numerator:
Net income	$ 11,251	$ 8,925
Less earnings allocated to unvested shares	(80)	(68)
Net income available to unitholders, basic and diluted	$ 11,171	$ 8,857
Denominator:
Denominator for basic EPS – weighted average common equivalent shares (in shares)	120,795,980	110,504,812
Denominator for diluted EPS – weighted average common equivalent shares (in shares)	121,054,051	110,711,490
OP units
Denominator:
OP units (in shares)	11,569,171	11,093,870
Restricted stock awards – performance-based
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	122,234	88,618
Restricted stock awards – performance-based | Retail Opportunity Investments Partnership L.P.
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	122,234	88,618
Stock options
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	135,837	118,060
Stock options | Retail Opportunity Investments Partnership L.P.
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	135,837	118,060