Organization, Basis of Presentation and Summary of Significant Accounting Policies (Details) - Reconciliation Between Basic and Diluted EPS - USD ($) $ 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
Numerator:
Net income	$ 10,652	$ 8,215	$ 8,638	$ 8,925	$ 7,468	$ 7,837	$ 5,411	$ 4,376	$ 36,430	$ 25,092	$ 21,050
Less income attributable to non-controlling interests									(3,676)	(1,228)	(749)
Less earnings allocated to unvested shares, basic									(270)	(229)	(160)
Less earnings allocated to unvested shares, diluted									(270)	(229)	(160)
Net income available to common stockholders, basic									32,484	23,635	20,141
Net income available to common stockholders, diluted									$ 36,160	$ 24,863	$ 20,890
Denominator:
Denominator for basic EPS – weighted average common equivalent shares (in shares)									104,072,222	95,651,780	83,411,230
OP Units (in shares)									11,747,509	4,086,724	3,162,658
Denominator for diluted EPS – weighted average common equivalent shares (in shares)									116,039,940	100,017,781	87,453,409
Warrant
Denominator:
Warrants (in shares)									0	0	631,086
Retail Opportunity Investments Partnership L.P.
Numerator:
Net income	$ 10,652	$ 8,215	$ 8,638	$ 8,925	$ 7,468	$ 7,837	$ 5,411	$ 4,376	$ 36,430	$ 25,092	$ 21,050
Less earnings allocated to unvested shares, basic									(270)	(229)	(160)
Net income available to unitholders, basic and diluted									$ 36,160	$ 24,863	$ 20,890
Denominator:
Denominator for basic EPS – weighted average common equivalent shares (in shares)									115,819,731	99,738,504	86,573,888
Denominator for diluted EPS – weighted average common equivalent shares (in shares)									116,039,940	100,017,781	87,453,409
Retail Opportunity Investments Partnership L.P. | Warrant
Denominator:
Warrants (in shares)									0	0	631,086
Restricted stock awards – performance-based
Denominator:
Restricted units and stock options (in shares)									86,996	174,198	162,327
Restricted stock awards – performance-based | Retail Opportunity Investments Partnership L.P.
Denominator:
Restricted units and stock options (in shares)									86,996	174,198	162,327
Stock options
Denominator:
Restricted units and stock options (in shares)									133,213	105,079	86,108
Stock options | Retail Opportunity Investments Partnership L.P.
Denominator:
Restricted units and stock options (in shares)									133,213	105,079	86,108