Capital of the Operating Partnership (Details Textual) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Limited Partners' Capital Account [Line Items]
Partnership units (in shares)		127,052,638	127,052,638
Common stock, shares outstanding (in shares)		117,640,038	117,640,038		116,496,016
Minority interest increase (decrease) from redemptions number of units (in shares)			1,638,490
Equity redemption of OP Units, cash (in shares)			116,657
Equity redemption of OP Units cash dollars			$ 2.0
Equity Redemption of OP Units, Shares			1,521,833
ROIC
Limited Partners' Capital Account [Line Items]
ROIC ownership percentage in ROIP LP			92.60%
Common Stock
Limited Partners' Capital Account [Line Items]
Common stock, shares outstanding (in shares)		117,640,038	117,640,038	116,120,704	116,496,016	114,307,789	114,311,788	113,992,837
Equity Redemption of OP Units, Shares		1,521,833	1,521,833
OP Units
Limited Partners' Capital Account [Line Items]
Non-controlling interest redemption value		$ 107.0	$ 107.0
Redemption value (usd per share)		$ 11.37	$ 11.37
Limited Partner’s Capital | Retail Opportunity Investments Partnership L.P.
Limited Partners' Capital Account [Line Items]
Partnership units (in shares)	[1]	9,412,600	9,412,600	10,934,433	11,051,090	11,407,041	11,407,041	11,477,041
Equity Redemption of OP Units, Shares		1,521,833

[1] Consists of limited partnership interests held by third parties.