Capital of the Operating Partnership (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017
Limited Partners' Capital Account [Line Items]
Partnership units (in shares)	126,551,696	126,551,696
ROIC ownership percentage in ROIP LP		91.10%
Common stock, shares outstanding (in shares)	115,324,655	115,324,655					113,992,837
Minority interest increase (decrease) from redemptions number of units (in shares)		250,000
Equity redemption of OP Units, cash (in shares)		170,000
Equity redemption of OP Units cash dollars		$ 3,000
Equity redemption of OP units (in shares)		80,000
Common Stock
Limited Partners' Capital Account [Line Items]
Common stock, shares outstanding (in shares)	115,324,655	115,324,655	114,307,789		114,311,788		113,992,837		113,984,835	112,719,459		112,721,459		112,347,451
Equity redemption of OP units (in shares)	80,000	80,000
OP Units
Limited Partners' Capital Account [Line Items]
Non-controlling interest redemption value	$ 205,500	$ 205,500
Redemption value (usd per share)	$ 18.30	$ 18.30
Retail Opportunity Investments Partnership L.P.
Limited Partners' Capital Account [Line Items]
Equity redemption of OP Units cash dollars	$ (1,472)
Equity redemption of OP units (in shares)	80,000
Limited Partner’s Capital | Retail Opportunity Investments Partnership L.P.
Limited Partners' Capital Account [Line Items]
Partnership units (in shares)	11,227,041	11,227,041	11,407,041	[1]	11,407,041	[1]	11,477,041	[1]	11,574,041	11,648,102	[1]	11,678,991	[1]	11,678,991	[1]
Equity redemption of OP Units cash dollars	$ 1,472
Equity redemption of OP units (in shares)	80,000

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