Consolidated Statement of Partners' Capital - USD ($) $ in Thousands		Total	Common Stock	Non- controlling interests	Additional paid-in capital	Retail Opportunity Investments Partnership L.P.	Retail Opportunity Investments Partnership L.P. Officer	Retail Opportunity Investments Partnership L.P. Limited Partner’s Capital		Retail Opportunity Investments Partnership L.P. Limited Partner’s Capital Officer		Retail Opportunity Investments Partnership L.P. ROIC Capital		Retail Opportunity Investments Partnership L.P. ROIC Capital Officer		Retail Opportunity Investments Partnership L.P. Accumulated other comprehensive income (loss)
Balance (in shares) at Dec. 31, 2018								11,477,041	[1]			113,992,837	[2]
Balance at Dec. 31, 2018						$ 1,308,428		$ 120,214	[1]			$ 1,184,653	[2]			$ 3,561
Increase (Decrease) in Partners' Capital [Roll Forward]
OP units issued under the Equity Incentive Plan (in shares)			445,022									445,022	[2]
OP Units issued under the Equity Incentive Plan		$ 0			$ 0	0						$ 0	[2]
OP Units withheld for employee taxes (in shares)			(125,072)									(125,072)	[2]
OP Units withheld for employee taxes		(1,986)			(1,986)	(1,986)						$ (1,986)	[2]
Cancellation of OP Units (in shares)			(999)									(999)	[2]
Stock based compensation expense		1,651			1,651	1,651						$ 1,651	[2]
Cash redemption of OP Units (in units)	[1]							(70,000)
Cash redemption for non-controlling interests		(1,246)		$ (1,246)		(1,246)		$ (1,246)	[1]
Adjustment to non-controlling interests ownership in Operating Partnership				(56)	56			(56)	[1]			56	[2]
Registration expenditures		(47)			(47)	(47)						(47)	[2]
Cash distributions						(24,766)	$ 142	(2,247)	[1]			(22,519)	[2]	$ 142	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP						14,583		$ 1,333	[1]			$ 13,250	[2]
Other comprehensive gain (loss)		(2,810)				(2,810)										(2,810)
Balance (in shares) at Mar. 31, 2019								11,407,041	[1]			114,311,788	[2]
Balance at Mar. 31, 2019						1,293,949		$ 117,998	[1]			$ 1,175,200	[2]			751
Balance (in shares) at Dec. 31, 2018								11,477,041	[1]			113,992,837	[2]
Balance at Dec. 31, 2018						1,308,428		$ 120,214	[1]			$ 1,184,653	[2]			3,561
Increase (Decrease) in Partners' Capital [Roll Forward]
Redemption of OP Units		1,472				1,472
Net income attributable to Retail Opportunity Investments Partnership, LP		42,557				42,557
Balance (in shares) at Sep. 30, 2019								11,227,041				115,324,655
Balance at Sep. 30, 2019						1,285,152		$ 114,578				$ 1,176,223				(5,649)
Balance (in shares) at Mar. 31, 2019								11,407,041	[1]			114,311,788	[2]
Balance at Mar. 31, 2019						1,293,949		$ 117,998	[1]			$ 1,175,200	[2]			751
Increase (Decrease) in Partners' Capital [Roll Forward]
Cancellation of OP Units (in shares)			(3,999)									(3,999)	[2]
Stock based compensation expense		2,239		387	1,852	2,239		387				$ 1,852	[2]
Adjustment to non-controlling interests ownership in Operating Partnership				(592)	592			(592)	[1]			592	[2]
Registration expenditures		(33)			(33)	(33)						(33)	[2]
Cash distributions						(24,764)	(65)	(2,247)	[1]	$ (74)		(22,517)	[2]	9	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP						8,346		$ 761	[1]			$ 7,585	[2]
Other comprehensive gain (loss)		(5,078)				(5,078)										(5,078)
Balance (in shares) at Jun. 30, 2019								11,407,041	[1]			114,307,789	[2]
Balance at Jun. 30, 2019						1,274,594		$ 116,233	[1]			$ 1,162,688	[2]			(4,327)
Increase (Decrease) in Partners' Capital [Roll Forward]
OP units issued under the Equity Incentive Plan (in shares)			50,000									50,000
OP Units issued under the Equity Incentive Plan		512			512	512						$ 512
Cancellation of OP Units (in shares)			(1,999)									(1,999)
Stock based compensation expense		2,234		314	1,920	2,234		$ 314				$ 1,920
Equity Redemption of OP Units (in shares)			80,000					80,000				80,000
Redemption of OP Units				(1,472)	1,472			$ (1,472)				$ 1,472
Cash redemption of OP Units (in units)								(100,000)
Cash redemption for non-controlling interests		(1,782)		(1,782)		(1,782)		$ (1,782)
Adjustment to non-controlling interests ownership in Operating Partnership				1,780	(1,780)			1,780				$ (1,780)
Issuance of OP Units in connection with sale of common stock, Units			888,865									888,865
Issuance of OP Units in connection with sale of common stock		16,351	$ 1		16,350	16,351						$ 16,351
Registration expenditures		(207)			(207)	(207)						(207)
Cash distributions						(24,792)	(64)	(2,228)		(37)		(22,564)		(27)
Net income attributable to Retail Opportunity Investments Partnership, LP		19,628				19,628		$ 1,770				$ 17,858
Other comprehensive gain (loss)		(1,322)				(1,322)										(1,322)
Balance (in shares) at Sep. 30, 2019								11,227,041				115,324,655
Balance at Sep. 30, 2019						1,285,152		$ 114,578				$ 1,176,223				(5,649)
Balance (in shares) at Dec. 31, 2019								11,051,090	[1]			116,496,016	[2]
Balance at Dec. 31, 2019						1,291,828		$ 112,480	[1]			$ 1,183,480	[2]			(4,132)
Increase (Decrease) in Partners' Capital [Roll Forward]
OP units issued under the Equity Incentive Plan (in shares)			428,170									428,170	[2]
OP Units issued under the Equity Incentive Plan		0			0	0						$ 0	[2]
OP Units withheld for employee taxes (in shares)			(128,614)									(128,614)	[2]
OP Units withheld for employee taxes		(2,272)			(2,272)	(2,272)						$ (2,272)	[2]
Cancellation of OP Units (in shares)			(1,000)									(1,000)	[2]
Stock based compensation expense		1,856		220	1,636	1,856		$ 220	[1]			$ 1,636	[2]
Cash redemption of OP Units (in units)	[1]							(116,657)
Cash redemption for non-controlling interests		(1,999)		(1,999)		(1,999)		$ (1,999)	[1]
Adjustment to non-controlling interests ownership in Operating Partnership				(652)	652			(652)	[1]			$ 652	[2]
Repurchase of OP units (in shares)			(673,868)									(673,868)	[2]
Repurchase of OP Units		(8,846)			(8,846)							$ (8,846)	[2]
Registration expenditures		(90)			(90)	(90)						(90)	[2]
Cash distributions						(25,460)	$ (89)	(2,187)	[1]	$ (33)	[1]	(23,273)	[2]	$ (56)	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP						13,136		$ 1,134	[1]			$ 12,002	[2]
Other comprehensive gain (loss)		$ (8,717)				(8,717)										(8,717)
Balance (in shares) at Mar. 31, 2020								10,934,433	[1]			116,120,704	[2]
Balance at Mar. 31, 2020						1,259,347		$ 108,963	[1]			$ 1,163,233	[2]			(12,849)
Balance (in shares) at Dec. 31, 2019								11,051,090	[1]			116,496,016	[2]
Balance at Dec. 31, 2019						1,291,828		$ 112,480	[1]			$ 1,183,480	[2]			(4,132)
Increase (Decrease) in Partners' Capital [Roll Forward]
Equity Redemption of OP Units (in shares)		1,823,350	1,823,350
Redemption of OP Units		$ 18,287				18,287
Repurchase of OP units (in shares)		(673,868)
Repurchase of OP Units		$ (8,800)
Net income attributable to Retail Opportunity Investments Partnership, LP		$ 25,141				25,141
Balance (in shares) at Sep. 30, 2020		127,051,238						9,111,083				117,940,155
Balance at Sep. 30, 2020						1,277,674		$ 92,910				$ 1,195,789				(11,025)
Balance (in shares) at Mar. 31, 2020								10,934,433	[1]			116,120,704	[2]
Balance at Mar. 31, 2020						1,259,347		$ 108,963	[1]			$ 1,163,233	[2]			(12,849)
Increase (Decrease) in Partners' Capital [Roll Forward]
Cancellation of OP Units (in shares)			(2,499)									(2,499)	[2]
Stock based compensation expense		$ 2,168		87	2,081	2,168		$ 87	[1]			$ 2,081	[2]
Equity Redemption of OP Units (in shares)			1,521,833					1,521,833				1,521,833
Redemption of OP Units				(15,211)	15,211	15,211		$ (15,211)
Adjustment to non-controlling interests ownership in Operating Partnership				1,064	(1,064)			1,064	[1]			$ (1,064)	[2]
Registration expenditures		6			6	6						6	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP						5,036		$ 389	[1]			$ 4,647	[2]
Other comprehensive gain (loss)		264		(937)		264										264
Balance (in shares) at Jun. 30, 2020								9,412,600	[1]			117,640,038	[2]
Balance at Jun. 30, 2020						1,266,821		$ 95,292	[1]			$ 1,184,114	[2]			(12,585)
Increase (Decrease) in Partners' Capital [Roll Forward]
Cancellation of OP Units (in shares)			(1,400)									(1,400)
Stock based compensation expense		2,341		255	2,086	$ 2,341		$ 255				$ 2,086
Equity Redemption of OP Units (in shares)			301,517			301,517		301,517
Redemption of OP Units				(3,076)	3,076			$ (3,076)				3,076
Adjustment to non-controlling interests ownership in Operating Partnership				(64)	64			(64)				64
Registration expenditures		(17)			$ (17)	$ (17)						(17)
Net income attributable to Retail Opportunity Investments Partnership, LP		6,969				6,969		$ 503				$ 6,466
Other comprehensive gain (loss)		$ 1,560		$ 142		1,560										1,560
Balance (in shares) at Sep. 30, 2020		127,051,238						9,111,083				117,940,155
Balance at Sep. 30, 2020						$ 1,277,674		$ 92,910				$ 1,195,789				$ (11,025)

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

[2] Consists of general and limited partnership interests held by ROIC.