Consolidated Statement of Partners' Capital - USD ($) $ in Thousands		Total	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, 2017					11,678,991	[1]			112,347,451	[2]
Balance at Dec. 31, 2017			$ 1,329,641		$ 125,674	[1]			$ 1,202,111	[2]			$ 1,856
Increase (Decrease) in Partners' Capital [Roll Forward]
OP units issued under the Equity Incentive Plan (in shares)	[2]								373,861
OP Units issued under the Equity Incentive Plan		$ 0	0						$ 0	[2]
OP Units withheld for employee taxes (in shares)	[2]								(70,168)
OP Units withheld for employee taxes		(1,400)	(1,400)						$ (1,400)	[2]
Cancellation of OP Units (in shares)	[2]								(4,999)
Cancellation of OP Units			0						$ 0	[2]
Stock based compensation expense		1,428	1,428						1,428	[2]
Adjustment to non-controlling interests ownership in Operating Partnership					191	[1]			$ (191)	[2]
Issuance of OP Units in connection with sale of common stock (in shares)	[2]								75,314
Issuance of OP Units in connection with sale of common stock		1,508	1,508						$ 1,508	[2]
Registration expenditures		(48)	(48)						(48)	[2]
Cash distributions			(24,258)	$ (72)	(2,277)	[1]			(21,981)	[2]	$ (72)	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP			11,824		$ 1,122	[1]			$ 10,702	[2]
Other comprehensive income (loss)		3,808	3,808										3,808
Balance (in shares) at Mar. 31, 2018					11,678,991	[1]			112,721,459	[2]
Balance at Mar. 31, 2018			1,322,431		$ 124,710	[1]			$ 1,192,057	[2]			5,664
Balance (in shares) at Dec. 31, 2017					11,678,991	[1]			112,347,451	[2]
Balance at Dec. 31, 2017			1,329,641		$ 125,674	[1]			$ 1,202,111	[2]			1,856
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income attributable to Retail Opportunity Investments Partnership, LP		35,573	35,573
Balance (in shares) at Sep. 30, 2018					11,574,041				113,984,835
Balance at Sep. 30, 2018			1,325,583		$ 122,734				$ 1,194,869				7,980
Balance (in shares) at Mar. 31, 2018					11,678,991	[1]			112,721,459	[2]
Balance at Mar. 31, 2018			1,322,431		$ 124,710	[1]			$ 1,192,057	[2]			5,664
Increase (Decrease) in Partners' Capital [Roll Forward]
Cancellation of OP Units (in shares)	[2]								(2,000)
Cancellation of OP Units			0						$ 0	[2]
Stock based compensation expense		1,991	1,991						1,991	[2]
Cash redemption of OP Units (in units)	[1]				(30,889)
Cash redemption for non-controlling interests		(560)	(560)		$ (560)	[1]
Adjustment to non-controlling interests ownership in Operating Partnership					522	[1]			(522)	[2]
Registration expenditures		(70)	(70)						(70)	[2]
Cash distributions			(24,256)	(88)	(2,276)	[1]			(21,980)	[2]	(88)	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP			8,102		$ 763	[1]			$ 7,339	[2]
Other comprehensive income (loss)		1,571	1,571										1,571
Balance (in shares) at Jun. 30, 2018					11,648,102	[1]			112,719,459	[2]
Balance at Jun. 30, 2018			1,309,121		$ 123,159	[1]			$ 1,178,727	[2]			7,235
Increase (Decrease) in Partners' Capital [Roll Forward]
OP units issued under the Equity Incentive Plan (in shares)									14,000
OP Units issued under the Equity Incentive Plan		145	145						$ 145
Stock based compensation expense		1,996	1,996						1,996
Cash redemption of OP Units (in units)					(74,061)
Cash redemption for non-controlling interests		(1,432)	(1,432)		$ (1,432)
Adjustment to non-controlling interests ownership in Operating Partnership					1,816				$ (1,816)
Issuance of OP Units in connection with sale of common stock (in shares)									1,251,376
Issuance of OP Units in connection with sale of common stock		24,195	24,195						$ 24,195
Registration expenditures		(258)	(258)						(258)
Cash distributions			(24,489)	(87)	(2,262)				(22,227)		(87)
Net income attributable to Retail Opportunity Investments Partnership, LP		15,647	15,647		$ 1,453				$ 14,194
Other comprehensive income (loss)		745	745										745
Balance (in shares) at Sep. 30, 2018					11,574,041				113,984,835
Balance at Sep. 30, 2018			1,325,583		$ 122,734				$ 1,194,869				7,980
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)	[2]								445,022
OP Units issued under the Equity Incentive Plan		0	0						$ 0	[2]
OP Units withheld for employee taxes (in shares)	[2]								(125,072)
OP Units withheld for employee taxes		(1,986)	(1,986)						$ (1,986)	[2]
Cancellation of OP Units (in shares)	[2]								(999)
Cancellation of OP Units			0						$ 0	[2]
Stock based compensation expense		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]
Adjustment to non-controlling interests ownership in Operating Partnership					(56)	[1]			56	[2]
Registration expenditures		(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 income (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]
Net income attributable to Retail Opportunity Investments Partnership, LP		$ 42,557	42,557
Balance (in shares) at Sep. 30, 2019		126,551,696			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)	[2]								(3,999)
Cancellation of OP Units			0						$ 0	[2]
Stock based compensation expense		$ 2,239	2,239		387	[1]			1,852	[2]
Adjustment to non-controlling interests ownership in Operating Partnership					(592)	[1]			592	[2]
Registration expenditures		(33)	(33)						(33)	[2]
Cash distributions			(24,764)	(65)	(2,247)	[1]	$ (74)	[1]	(22,517)	[2]	9	[2]
Net income attributable to Retail Opportunity Investments Partnership, LP			8,346		$ 761	[1]			$ 7,585	[2]
Other comprehensive income (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
OP Units issued under the Equity Incentive Plan		512	512						$ 512
Cancellation of OP Units (in shares)									(1,999)
Cancellation of OP Units			0						$ 0
Stock based compensation expense		2,234	2,234		$ 314				1,920
Cash redemption of OP Units (in units)					(100,000)
Cash redemption for non-controlling interests		(1,782)	(1,782)		$ (1,782)
Adjustment to non-controlling interests ownership in Operating Partnership					1,780				$ (1,780)
Issuance of OP Units in connection with sale of common stock (in shares)									888,865
Issuance of OP Units in connection with sale of common stock		16,351	16,351						$ 16,351
Registration expenditures		(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 income (loss)		$ (1,322)	(1,322)										(1,322)
Balance (in shares) at Sep. 30, 2019		126,551,696			11,227,041				115,324,655
Balance at Sep. 30, 2019			$ 1,285,152		$ 114,578				$ 1,176,223				$ (5,649)

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

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