Consolidated Statement of Partners' Capital - USD ($) $ in Thousands		Total		Officer [Member]	Retail Opportunity Investments Partnership L.P.	Retail Opportunity Investments Partnership L.P. Officer [Member]	Retail Opportunity Investments Partnership L.P. Limited Partner’s Capital		Retail Opportunity Investments Partnership L.P. ROIC Capital		Retail Opportunity Investments Partnership L.P. ROIC Capital Officer [Member]	[2]	Retail Opportunity Investments Partnership L.P. Accumulated other comprehensive loss	Two Thousand and Nine Stock Plan [Member] Retail Opportunity Investments Partnership L.P. ROIC Capital	Common Stock Retail Opportunity Investments Partnership L.P.	Common Stock Retail Opportunity Investments Partnership L.P. ROIC Capital	[2]
Increase (Decrease) in Partners' Capital [Roll Forward]
Total (in shares)							12,195,603	[1]	99,531,034	[2]
Balance (in shares) at Dec. 31, 2015							12,195,603	[1]	99,531,034	[2]
Balance at Dec. 31, 2015					$ 1,131,342		$ 94,671	[1]	$ 1,043,414	[2]			$ (6,743)
Increase (Decrease) in Partners' Capital [Roll Forward]
OP units issued under the 2009 Plan (in shares)	[2]													337,556
Repurchase of OP Units (in shares)	[2]								(76,262)
Repurchase of OP Units		$ (1,368)			(1,368)				$ (1,368)	[2]
Cancellation of restricted stock (in shares)	[2]								(7,332)
Stock based compensation expense		3,650			3,650				$ 3,650	[2]
Issuance of OP Units (in shares)							2,434,833	[1]								8,757,254
Issuance of OP Units		$ 48,175			48,175		$ 48,175	[1]
Equity redemption of OP Units (in shares)		613,762					(613,762)	[1]	613,762	[2]
OP Unit redemption		$ 12,982			12,982		$ (12,982)	[1]	$ 12,982	[2]
Cash redemption of OP Units (in shares)	[1]						(2,206,613)
Cash redemption of OP Units		(7,182)			(7,182)		$ (7,182)	[1]
Adjustment to non-controlling interests ownership in Operating Partnership		0					3,940	[1]	(3,940)	[2]
Issuance of OP Units in connection with sale of common stock		184,881													$ 184,881	$ 184,881
Registration expenditures		(7,076)			(7,076)				(7,076)	[2]
Cash distributions ($0.54 per unit)					(62,125)		(6,262)	[1]	(55,863)	[2]
Dividends payable to officers		(62,125)		$ (133)		$ (133)					$ (133)
Net income attributable to Retail Opportunity Investments Partnership, LP		25,778			25,778		$ 2,645	[1]	$ 23,133	[2]
Other comprehensive income		$ 1,459			1,459								1,459
Total (in shares)		120,966,073	[2]				12,195,603	[1]	99,531,034	[2]
Proceeds on repayment of promissory note receivable secured by capital		$ 6,710			6,710		$ 6,710	[1]
Balance (in shares) at Sep. 30, 2016		120,966,073	[2]				11,810,061.000	[1]	109,156,012	[2]
Balance at Sep. 30, 2016					1,324,111		$ 129,715	[1]	$ 1,199,680	[2]			(5,284)
Increase (Decrease) in Partners' Capital [Roll Forward]
Total (in shares)		120,966,073	[2]				11,810,061.000	[1]	109,156,012	[2]
Total					$ 1,317,401		$ 123,005	[1]	$ 1,199,680	[2]			$ (5,284)

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

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