Consolidated Statements of Equity (USD $)	ATM Equity Offering Sales Agreement [Member] Common Stock [Member]	ATM Equity Offering Sales Agreement [Member] Additional Paid-in Capital [Member]	ATM Equity Offering Sales Agreement [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member] Officer [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member] Cash Redemption for Non-controlling Interests [Member]	Noncontrolling Interest [Member] Purchase of Non-controlling Interests [Member]	Noncontrolling Interest [Member]	Cash Redemption for Non-controlling Interests [Member]	Purchase of Non-controlling Interests [Member]	Officer [Member]	Total
Balance at December 31, 2011 at Dec. 31, 2011				$ 4,938	$ 484,194,434		$ (19,617,877)	$ (14,094,830)			$ 2,389				$ 450,489,054
Balance at December 31, 2011 (in Shares) at Dec. 31, 2011				49,375,738
Shares issued under the 2009 Plan				22											22
Shares issued under the 2009 Plan (in Shares)				224,067
Repurchase of common stock				(6)	(708,170)										(708,176)
Repurchase of common stock (in Shares)				(55,496)
Stock based compensation expense					3,393,439										3,393,439
Proceeds from the sale of stock	306	37,811,352	37,811,658
Proceeds from the sale of stock (in Shares)	3,051,445
Registration expenditures					(1,162,787)										(1,162,787)
Proceeds from the exercise of warrants					12,000										12,000
Proceeds from the exercise of warrants (in Shares)				1,000
Cash dividends						(68,475)	(27,057,495)							(68,475)	(27,057,495)
Dividends payable to officers						(68,475)	(27,057,495)							(68,475)	(27,057,495)
Net income attributable to Retail Opportunity Investments Corp.							7,892,613								7,892,613
Other comprehensive loss								(4,059,782)							(4,059,782)
Balance at Dec. 31, 2012				5,260	523,540,268		(38,851,234)	(18,154,612)			2,389				466,542,071
Balance (in Shares) at Dec. 31, 2012				52,596,754
Shares issued under the 2009 Plan				31	(31)
Shares issued under the 2009 Plan (in Shares)				313,364
Repurchase of common stock				(3)	(406,539)										(406,542)
Repurchase of common stock (in Shares)				(30,333)
Retirement of options					(274,830)										(274,830)
Stock based compensation expense					2,856,391										2,856,391
Registration expenditures					(69,245)										(69,245)
Proceeds from the exercise of warrants				1,882	226,527,896										226,529,778
Proceeds from the exercise of warrants (in Shares)				18,877,482
Exercise of Sponsor warrants				68	(68)
Exercise of Sponsor warrants (in Shares)				688,500
Buyback of warrants					(32,785,921)										(32,785,921)
Issuance of OP Units to non-controlling interests											45,372,731				45,372,731
Distributions to non-controlling interests											(277,424)				(277,424)
Decrease in non-controlling interests									(2,189,779)	(2,389)		(2,189,779)	(2,389)
Adjustment to non-controlling interests ownership in Operating Partnership					13,313,937						(13,313,937)
Cash dividends						(110,000)	(42,468,897)				(469,806)			(110,000)	(42,938,703)
Dividends payable to officers						(110,000)	(42,468,897)				(469,806)			(110,000)	(42,938,703)
Net income attributable to Retail Opportunity Investments Corp.							33,813,561								33,813,561
Net income attributable to non-controlling interests											164,892				164,892
Other comprehensive loss								9,185,475							9,185,475
Balance at Dec. 31, 2013				7,238	732,701,858		(47,616,570)	(8,969,137)			29,286,677				705,410,066
Balance (in Shares) at Dec. 31, 2013				72,445,767											72,445,767
Shares issued under the 2009 Plan				34	(34)
Shares issued under the 2009 Plan (in Shares)				340,621
Repurchase of common stock				(4)	(630,891)										(630,895)
Repurchase of common stock (in Shares)				(42,438)											0
Cancellation of restricted stock (in Shares)				(5,833)
Stock based compensation expense					3,662,034										3,662,034
Proceeds from the sale of stock				1,438	214,904,813										214,906,251
Proceeds from the sale of stock (in Shares)			0	14,375,000
Registration expenditures					(9,633,785)										(9,633,785)
Proceeds from the exercise of warrants				587	70,538,004										70,538,591
Proceeds from the exercise of warrants (in Shares)				5,878,216
Issuance of OP Units to non-controlling interests											16,342,775				16,342,775
Decrease in non-controlling interests									(3,280,000)			(3,280,000)
Adjustment to non-controlling interests ownership in Operating Partnership					2,019,444						(2,019,444)
Cash dividends						(137,864)	(53,522,261)				(2,008,636)			(137,864)	(55,530,897)
Dividends payable to officers						(137,864)	(53,522,261)				(2,008,636)			(137,864)	(55,530,897)
Net income attributable to Retail Opportunity Investments Corp.							20,301,045								20,301,045
Net income attributable to non-controlling interests											748,177				748,177
Other comprehensive loss								86,720							86,720
Balance at Dec. 31, 2014				$ 9,293	$ 1,013,561,443		$ (80,975,650)	$ (8,882,417)			$ 39,069,549				$ 962,782,218
Balance (in Shares) at Dec. 31, 2014				92,991,333											92,991,333