Consolidated Statements of Operations and Comprehensive Income (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Base rents	$ 119,841,623	$ 86,194,511	$ 59,218,635
Recoveries from tenants	32,945,321us-gaap_TenantReimbursements	22,497,745us-gaap_TenantReimbursements	13,483,825us-gaap_TenantReimbursements
Mortgage interest		623,793	1,106,089
Other income	3,076,567us-gaap_OtherIncome	1,915,982us-gaap_OtherIncome	1,287,138us-gaap_OtherIncome
Total revenues	155,863,511us-gaap_Revenues	111,232,031us-gaap_Revenues	75,095,687us-gaap_Revenues
Operating expenses
Property operating	25,035,765	19,749,972	12,779,758
Property taxes	15,953,210us-gaap_RealEstateTaxesAndInsurance	11,246,967us-gaap_RealEstateTaxesAndInsurance	7,281,213us-gaap_RealEstateTaxesAndInsurance
Depreciation and amortization	58,434,981	40,397,895	29,074,709
General and administrative expenses	11,199,632us-gaap_GeneralAndAdministrativeExpense	10,058,669us-gaap_GeneralAndAdministrativeExpense	12,734,254us-gaap_GeneralAndAdministrativeExpense
Acquisition transaction costs	961,167us-gaap_AcquisitionCosts	1,688,521us-gaap_AcquisitionCosts	1,347,611us-gaap_AcquisitionCosts
Other expenses	504,828us-gaap_OtherCostAndExpenseOperating	314,833us-gaap_OtherCostAndExpenseOperating	324,354us-gaap_OtherCostAndExpenseOperating
Total operating expenses	112,089,583us-gaap_OperatingExpenses	83,456,857us-gaap_OperatingExpenses	63,541,899us-gaap_OperatingExpenses
Operating income	43,773,928us-gaap_OperatingIncomeLoss	27,775,174us-gaap_OperatingIncomeLoss	11,553,788us-gaap_OperatingIncomeLoss
Interest expense and other finance expenses	(27,593,259)us-gaap_InterestExpense	(15,854,978)us-gaap_InterestExpense	(11,379,857)us-gaap_InterestExpense
Gain on consolidation of joint venture		20,381,849roic_GainOnConsolidationOfJointVenture	2,144,696roic_GainOnConsolidationOfJointVenture
Gain on bargain purchase			3,864,145
Equity in earnings from unconsolidated joint ventures		2,389,937	1,697,980
Gain on sale of real estate	4,868,553
Interest income			11,861us-gaap_InvestmentIncomeInterest
Income from continuing operations	21,049,222	34,691,982	7,892,613
Loss from discontinued operations		(713,529)
Net Income Attributable to Retail Opportunity Investments Partnership, LP	21,049,222us-gaap_ProfitLoss	33,978,453us-gaap_ProfitLoss	7,892,613us-gaap_ProfitLoss
Net income attributable to non-controlling interest	(748,177)	(164,892)
Net Income Attributable to Retail Opportunity Investments Corp.	20,301,045us-gaap_NetIncomeLoss	33,813,561us-gaap_NetIncomeLoss	7,892,613us-gaap_NetIncomeLoss
Net income per share - basic:
Income from continuing operations (in Dollars per share)	$ 0.24	$ 0.51	$ 0.15
Loss from discontinued operations (in Dollars per share)		$ (0.01)
Net earnings per share (in Dollars per share)	$ 0.24us-gaap_EarningsPerShareBasic	$ 0.50us-gaap_EarningsPerShareBasic	$ 0.15us-gaap_EarningsPerShareBasic
Net income per share - diluted:
Income from continuing operations (in Dollars per share)	$ 0.24	$ 0.49	$ 0.15
Loss from discontinued operations (in Dollars per share)		$ (0.01)
Net earnings per share (in Dollars per share)	$ 0.24us-gaap_EarningsPerShareDiluted	$ 0.48us-gaap_EarningsPerShareDiluted	$ 0.15us-gaap_EarningsPerShareDiluted
Dividends per common share (in Dollars per share)	$ 0.64	$ 0.60	$ 0.53
Comprehensive income:
Net income	21,049,222us-gaap_ProfitLoss	33,978,453us-gaap_ProfitLoss	7,892,613us-gaap_ProfitLoss
Unrealized gain (loss) on swap derivative
Unrealized swap derivative gain (loss) arising during the period	(3,131,969)	4,564,248	(7,859,264)
Reclassification adjustment for amortization of interest expense included in net income	3,218,689	4,621,227	3,799,482
Other comprehensive income (loss)	86,720	9,185,475	(4,059,782)
Comprehensive income (loss)	21,135,942	43,163,928	3,832,831
Comprehensive income attributable to non-controlling interests	(748,177)	(164,892)
Comprehensive income attributable to Retail Opportunity Investments Corp.	20,387,765us-gaap_ComprehensiveIncomeNetOfTax	42,999,036us-gaap_ComprehensiveIncomeNetOfTax	3,832,831us-gaap_ComprehensiveIncomeNetOfTax
Retail Opportunity Investments Partnership L.P. [Member]
Revenues
Base rents	119,841,623	86,194,511	59,218,635
Recoveries from tenants	32,945,321	22,497,745	13,483,825
Mortgage interest		623,793	1,106,089
Other income	3,076,567	1,915,982	1,287,138
Total revenues	155,863,511	111,232,031	75,095,687
Operating expenses
Property operating	25,035,765	19,749,972	12,779,758
Property taxes	15,953,210	11,246,967	7,281,213
Depreciation and amortization	58,434,981	40,397,895	29,074,709
General and administrative expenses	11,199,632	10,058,669	12,734,254
Acquisition transaction costs	961,167	1,688,521	1,347,611
Other expenses	504,828	314,833	324,354
Total operating expenses	112,089,583	83,456,857	63,541,899
Operating income	43,773,928	27,775,174	11,553,788
Interest expense and other finance expenses	(27,593,259)	(15,854,978)	(11,379,857)
Gain on consolidation of joint venture		20,381,849	2,144,696
Gain on bargain purchase			3,864,145
Equity in earnings from unconsolidated joint ventures		2,389,937	1,697,980
Gain on sale of real estate	4,868,553
Interest income			11,861
Income from continuing operations	21,049,222	34,691,982	7,892,613
Loss from discontinued operations		(713,529)
Net Income Attributable to Retail Opportunity Investments Partnership, LP	21,049,222	33,978,453	7,892,613
Net income per share - basic:
Income from continuing operations (in Dollars per share)	$ 0.24	$ 0.51	$ 0.15
Loss from discontinued operations (in Dollars per share)		$ (0.01)
Net earnings per share (in Dollars per share)	$ 0.24	$ 0.50	$ 0.15
Net income per share - diluted:
Income from continuing operations (in Dollars per share)	$ 0.24	$ 0.49	$ 0.15
Loss from discontinued operations (in Dollars per share)		$ (0.01)
Net earnings per share (in Dollars per share)	$ 0.24	$ 0.48	$ 0.15
Dividends per common share (in Dollars per share)	$ 0.64	$ 0.60	$ 0.53
Comprehensive income:
Net income	21,049,222	33,978,453	7,892,613
Unrealized gain (loss) on swap derivative
Unrealized swap derivative gain (loss) arising during the period	(3,131,969)	4,564,248	(7,859,264)
Reclassification adjustment for amortization of interest expense included in net income	3,218,689	4,621,227	3,799,482
Other comprehensive income (loss)	86,720	9,185,475	(4,059,782)
Comprehensive income (loss)	$ 21,135,942	$ 43,163,928	$ 3,832,831

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