Consolidated Balance Sheets (September 30, 2012 unaudited) Consolidated Balance Sheets (September 30, 2012 unaudited) [Abstract] ASSETS ASSETS [Abstract] Real Estate Investments: Real Estate Investments: [Abstract] Land Building and improvements Less: accumulated depreciation Mortgage note receivable Investment in and advances to unconsolidated joint ventures Real Estate Investments, net Cash and cash equivalents Restricted cash Tenant and other receivables Deposits Acquired lease intangible asset, net of accumulated amortization Prepaid expenses Deferred charges, net of accumulated amortization Other Total assets LIABILITIES AND EQUITY LIABILITIES AND EQUITY [Abstract] Liabilities: Liabilities: [Abstract] Term loan Mortgage notes payable Acquired lease intangibles liability, net of accumulated amortization Accounts payable and accrued expenses Tenants' security deposits Other liabilities Total liabilities Equity: Equity: [Abstract] Preferred stock, $.0001 par value 50,000,000 shares authorized; none issued and outstanding Common stock, $.0001 par value 500,000,000 shares authorized; and 52,518,066 and 49,375,738 shares issued and outstanding at September 30, 2012 and December 31, 2011 Additional paid-in-capital Accumulated deficit Accumulated other comprehensive loss Total Retail Opportunity Investments Corp. stockholders' equity Noncontrolling interests Total equity Total liabilities and equity Preferred stock par value (in Dollars per share) Preferred stock, shares authorized (in Shares) Preferred stock, shares issued (in Shares) Preferred stock, shares outstanding (in Shares) Common stock, par value (in Dollars per share) Common stock, shares authorized (in Shares) Common stock, shares issued (in Shares) Common stock, shares outstanding (in Shares) Consolidated Statements Of Operations And Comprehensive Income (unaudited) Consolidated Statements Of Operations And Comprehensive Income (unaudited) [Abstract] Revenues Revenues [Abstract] This element represents the minimum amount of rents earned during the period from lessees based on the terms of contractual arrangements. Base rents Recoveries from tenants Mortgage interest Total revenues Operating expenses Operating expenses [Abstract] Property operating Property taxes Depreciation and amortization General & Administrative Expenses Acquisition transaction costs Total operating expenses Operating income Non-operating income (expenses) Non-operating income (expenses) [Abstract] Interest expense and other finance expenses Gain on the consolidation of a joint venture. Gain on consolidation of JV Gain on bargain purchase Equity in earnings from unconsolidated joint ventures Interest Income Net Income Attributable to Retail Opportunity Investments Corp. Basic and diluted per share: (in Dollars per share) Dividends per common share (in Dollars per share) Comprehensive (loss) income: Comprehensive (loss) income: [Abstract] Other comprehensive loss Other comprehensive loss [Abstract] Unrealized loss on swap derivative Total other comprehensive loss Total Comprehensive (loss) income Consolidated Statements of Equity (unaudited) Consolidated Statements of Equity (unaudited) [Abstract] Equity Component [Domain] Balance Balance Balance (in Shares) Balance (in Shares) Compensation expense related to options granted Compensation expense related to restricted stock grants Shares issued under the 2009 Plan Shares issued under the 2009 Plan (in Shares) Proceeds from the sale of stock Proceeds from the sale of stock (in Shares) Forfeited Shares (in Shares) Forfeited Shares Registration expenditures Dividends ($.39 per share) Comprehensive income (loss) Comprehensive income (loss) [Abstract] Net Income Attributable to Retail Opportunity Investments Corp. Other Comprehensive Loss Dividends per share (in Dollars per share) Consolidated Statements Of Cash Flows (unaudited) Consolidated Statements Of Cash Flows (unaudited) [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES CASH FLOWS FROM OPERATING ACTIVITIES [Abstract] Net income Adjustments to reconcile net income to cash provided by operating activities: Adjustments to reconcile net income to cash provided by operating activities: [Abstract] Depreciation and amortization Amortization of deferred financing costs Gain on consolidation of JV Gain on bargain purchase Straight-line rent adjustment Amortization of above and below market rent This represents the amortization of restricted stock over the vesting period of the grants Amortization relating to stock based compensation Provisions for tenant credit losses Equity earned in earnings from unconsolidated joint ventures Distribution of cumulative earnings from unconsolidated joint ventures Change in operating assets and liabilities Change in operating assets and liabilities [Abstract] Mortgage escrows Tenant receivables Prepaid expenses Accounts payable and accrued expenses Other asset and liabilities, net Net cash provided by operating activities CASH FLOWS FROM INVESTING ACTIVITIES CASH FLOWS FROM INVESTING ACTIVITIES [Abstract] Investments in real estate Investments in mortgage notes receivables Investments in unconsolidated joint ventures Proceeds from sale of unconsolidated joint ventures Return of capital from unconsolidated joint ventures Proceeds from the sale of land Improvements to properties and deferred charges Deposits on real estate acquisitions Construction escrows and other Net cash used in investing activities CASH FLOWS FROM FINANCING ACTIVITIES CASH FLOWS FROM FINANCING ACTIVITIES [Abstract] Principal repayment on mortgages Proceeds from the draw on term loan/ revolving credit facility Proceeds from the sale of stock Deferred financing and other costs Registration expenditures Dividends paid to common shareholders Net cash provided by financing activities Net decrease in cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Note 1 - Organization, Basis of Presentation and Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Note 2 - Real Estate Investments Real Estate Investment Financial Statements, Disclosure [Table Text Block] Note 3 - Mortgage Notes Payable and Credit Facilities Debt Disclosure [Text Block] Note 4 - Preferred Stock Preferred Stock [Text Block] Note 5 - Common Stock and Warrants Stockholders' Equity Note Disclosure [Text Block] Note 6 - Stock Compensation and Other Benefit Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Note 7 - Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Note 8 - Derivative and Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Note 9 - Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Note 10 - Related Party Transactions Related Party Transactions Disclosure [Text Block] Note 11 - Corporate Office Relocation Disclosure regarding corporate office relocation. Corporate Office Relocation [Text Block] Note 12 - Subsequent Events Subsequent Events [Text Block] Schedule of Earnings Per Share Reconciliation [Table Text Block] Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Schedule of Purchase Price Allocation [Table Text Block] Business Acquisition, Pro Forma Information [Table Text Block] Schedule of Condensed Income Statement [Table Text Block] Schedule of Equity Method Investments [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Interest Rate Derivatives [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block] Reconciliation Between Basic and Diluted EPS Reconciliation Between Basic and Diluted EPS [Abstract] Award Type [Domain] Numerator: Numerator: [Abstract] Net Income attributable to Retail Opportunity Investments Corp. (in Dollars) Less, earnings allocated to unvested shares (in Dollars) Net income available for common shareholders, basic and diluted (in Dollars) Denominator: Denominator: [Abstract] Denominator for basic EPS – weighted average common shares Warrants Share Based Payment Awards Denominator for diluted EPS – weighted average common equivalent shares Supplemental Consolidated Statements of Cash Flow Information Supplemental Consolidated Statements of Cash Flow Information [Abstract] Supplemental disclosure of cash activities: Supplemental disclosure of cash activities: [Abstract] Cash paid for Federal and New York state income taxes