Accounting Policies [Abstract] Summary of identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) Schedule of Intangible Assets and Liabilities [Table Text Block] Tabular disclosure of the aggregate amount of intangible assets and liabilities. Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of Real Estate Properties [Table] Schedule of Real Estate Properties [Table] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate [Domain] Real Estate [Domain] Office Office Properties [Member] Represents the investment in office properties owned by the entity. Retail Retail Properties [Member] Represents information pertaining to retail properties owned by the entity. Development Properties Development Properties [Member] Represents the development properties owned by the entity. Commercial Commercial Property [Member] Commercial Property [Member] Residential Residential Real Estate [Member] Dual property type, retail portion Dual Property Type, Retail Portion [Member] Dual Property Type, Retail Portion [Member] Dual property type, residential portion Dual Property Type, Residential Portion [Member] Dual Property Type, Residential Portion [Member] Real Estate by Location [Axis] Real Estate by Location [Axis] Represents details pertaining to the locations of real estate properties of the entity. Real Estate by Location [Domain] Real Estate by Location [Domain] Identifies real estate properties of the entity by location. Manhattan Manhattan [Member] Represents information pertaining to properties located in Manhattan. Suburban Suburban [Member] Represents information pertaining to property located in Suburban areas. Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] 919 Third Avenue Third Avenue, 919 [Member] Represents the information pertaining to 919 Third Avenue, a property owned by the entity. 2 Herald Square 2 Herald Square [Member] 2 Herald Square [Member] 131-137 Spring Street Spring Street 131 to 137 [Member] Represents information pertaining to property located at 131-137 Spring Street, owned by the entity. Real estate properties Real Estate Properties [Line Items] Percentage of ownership in SL Green Operating Partnership owned by SL Green Realty Corp (as a percent) Ownership Interest by Parent Ownership Interest by Parent Number of Properties Number of Real Estate Buildings Number of Real Estate Buildings Approximate Square Feet (sqft) Area of Real Estate Property Weighted Average Occupancy (as a percent) Real Estate Weighted Average Occupancy Represents the weighted average occupancy of real estate properties owned, which represents the total leased square feet divided by the total available rentable square feet. Number of unconsolidated joint venture properties Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Number of Properties Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Number of Properties Debt and preferred equity investments including investments held by unconsolidated joint ventures Mortgage Loans on Real Estate, Commercial and Consumer, Net Including Debt Investments, Other Mortgage Loans on Real Estate, Commercial and Consumer, Net Including Debt Investments, Other Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Alliance Building Services Alliance Building Services [Member] Represents the information pertaining to Alliance Building Services, which is a related party of the entity. SL Green SL Green Realty Corp [Member] Represents information pertaining to the SL Green Realty Corp. Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Affiliate Affiliated Entity [Member] Related Party Transactions Related Party Transaction [Line Items] Profit participation received by related party Related Party Transaction, Profit Participation Received by Related Party Represents the amount of profit participation received by related party as per agreements entered into with related party. Payments made for services Related Party Transaction, Expenses from Transactions with Related Party Allocation of salary and other operating costs from related party Related Party Transaction, Operating Expenses Allocated from Related Party Represents the amount of operating expenses allocated from related party. Insurance expense incurred Related Party Transaction, Insurance Expense with Related Party Represents the amount of insurance expense incurred with related party. Notes payable, related parties Notes Payable, Related Parties Interest rate Debt Instrument, Interest Rate, Stated Percentage Derivative Instruments and Hedging Activities Disclosure [Abstract] Financial Instruments: Derivatives and Hedging Derivative Instruments and Hedging Activities Disclosure [Text Block] Discontinued Operations and Disposal Groups [Abstract] Summary Of Properties Sold Disposal Groups, Including Discontinued Operations [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Mortgage Note and Other Loans Payable -- None. No documentation exists for this element. -- Mortgages and Other Loans Payable Mortgage Notes and Other Loans Payable Disclosure [Text Block] Description and amounts of mortgage notes and other loans payable disclosure at the end of the reporting period. This element may be used for the entire disclosure as a single block of text. Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Discontinued Operations, Disposed of by Sale Discontinued Operations, Disposed of by Sale [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Schedule of general information on joint ventures Equity Method Investments [Table Text Block] Schedule of first mortgage notes payable collateralized by the respective joint venture properties and assignment of leases Schedule of Mortgage and Other Loans Payable on Joint Venture Properties [Table Text Block] Tabular disclosure of the information pertaining to mortgage and other loans payable on joint venture properties of the entity. Schedule of combined balance sheets for the unconsolidated joint ventures Equity Method Investments, Summarized Financial Information Balance Sheet [Table Text Block] Disclosure of summarized balance sheet financial information for investments accounted for using the equity method of accounting. Schedule of combined statements of operations for the unconsolidated joint ventures Equity Method Investments, Summarized Financial Information Income Statement [Table Text Block] Disclosure of summarized income statement information for investments accounted for using the equity method of accounting. Commitments and Contingencies Disclosure [Abstract] Schedule of future minimum lease payments under capital leases and noncancellable operating leases Schedule of Future, Minimum Lease Payments for Capital and Operating Leases [Table Text Block] Tabular disclosure of future minimum payments as of the date of the latest balance sheet presented, in aggregate and for each of the five succeeding fiscal years, for capital and operating leases. In case of capital leases the disclosure may include separate deductions from the total for the amount representing executor costs, including any profit thereon, included in the minimum lease payments and for the amount of the imputed interest necessary to reduce the net minimum lease payments to present value. Debt Disclosure [Abstract] Schedule of senior unsecured notes and other related disclosures by scheduled maturity date Schedule of Long-term Debt Instruments [Table Text Block] Schedule of combined aggregate principal maturities of mortgage and other loans payable, 2012 credit facility and senior unsecured notes, including as-of-right extension options Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of consolidated interest expense, excluding capitalized interest Schedule of Interest Expense [Table Text Block] Tabular disclosure of the information pertaining to interest expenses incurred during the period but excluding the interest capitalized. The disclosure may include interest income earned during the period. Investments, Debt and Equity Securities [Abstract] Schedule of debt and preferred equity book balance roll forward Schedule Of Debt And Preferred Equity Book Balance Roll Forward [Table Text Block] Schedule Of Debt And Preferred Equity Book Balance Roll Forward Summary of debt investments Schedule of Mortgage Loans on Real Estate [Table Text Block] Tabular disclosure of investments in mortgage loans on real estate. Schedule of preferred equity investments Investments Classified by Contractual Maturity Date [Table Text Block] Statement of Cash Flows [Abstract] Operating Activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net income to net cash provided by operating activities: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Equity in net income from unconsolidated joint ventures Income (Loss) from Equity Method Investments Distributions of cumulative earnings from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate Equity Method Investment, Realized Gain (Loss) on Disposal Purchase price and other fair value adjustments Purchase Price, Fair Value Adjustment Purchase Price, Fair Value Adjustment Loss (gain) on sale of real estate Gains (Losses) on Sales of Investment Real Estate Depreciable real estate reserves Depreciable Real Estate Reserves, Cash Flow Effect Depreciable Real Estate Reserves, Cash Flow Effect Deferred rents receivable Straight Line Rent Other non-cash adjustments Other Noncash Income (Expense) Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Tenant and other receivables Increase (Decrease) in Accounts Receivable Deferred lease costs Increase (Decrease) in Deferred Leasing Fees Other assets Increase (Decrease) in Other Operating Assets Accounts payable, accrued expenses, other liabilities and security deposits Increase (Decrease) in Accrued Liabilities and Other The change during the period in carrying value of accounts payable, accrued expenses and fair value of hedges, due within one year or operating cycle. Deferred revenue and land leases payable Increase (Decrease) in Deferred Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Investing Activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Acquisitions of real estate properties Payments to Acquire Real Estate Additions to land, buildings and improvements Payments to Acquire Productive Assets Investments in unconsolidated joint ventures Payments to Acquire Equity Method Investments Distributions in excess of cumulative earnings from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution, Return of Capital Net proceeds from disposition of real estate/joint venture interest Proceeds from Real Estate and Real Estate Joint Ventures Other investments Payments for (Proceeds from) Other Investing Activities Origination of debt and preferred equity investments Payments to Acquire Investments Repayments or redemption of debt and preferred equity investments Payments for (Proceeds from) Investments Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Financing Activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from mortgages and other loans payable Proceeds from Issuance of Secured Debt Proceeds from revolving credit facility and senior unsecured notes Proceeds from Issuance of Unsecured Debt Repayments of revolving credit facility and senior unsecured notes Repayments of Unsecured Debt Distributions to noncontrolling interests in other partnerships Distributions to Noncontrolling Interests Other Partnerships The cash outflow for distributions to the entity's partner from a consolidated joint venture. Contributions from common unitholder Proceeds from Partnership Contribution Distributions to common and preferred unitholders Distribution Made to Limited Partner, Cash Distributions Paid Other obligations related to loan participations Proceeds from Participating Mortgage Loan The cash inflow from participating mortgage loans and other mortgage obligations during the reporting period. Deferred loan costs and capitalized lease obligation Amortization of Deferred Loan Origination Fees, Net Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net (decrease) increase in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents, and restricted cash at beginning of year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash at end of period Supplemental Disclosure of Non-Cash Investing and Financing Activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Tenant improvements and capital expenditures payable Capital Expenditures Incurred but Not yet Paid Transfer of assets related to assets held for sale Transfer to Net Assets Held For Sale Value of assets transferred to assets held-for-sale in noncash transactions during the reporting period. Transfer of liabilities related to assets held for sale Transfer to Liabilities Related to Net Assets Held For Sale Value of liabilities transferred to liabilities related to assets held-for-sale in noncash transactions during the reporting period. Removal of fully depreciated commercial real estate properties Removal of Fully Depreciated Real Estate Assets Removal of Fully Depreciated Real Estate Assets Contributions from common unitholder Contributions from Common Unitholder Value of contributions from common unitholder in noncash investing and financing activities. Distributions to common unitholder Distributions From Common Unitholder Distributions From Common Unitholder Deconsolidation of a subsidiary Deconsolidation Real Estate Investments Represents the change in the carrying value of real estate investments resulting from deconsolidation. Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents Total cash, cash equivalents, and restricted cash Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] 115-117 Stevens Avenue Stevens Avenue, 115 to 117 [Member] Represents the information pertaining to 115-117 Stevens Avenue, a property owned by the entity. 635 Madison Avenue Madison Avenue 635 [Member] Madison Avenue 635 [Member] 1-6 International Drive 1-6 International Drive [Member] 1-6 International Drive [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Approximate Square Feet Sales price Disposal Group, Including Discontinued Operation, Consideration Gain (loss) on sale Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Line of Credit Facility [Table] Line of Credit Facility [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Ticonderoga Insurance Company Ticonderoga Insurance Company [Member] Ticonderoga Insurance Company [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] FHLB, advances, amount Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Joint Venture Corporate Joint Venture [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Mortgage Loans on Real Estate, Loan Type [Axis] Mortgage Loans on Real Estate, Loan Type [Axis] Mortgage Loans on Real Estate, Loan Type [Domain] Mortgage Loans on Real Estate, Loan Type [Domain] Mezzanine Loan Due July 2036 Mezzanine Loan Due July 2036 [Member] Mezzanine Loan Due July 2036 [Member] Mezzanine Loans And Preferred Equity Mezzanine Loans And Preferred Equity [Member] Mezzanine Loans And Preferred Equity [Member] Ownership Interest (as a percent) Equity Method Investment, Ownership Percentage Economic Interest (as a percent) Equity Method Investment, Economic Interest Percentage The percentage of economic interest in the investee accounted for under the equity method of accounting. Unaudited Approximate Square Feet (sqft) Acquisition Price Equity Method Investment, Aggregate Cost Purchase price and other fair value adjustments Purchase Price Fair Value Adjustment Gross The impact of fair value adjustments on purchase price and it's impact on net income or loss for the period, gross. Acquisition, development and construction arrangements, carrying value Loans Receivable, Gross, Commercial, Acquisition Tenancy in common interest, percent Leasehold Investment, Tenancy In Common Interest, Ownership Percentage Leasehold Investment, Tenancy In Common Interest, Ownership Percentage Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Investments in Unconsolidated Joint Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Corporate Indebtedness Debt Disclosure [Text Block] Derivative [Table] Derivative [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap Interest Rate Swap [Member] Derivative [Line Items] Derivative [Line Items] Deferred net losses from terminated hedges Accumulated Other Comprehensive Income (Loss), Gain (Loss) on Settlement of Derivatives Represents the amount of gain (loss) incurred from the settlement of derivative instruments included in accumulated other comprehensive income (loss). Amount of Loss Recognized in Other Comprehensive Loss (Effective Portion) Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss) Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net Amount of Gain Recognized into Income (Ineffective Portion) Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness Minimum initial term of noncancellable operating leases (in years) Operating Leases, Minimum Lease Term Represents the initial minimum term of the non cancellable operating leases. Non-cancellable operating leases Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Remaining 2018 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2019 Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years 2023 Operating Leases, Future Minimum Payments, Due in Six Years Operating Leases, Future Minimum Payments, Due in Six Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total minimum lease payments Operating Leases, Future Minimum Payments Due Properties Held for Sale and Property Dispositions Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Partners' Capital Notes [Abstract] Partners' Capital Partners' Capital Notes Disclosure [Text Block] Mortgage Loans on Real Estate Schedule [Table] Mortgage Loans on Real Estate Schedule [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Fixed Rate Investments Fixed Rate [Member] Fixed Rate [Member] Floating Rate Investments Debt Investment with Floating Interest Rate [Member] Represents the debt investment in mortgage loans having a floating interest rate. Mezzanine Loan with an Initial Maturity Date of March 2020 Mezzanine Loan with an Initial Maturity Date of March 2020 [Member] Mezzanine Loan with an Initial Maturity Date of March 2020 [Member] Mezzanine Loan, September 2021 Mezzanine Loan with an Initial Maturity Date of September 2021 [Member] Mezzanine Loan with an Initial Maturity Date of September 2021 [Member] Mezzanine Loan with an Initial Maturity Date of April 2022 Mezzanine Loan with an Initial Maturity Date of April 2022 [Member] Mezzanine Loan with an Initial Maturity Date of April 2022 [Member] Mezzanine Loan with an Initial Maturity of August 2022 Mezzanine Loan With An Initial Maturity Of August 2022 [Member] Mezzanine Loan With An Initial Maturity Of August 2022 Mezzanine Loan, with an Initial Maturity Date of November 2023 Mezzanine Loan, with an Initial Maturity Date of November 2023 [Member] Mezzanine Loan, with an Initial Maturity Date of November 2023 [Member] Mezzanine Loan with an Initial Maturity Date of June 2024 Mezzanine Loan with an Initial Maturity Date of June 2024 [Member] Mezzanine Loan with an Initial Maturity Date of June 2024 [Member] Mezzanine Loan, with an Initial Maturity Date of January 2025 Mezzanine Loan, with an Initial Maturity Date of January 2025 [Member] Mezzanine Loan, with an Initial Maturity Date of January 2025 [Member] Mezzanine Loan with an Initial Maturity Date of November 2026 Mezzanine Loan with an Initial Maturity Date of November 2026 [Member] Mezzanine Loan with an Initial Maturity Date of November 2026 Mezzanine Loan with an Initial Maturity Date of June 2027 Mezzanine Loan with an Initial Maturity Date of June 2027 [Member] Mezzanine Loan with an Initial Maturity Date of June 2027 [Member] Mortgage and Jr Mortgage loan satisfied via foreclosure Mortgage and Jr Mortgage loan satisfied via foreclosure [Member] Mortgage and Jr Mortgage loan satisfied via foreclosure [Member] Mezzanine Loan Repaid In August 2018 Mezzanine Loan Repaid In August 2018 [Member] Mezzanine Loan Repaid In August 2018 [Member] Mortgage Loan Repaid In September 2018 Mortgage Loan Repaid In September 2018 [Member] Mortgage Loan Repaid In September 2018 [Member] Mezzanine Loan, August 2018 Mezzanine Loan with an Initial Maturity Date of August 2018 [Member] Mezzanine Loan with an Initial Maturity Date of August 2018 [Member] Mezzanine Loan, October 2018 Mezzanine Loan with an Initial Maturity Date of October 2018 [Member] Mezzanine Loan with an Initial Maturity Date of October 2018 [Member] Mezzanine Loan, December 2018 Mezzanine Loan with an Initial Maturity Date of December 2018 [Member] Mezzanine Loan with an Initial Maturity Date of December 2018 [Member] Mezzanine Loan, December 2018 Mezzanine Loan with an Initial Maturity Date of December 2018, 2 [Member] Mezzanine Loan with an Initial Maturity Date of December 2018, 2 [Member] Mezzanine Loan, December 2018 Mezzanine Loan with an Initial Maturity Date of December 2018, 3 [Member] Mezzanine Loan with an Initial Maturity Date of December 2018, 3 [Member] Mezzanine Loan, January 2019 Mezzanine Loan with an Initial Maturity Date of January 2019 [Member] Mezzanine Loan with an Initial Maturity Date of January 2019 [Member] Mezzanine Loan with an Initial Maturity of March 2019 Mezzanine Loan with an Initial Maturity of March 2019 [Member] Mezzanine Loan with an Initial Maturity of March 2019 [Member] Mortgage Loan With An Initial Maturity Date Of February 2019 Mortgage Loan With An Initial Maturity Date Of February 2019 [Member] Mortgage Loan With An Initial Maturity Date Of February 2019 [Member] Mezzanine Loan with an Initial Maturity of March 2019, 2 Mezzanine Loan with an Initial Maturity of March 2019, 2 [Member] Mezzanine Loan with an Initial Maturity of March 2019, 2 [Member] Mezzanine Loan with an Initial Maturity Date of April 2019 Mezzanine Loan with an Initial Maturity Date of April 2019 [Member] Mezzanine Loan with an Initial Maturity Date of April 2019 [Member] Mezzanine Loan with an Initial Maturity Date of April 2019 Mezzanine Loan with an Initial Maturity Date of April 2019, 2 [Member] Mezzanine Loan with an Initial Maturity Date of April 2019, 2 [Member] Mezzanine Loan With An Initial Maturity Date Of April 2019, 3 Mezzanine Loan With An Initial Maturity Date Of April 2019, 3 [Member] Mezzanine Loan With An Initial Maturity Date Of April 2019, 3 [Member] Mezzanine Loan With An Initial Maturity Date Of April 2019, 4 Mezzanine Loan With An Initial Maturity Date Of April 2019, 4 [Member] Mezzanine Loan With An Initial Maturity Date Of April 2019, 4 [Member] Mortgage/Jr Mortgage Participate Loan, Maturity Date of August 2019 Mortgage/Jr Mortgage Participate Loan, Maturity Date of August 2019 [Member] Mortgage/Jr Mortgage Participate Loan, Maturity Date of August 2019 [Member] Mortgage/Mezzanine Loan With An Initial Maturity Date Of August 2019 Mortgage/Mezzanine Loan With An Initial Maturity Date Of August 2019 [Member] Mortgage/Mezzanine Loan With An Initial Maturity Date Of August 2019 [Member] Mezzanine Loan With An Initial Maturity Date Of August 2019 Mezzanine Loan With An Initial Maturity Date Of August 2019 [Member] Mezzanine Loan With An Initial Maturity Date Of August 2019 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of September 2019 Mortgage/Mezzanine Loan with an Initial Maturity of September 2019 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of September 2019 [Member] Mezzanine Loan with an Initial Maturity of October 2019 Mezzanine Loan with an Initial Maturity of October 2019 [Member] Mezzanine Loan with an Initial Maturity of October 2019 [Member] Mortgage/Mezzanine Loan with an Initial Maturity Date of December 2019 Mortgage/Mezzanine Loan with an Initial Maturity Date of December 2019 [Member] Mortgage/Mezzanine Loan with an Initial Maturity Date of December 2019 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of January 2020 Mortgage/Mezzanine Loan with an Initial Maturity of January 2020 [Member] [Member] Mortgage/Mezzanine Loan with an Initial Maturity of January 2020 [Member] [Member] Mezzanine Loan with an Initial Maturity of January 2020 Mezzanine Loan with an Initial Maturity of January 2020 [Member] Mezzanine Loan with an Initial Maturity of January 2020 [Member] Mortgage Loan with an Initial Maturity of February 2020 Mortgage Loan with an Initial Maturity of February 2020 [Member] Mortgage Loan with an Initial Maturity of February 2020 [Member] Debt Investments in Mortgage Loans Debt Investments in Mortgage Loans [Member] Represents debt investments in mortgage loans on real estate. Junior Mortgage Participation, Related To Mortgage Loan, February 2019 Junior Mortgage Participation, Related To Mortgage Loan, February 2019 [Member] Junior Mortgage Participation, Related To Mortgage Loan, February 2019 [Member] Preferred Equity Investments in Mortgage Loans Preferred Equity Investments in Mortgage Loans [Member] Represents preferred equity investments in mortgage loans on real estate. Preferred Equity, April 2021 Preferred Equity, April 2021 [Member] Preferred Equity, April 2021 [Member] Junior Mortgage Participation Acquired in September 2014 Junior Mortgage Participation Acquired in September 2014 [Member] Junior Mortgage Participation Acquired in September 2014 [Member] Mortgage and Mezzanine Loan with an Initial Maturity Date of April 2020 Mortgage and Mezzanine Loan with an Initial Maturity Date of April 2020 [Member] Mortgage and Mezzanine Loan with an Initial Maturity Date of April 2020 [Member] Mezzanine Loan with an Initial Maturity of July 2020 Mezzanine Loan with an Initial Maturity of July 2020 [Member] Mezzanine Loan with an Initial Maturity of July 2020 [Member] Mezzanine Loan with an Initial Maturity of November 2020 Mezzanine Loan with an Initial Maturity of November 2020 [Member] Mezzanine Loan with an Initial Maturity of November 2020 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of December 2020 Mortgage/Mezzanine Loan with an Initial Maturity of December 2020 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of December 2020 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of December 2020, 2 Mortgage/Mezzanine Loan with an Initial Maturity of December 2020, 2 [Member] Mortgage/Mezzanine Loan with an Initial Maturity of December 2020, 2 [Member] Jr Mortgage Participation/Mezzanine Loan with an Initial Maturity of July 2021 Jr Mortgage Participation/Mezzanine Loan with an Initial Maturity of July 2021 [Member] Jr Mortgage Participation/Mezzanine Loan with an Initial Maturity of July 2021 [Member] Mortgage/Mezzanine Loan Repaid In February 2018, 2 Mortgage/Mezzanine Loan Repaid In February 2018, 2 [Member] Mortgage/Mezzanine Loan Repaid In February 2018, 2 [Member] Mortgage/Mezzanine Loan repaid in February 2018 Mortgage/Mezzanine Loan repaid in February 2018 [Member] Mortgage/Mezzanine Loan repaid in February 2018 [Member] Mortgage/Mezzanine Loan Sold In May 2018 Mortgage/Mezzanine Loan Sold In May 2018 [Member] Mortgage/Mezzanine Loan Sold In May 2018 [Member] Mezzanine Loan Exchanged For Property In July 2018 Mezzanine Loan Exchanged For Property In July 2018 [Member] Mezzanine Loan Exchanged For Property In July 2018 [Member] Mezzanine Loan Repaid In July 2018 Mezzanine Loan Repaid In July 2018 [Member] Mezzanine Loan Repaid In July 2018 [Member] Mezzanine Loan Repaid In July 2018, 2 Mezzanine Loan Repaid In July 2018, 2 [Member] Mezzanine Loan Repaid In July 2018, 2 [Member] Mortgage/Mezzanine Loan Repaid In August 2018 Mortgage/Mezzanine Loan Repaid In August 2018 [Member] Mortgage/Mezzanine Loan Repaid In August 2018 [Member] Mezzanine Loan Repaid In September 2018 Mezzanine Loan Repaid In September 2018 [Member] Mezzanine Loan Repaid In September 2018 [Member] Mortgage Loans on Real Estate [Line Items] Mortgage Loans on Real Estate [Line Items] Interest rate (as a percent) Mortgage Loans on Real Estate, Interest Rate Payments to acquire loans receivable Payments to Acquire Loans Receivable Debt Investments Held [Abstract] Debt Investments Held [Abstract] Debt Investments Held [Abstract] Future Funding Obligations Loans and Leases Receivable, Funding Obligation Loans and Leases Receivable, Funding Obligation Senior Financing Mortgage Loans on Real Estate, Senior Debt on Investment Amount as of the balance sheet date of debt which holds a position senior to the entity's investment in a mortgage loan on real estate. Carrying Value Loans and Leases Receivable, Gross Carrying Value Mortgage Loans on Real Estate, Commercial and Consumer, Net Loan acquired Receivable with Imputed Interest, Face Amount Discount on loan acquired Receivable with Imputed Interest, Discount Amount participated out Mortgage Loans on Real Estate Loan Value Represents the amount of loan participation on property mortgage. Number of portfolio segments Financing Receivable, Portfolio Segments Number Represents the number of portfolio segments of financing receivables. Financing receivables included in other assets Financing Receivable, Recorded in Other Assets Represents the amount of financing receivables recorded in other assets on the entity's balance sheet. Statement of Financial Position [Abstract] Assets Assets [Abstract] Commercial real estate properties, at cost: Real Estate Investment Property, at Cost [Abstract] Land and land interests Land Building and improvements Investment Building and Building Improvements Building leasehold and improvements Building Leasehold Improvements, Gross Carrying amount at the balance sheet date of long-lived, depreciable asset that is an addition or improvement to assets held under lease arrangement as well as the initial investment in a leasehold interest. Commercial real estate properties, gross Real Estate Investment Property, at Cost Less: accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Total commercial real estate properties, net Real Estate Investment Property, Net Assets held for sale Disposal Group, Including Discontinued Operation, Assets Cash and cash equivalents Restricted cash Tenant and other receivables, net of allowance of $7,138 and $7,237 in 2018 and 2017, respectively Accounts and Notes Receivable, Net Deferred rents receivable, net of allowance of $9,553 and $11,189 in 2018 and 2017, respectively Deferred Rent Receivables, Net Debt and preferred equity investments, net of discounts and deferred origination fees of $16,973 and $25,507 in 2018 and 2017, respectively Investments in unconsolidated joint ventures Equity Method Investments Deferred costs, net of accumulated amortization of $81,131 and $77,176 in 2018 and 2017, respectively Deferred Costs, Leasing, Net Other assets Other Assets Total assets Assets Liabilities Liabilities [Abstract] Mortgages and other loans payable, net Secured and Unsecured Debt Secured and Unsecured Debt Unsecured term loan, net Senior Notes Accrued interest payable Interest Payable Other liabilities Other Liabilities Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Related party payables Due to Related Parties, Noncurrent Deferred revenue Deferred Revenue Deferred land leases payable Deferred Rent Credit Dividends payable Dividends Payable Security deposits Security Deposit Liability Liabilities related to assets held for sale Disposal Group, Including Discontinued Operation, Liabilities Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Preferred units Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount Capital Partners' Capital, Including Portion Attributable to Noncontrolling Interest [Abstract] General partner capital General Partners' Capital Account Limited partner capital Limited Partners' Capital Account Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total ROP partner's capital Partners' Capital Noncontrolling interests in other partnerships Partners' Capital Attributable to Noncontrolling Interest Total capital Partners' Capital, Including Portion Attributable to Noncontrolling Interest Total liabilities and capital Liabilities and Equity Debt and Preferred Equity Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Net income attributable to ROP common unitholder Income (Loss) Attributable to Parent, before Tax Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Change in net unrealized gain on derivative instruments Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent Comprehensive income attributable to ROP common unitholder Comprehensive Income (Loss), Net of Tax, Attributable to Parent Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Partnership Interest Partnership Interest [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series A Preferred Units Series A Preferred Stock [Member] Class of Stock [Line Items] Class of Stock [Line Items] Number of units authorized (in shares) Common Stock Capital Shares Reserved Issuance upon Redemption of Units of Limited Partnership Represents the number of common shares reserved for issuance upon redemption of units of the limited partnership interest. Dividend rate, preferred units (as a percent) Preferred Stock, Dividend Rate, Percentage Liquidation preference of preferred units (in usd per share) Temporary Equity, Liquidation Preference Per Share Number of units issued (in shares) Temporary Equity, Shares Issued Annual dividends on preferred units (in usd per share) Preferred Stock, Dividends, Per Share, Cash Paid Number of company common stock issued on conversion of Series B preferred units Preferred Stock, Convertible Conversion Ratio Preferred Stock, Convertible Conversion Ratio Fair value of embedded derivative Embedded Derivative, Fair Value of Embedded Derivative Liability Segment Reporting [Abstract] Segment Information Segment Reporting Disclosure [Text Block] Statement [Table] Statement [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity Variable Interest Entity, Primary Beneficiary [Member] Statement Statement [Line Items] Tenant and other receivables, net of allowance of $7,138 and $7,237 in 2018 and 2017, respectively Allowance for Doubtful Accounts, Premiums and Other Receivables Deferred rents receivable, net of allowance of $9,553 and $11,189 in 2018 and 2017, respectively Allowance for Deferred Rents Receivable The valuation allowances attributable to, for instance, credit risk associated with a lessee as of the balance sheet date to reduce the gross amount of deferred rents receivable, which would be presented in parentheses on the face of the balance sheet. Debt and preferred equity investments, net of discounts and deferred origination fees of $16,973 and $25,507 in 2018 and 2017, respectively Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums Deferred costs, net of accumulated amortization of $81,131 and $77,176 in 2018 and 2017, respectively Accumulated Amortization of Other Deferred Costs Accumulated depreciation Real estate debt, net Secured Debt Schedule of commercial office properties Schedule of Real Estate Properties [Table Text Block] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Weighted Average Weighted Average [Member] Interest rate (as a percent) Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate Fixed rate debt Secured Debt, Bearing Fixed Interest, Amount The portion of the carrying amount of long-term secured loans outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate. Interest rate (as a percent) Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate Floating rate debt Secured Debt, Bearing Variable Interest, Amount The portion of the carrying amount of long-term secured loans outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time. Total joint venture mortgages and other loans payable Secured Debt and Other Loans, Payable Represents the carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations and other loans payable. Deferred financing costs, net Debt Issuance Costs, Net Total joint venture mortgages and other loans payable, net Secured Debt and Other Loans, Payable, Net Secured Debt and Other Loans, Payable, Net Investment [Axis] Investment [Axis] Investment [Domain] Investment [Domain] Movement in Mortgage Loans on Real Estate [Roll Forward] Movement in Mortgage Loans on Real Estate [Roll Forward] Balance at beginning of period Mortgage Loans on Real Estate Originations/Accretion Mortgage Loans on Real Estate, New Mortgage Loans Redemptions/Sales/Syndications/Amortization Mortgage Loans on Real Estate, Amortization of Premium Balance at end of period Schedule of effect of derivative financial instruments on consolidated statements of income Derivative Instruments, Gain (Loss) [Table Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Document and Entity Information -- None. No documentation exists for this element. -- Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Significant Accounting Policies Significant Accounting Policies [Text Block] Related Party Transactions Related Party Transactions Disclosure [Text Block] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Annualized cash rent Annualized Rent [Member] Annualized rent, when it serves as a benchmark in a concentration of risk calculation. Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Customer concentration Customer Concentration Risk [Member] 1185 Avenue of the Americas Avenue of the Americas, 1185 [Member] Represents the information pertaining to 1185 Avenue of the Americas, a property owned by the entity. 625 Madison Avenue Madison Avenue, 625 [Member] Represents the information pertaining to 625 Madison Avenue, a property owned by the entity. 750 Third Avenue Third Avenue, 750 [Member] Represents the information pertaining to 750 Third Avenue, a property owned by the entity. 810 Seventh Avenue Seventh Avenue, 810 [Member] Represents the information pertaining to 810 Seventh Avenue, a property owned by the entity. 555 W. 57th Street W 57 Street 555 [Member] Represents the information pertaining to 555 W. 57th Street, a property owned by the entity. 125 Park Avenue Park Avenue, 125 [Member] Represents the information pertaining to 125 Park Avenue, a property owned by the entity. 1350 Avenue of the Americas Avenue of the Americas 1350 [Member] Represents information pertaining to 1350 Avenue of the Americas, a property owned by the entity. 711 Third Avenue Third Avenue, 711 [Member] Represents the information pertaining to 711 Third Avenue, a property owned by the entity. Concentrations of Credit Risk Concentration Risk [Line Items] Maximum percentage of annualized cash rent for any one tenant not individually disclosed Concentration Risk Percentage Threshold Represents the maximum percentage of concentration risk that is not individually disclosed. Percentage of concentration Concentration Risk, Percentage Statement of Partners' Capital [Abstract] Partner Capital Components [Axis] Partner Capital Components [Axis] Partner Capital Components [Domain] Partner Capital Components [Domain] General Partner's Capital Class A Common Units General Partner [Member] Limited Partner's Capital Limited Partner [Member] Noncontrolling Interests In Other Partnerships Noncontrolling Interest [Member] Accumulated Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] Class A Common Units Common Class A [Member] Increase (Decrease) in Partners' Capital Increase (Decrease) in Partners' Capital [Roll Forward] Beginning Balance Contributions Partners' Capital Account, Contributions Distributions Partners' Capital Account, Distributions Deconsolidation of partially owned entity Noncontrolling Interest, Decrease from Deconsolidation Net income Profit Loss, Less Preferred Distributions The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest, less preferred distributions during the period. Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Ending Balance Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] 315 West 33rd Street 315 West 33rd Street [Member] 315 West 33rd Street [Member] 115 Spring Street Spring Street 115 [Member] Spring Street 115 [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Uncommitted Master Repurchase Agreements Uncommitted Master Repurchase Agreements [Member] Uncommitted Master Repurchase Agreements [Member] Uncommitted Master Repurchase Agreement 2017 Uncommitted Master Repurchase Agreement 2017 [Member] Uncommitted Master Repurchase Agreement 2017 Uncommitted Master Repurchase Agreement 2016 Uncommitted Master Repurchase Agreement 2016 [Member] Uncommitted Master Repurchase Agreement 2016 [Member] Minimum Minimum [Member] Maximum Maximum [Member] Mortgage note and other loan payable Debt Instrument [Line Items] Total mortgages and other loans payable Secured Debt, Gross Secured Debt, Gross Deferred financing costs, net of amortization Secured Debt, Deferred Finance Costs, Net Secured Debt, Deferred Finance Costs, Net Total mortgages and other loans payable, net Debt and preferred equity investments Collateral Already Posted, Aggregate Fair Value Number of instruments Debt Instrument, Number of Instruments Debt Instrument, Number of Instruments Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Initial term Debt Instrument, Term Number of extension options Debt Instrument, Number of Extension Options Debt Instrument, Number of Extension Options Period of extension option Debt Instrument, Period of Extension Option Debt Instrument, Period of Extension Option Revolving credit facility, net Long-term Line of Credit Credit facility, interest rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Basis point fee (as a percent) Line of Credit Facility, Basis Point Fee Line of Credit Facility, Basis Point Fee Threshold amount for basis point fee to be applicable (less than) Line of Credit Facility, Threshold Amount for Basis Point Fee Line of Credit Facility, Threshold Amount for Basis Point Fee Preferred Units Stockholders' Equity Note Disclosure [Text Block] Schedule of the first mortgage note and other loans payable collateralized by the property, assignment of leases and investment Schedule of Mortgage Note and Other Loan Payable Collateralized by Property and Assignment of Leases [Table Text Block] Tabular disclosure of mortgage note other loan payable collateralized by the property and assignment of leases. Business Combinations [Abstract] Property Acquisitions Business Combination Disclosure [Text Block] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving credit facility Revolving Credit Facility [Member] Term Loan B, Maturity November 21, 2024 Term Loan B, Maturity November 21, 2024 [Member] Term Loan B [Member] Revolving Credit Facility, Maturity March 31, 2022 Revolving Credit Facility, Maturity March 31, 2022 [Member] Revolving Credit Facility, Maturity March 31, 2022 [Member] Term Loan A, Maturity March 31, 2023 Term Loan A, Maturity March 31, 2023 [Member] Term Loan A [Member] Term loan Term Loan [Member] Represents the term loan of the reporting entity. 4.50% Senior Unsecured Bonds Due December 2022 4.50 Percent Senior Unsecured Bonds Due December 2022 [Member] 4.50 Percent Senior Unsecured Bonds Due December 2022 [Member] Credit Facility 2012 Credit Facility 2012 [Member] Represents information pertaining to 2012 Credit Facility. 7.75% senior unsecured notes maturing on March 15, 2020 Senior Unsecured Notes Due March 15, 2020 [Member] Represents senior unsecured notes maturing on March 15, 2020. 4.50% senior unsecured notes maturing on December 01, 2022 Senior Unsecured Notes Due December 1, 2022 [Member] Represents senior unsecured notes bearing an interest rate of 4.50 percent maturing on December 1, 2022. 4.27% senior unsecured notes maturing December 17, 2025 Senior Unsecured Note Due December 17, 2025 [Member] Senior Unsecured Note Due December 17, 2025 [Member] Mortgage and Other Loans Payable Mortgage and Other Loans Payable [Member] Represents mortgage and other loans payable of the entity. Senior Notes Senior Notes [Member] 3.25 Percent Senior Unsecured Notes Due October 2022 3.25 Percent Senior Unsecured Notes Due October 2022 [Member] 3.25 Percent Senior Unsecured Notes Due October 2022 Senior Notes due 2021 Senior Notes Due 2021 [Member] Senior Notes Due 2021 [Member] Senior Unsecured Notes, Due August 15, 2018 Senior Unsecured Notes, Due August 15, 2018 [Member] Represents senior unsecured notes bearing an interest rate of 5 percent maturing on August 15, 2018. Line of Credit Line of Credit [Member] Senior Unsecured Bonds Senior Unsecured Bonds [Member] Senior Unsecured Bonds Senior Unsecured Notes Senior Unsecured Notes [Member] Senior Unsecured Notes [Member] Corporate Indebtedness Number of extensions Line Of Credit Facility, Number Of Extensions Line Of Credit Facility, Number Of Extensions Term of extension Line Of Credit Facility, Term Of Extension Line Of Credit Facility, Term Of Extension Maximum borrowing capacity, optional expansion Line of Credit Facility, Optional Expansion, Maximum Borrowing Capacity The expanded maximum borrowing capacity available, which is subject to agreement with the entity. Interest rate added to base rate (as a percent) Letters of credit Letters of Credit Outstanding, Amount Ability to borrow under line of credit facility Line of Credit Facility, Remaining Borrowing Capacity Carrying value Long-term Debt Face amount Debt Instrument, Face Amount Redemption price, percentage Debt Instrument, Redemption Price, Percentage Debt disclosures by scheduled maturity date Debt Instrument, Information by Scheduled Maturity Date of Debt [Abstract] -- None. No documentation exists for this element. -- Unpaid Principal Balance Long-term Debt, Gross Accreted Balance Coupon Rate (as a percent) Initial Term (in Years) Total Senior Notes, Net of Deferred Finance Costs Senior Notes, Net of Deferred Finance Costs Scheduled Amortization Future Amortization of Debt [Abstract] -- None. No documentation exists for this element. -- Remaining 2018 Future Amortization of Debt, Remainder of Fiscal Year Future Amortization of Debt, Remainder of Fiscal Year 2019 Future Amortization of Debt, Second Full Fiscal Year The amount of amortization of debt expected to be recognized during the second full fiscal year following the date of the most recent balance sheet. 2020 Future Amortization of Debt, Third Full Fiscal Year The amount of amortization of debt expected to be recognized during the third full fiscal year following the date of the most recent balance sheet. 2021 Future Amortization of Debt Fourth Full Fiscal Year The amount of amortization of debt expected to be recognized during the fourth full fiscal year following the date of the most recent balance sheet. 2022 Future Amortization of Debt Fifth Full Fiscal Year The amount of amortization of debt expected to be recognized during the fifth full fiscal year following the date of the most recent balance sheet. Thereafter Future Amortization of Debt after Fifth Full Fiscal Year The amount of amortization of debt expected to be recognized after the fifth full fiscal year following the date of the most recent balance sheet. Total amortization of debt Future Amortization of Debt The total expected future amortization of debt. Principal Repayments Maturities of Long-term Debt [Abstract] Remaining 2018 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2019 Long-term Debt, Maturities, Repayments of Principal in Year Two 2020 Long-term Debt, Maturities, Repayments of Principal in Year Three 2021 Long-term Debt, Maturities, Repayments of Principal in Year Four 2022 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total principal repayments Long Term Debt, Maturities, Repayments of Principal Total amount of long-term debt maturing in future periods. Scheduled amortization and principal repayments Amortization and Maturities of Long-term Debt [Abstract] -- None. No documentation exists for this element. -- Remaining 2018 Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 2019 Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal Second Full Fiscal Year The aggregate amount of amortization of debt expected to be recognized and long-term debt maturing within the second full fiscal year following the date of the latest balance sheet presented in the financial statements. 2020 Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal Third Full Fiscal Year The aggregate amount of amortization of debt expected to be recognized and long-term debt maturing within the third full fiscal year following the date of the latest balance sheet presented in the financial statements. 2021 Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal Fourth Full Fiscal Year The aggregate amount of amortization of debt expected to be recognized and long-term debt maturing within the fourth full fiscal year following the date of the latest balance sheet presented in the financial statements. 2022 Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal Fifth Full Fiscal Year The aggregate amount of amortization of debt expected to be recognized and long-term debt maturing within the fifth full fiscal year following the date of the latest balance sheet presented in the financial statements. Thereafter Future Amortization of Debt and Long Term Debt, Maturities, Repayments of Principal after Fifth Full Fiscal Year The aggregate amount of amortization of debt expected to be recognized and long-term debt maturing after the fifth full fiscal year following the date of the latest balance sheet presented in the financial statements. Total amortization of debt and principal repayments Interest expense Interest Income (Expense), Net [Abstract] Interest expense Interest Expense Interest capitalized Interest Costs Capitalized Interest income Interest Income, Operating Interest expense, net Interest Income (Expense), Net Principles of Consolidation Consolidation, Policy [Policy Text Block] Investment in Commercial Real Estate Properties Investment in Real Estate [Policy Text Block] Disclosure of accounting policy for investments in real estate properties. Investments in Unconsolidated Joint Ventures Equity Method Investments [Policy Text Block] Reserve for Possible Credit Losses Financing Receivable, Allowance for Credit Losses, Policy or Methodology Change [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Shares Contributed by Parent Company Treasury Stock, Policy [Policy Text Block] Treasury Stock, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Concentrations of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Reclassification Reclassification, Policy [Policy Text Block] Accounting Standards Updates New Accounting Pronouncements, Policy [Policy Text Block] Fair Value Measurements Fair Value of Financial Instruments, Policy [Policy Text Block] Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Income Statement [Abstract] Related party expenses included in operating expenses Related Party Costs Mezzanine Loan Mezzanine Loan [Member] Mezzanine Loan [Member] Ownership Interest Gross Asset Valuation Revenues Revenues [Abstract] Rental revenue, net Operating Leases, Income Statement, Minimum Lease Revenue Escalation and reimbursement Tenant Reimbursements Investment income Investment Income, Interest and Dividend Other income Other Operating Income (Expense), Net Total revenues Revenues Expenses Costs and Expenses [Abstract] Operating expenses, including related party expenses of $6,021 and $18,178 in 2018, and $6,922 and $20,099 in 2017, respectively. Operating Costs and Expenses Real estate taxes Real Estate Tax Expense Ground rent Direct Costs of Leased and Rented Property or Equipment Interest expense, net of interest income Amortization of deferred financing costs Amortization of Debt Issuance Costs Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Transaction related costs Transaction Related Costs This Element represents the transaction related costs during the period. Marketing, general and administrative Selling, General and Administrative Expense Total expenses Total Costs and Expenses Including Nonoperating Income (Expense) This element represents the total of the costs related to real estate revenues, including management, leasing, and development services and income (expense) from ancillary business-related activities. Equity in net (loss) income from unconsolidated joint ventures (Loss) gain on sale of real estate Depreciable real estate reserves Depreciable Real Estate Reserves, Effect on Earnings Depreciable Real Estate Reserves, Effect on Earnings Equity in net gain on sale of interest in unconsolidated joint venture/real estate Net income Net (income) loss attributable to noncontrolling interests in other partnerships Income (Loss) Attributable to Noncontrolling Interest, before Tax Preferred units distributions Noncontrolling Interest in Net Income (Loss) Preferred Unit Holders, Redeemable Net income attributable to ROP common unitholder Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Business Segments [Axis] Segments [Axis] Segment [Domain] Segments [Domain] Real Estate Segment Real Estate Segment [Member] Represents the information pertaining to the reportable segment of the entity, Real Estate Segment. Debt and Preferred Equity Segment Structured Finance Segment [Member] Represents the information pertaining to the reportable segment of the entity, Structured Finance Segment. Segment information Segment Reporting Information [Line Items] Number of reportable segments Number of Reportable Segments Total revenues Net income Income (Loss) from Continuing Operations before Realized Gain (Loss) on Disposal of Equity Method Investment This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses and taxes from ongoing operations before realized gains (losses) on disposals of equity method investments, extraordinary items, and noncontrolling interest. Total assets Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Fair Value of Financial Instruments Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Debt and preferred equity investments, net Mortgage Loans On Real Estate Commercial And Consumer And Equity Method Investments Net The balance represents the amount of loans that are secured by real estate mortgages, offset by any reserve to cover probable credit losses on the loan portfolio and deduction of deferred fees, unamortized costs, premiums and discounts from the face amounts. Included in this account is investment in unconsolidated joint venture which reflects the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. Fixed rate debt Long-term Debt, Percentage Bearing Fixed Interest, Amount Variable rate debt Long-term Debt, Percentage Bearing Variable Interest, Amount Total Long-term Debt, Fair Value Estimated fair value of debt and preferred equity investments, low end of range Mortgage Loans on Real Estate, Fair Value, Low End of Range Represents the low end of the range of estimated fair value for investments in mortgage loans on real estate. Estimated fair value of debt and preferred equity investments, high end of range Mortgage Loans on Real Estate Fair Value, High End of Range Represents the high end of the range of estimated fair value for investments in mortgage loans on real estate. Schedule of Property, Plant and Equipment and Finite Lived Intangible Assets and Liabilities, by Major Class [Table] Schedule of Property, Plant and Equipment and Finite Lived Intangible Assets and Liabilities, by Major Class [Table] Table of long-lived, physical assets and finite lived intangible assets and liabilities that are used in the normal conduct of business to produce goods and services and which are not intended for resale. Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Building Building [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Above-market leases Above Market Leases [Member] Below-market leases Leases, Below Market [Member] Leases, Below Market [Member] In-place leases In Place Leases [Member] Represents information pertaining to in-place leases. Investment in Commercial Real Estate Properties Property, Plant and Equipment [Line Items] Estimated useful life (years) Property, Plant and Equipment, Useful Life Estimated useful life of intangible assets (years) Finite-Lived Intangible Asset, Useful Life Increase in rental revenue from amortization of acquired leases Rental Revenue Increase (Decrease) Acquired Lease Amortization Represents the increase (decrease) in rental revenue during the period resulting from the net amortization of acquired above-market and below-market leases. Loan reserves Provision for Loan and Lease Losses Increase in total assets Increase in total liabilities Identified intangible assets (included in other assets): Finite-Lived Intangible Assets, Net [Abstract] Gross amount Finite-Lived Intangible Assets, Gross Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Finite-Lived Intangible Assets, Net Identified intangible liabilities (included in deferred revenue): Finite Lived Intangible Liabilities [Abstract] -- None. No documentation exists for this element. -- Gross amount Finite Lived Intangible Liabilities, Gross Represents the gross carrying amounts before accumulated amortization as of the balance sheet date of all intangible liabilities having statutory or estimated useful lives. Accumulated amortization Finite Lived Intangible Liabilities, Accumulated Amortization Represents the accumulated amount of amortization of a major finite-lived intangible liability class. Net Finite Lived Intangible Liabilities, Net Represents the sum of gross carrying value of a major finite-lived intangible liability class, less accumulated amortization. Net Intangible Assets Transferred to Assets Held for Sale Net Intangible Assets Transferred to Assets Held for Sale Net Intangible Assets Transferred to Assets Held for Sale Net Intangible Liabilities Transferred to Liabilities Related to Assets Held for Sale Net Intangible Liabilities Transferred to Liabilities Related to Assets Held for Sale Net Intangible Liabilities Transferred to Liabilities Related to Assets Held for Sale Assets Equity Method Investment, Summarized Financial Information, Assets [Abstract] Commercial real estate property, net Total assets Equity Method Investment, Summarized Financial Information, Assets Liabilities and members' equity Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract] Mortgages and other loans payable, net Members' equity Equity Method Investment Summarized Financial Information, Equity Total liabilities and members' equity Equity Method Investment, Summarized Financial Information, Liabilities and Equity Company's investments in unconsolidated joint ventures Combined statements of income for the unconsolidated joint ventures Equity Method Investment, Summarized Financial Information, Income Statement [Abstract] Total revenues Equity Method Investment, Summarized Financial Information, Revenue Operating expenses Costs and Expenses Ground rent Interest expense, net of interest income Interest Expense, Net Amount of interest expense paid, net of interest income earned by the entity, during the period. Net income Equity Method Investment, Summarized Financial Information, Net Income (Loss) Company's equity in net income from unconsolidated joint ventures Schedule of selected results of operations and selected asset information Schedule of Segment Reporting Information, by Segment [Table Text Block]