Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Our interim consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and, therefore, do not necessarily include all information and footnotes necessary for a fair statement of our consolidated financial position, results of operations, and cash flows in accordance with generally accepted accounting principles in the United States, or GAAP.
Basis of Consolidation	Basis of Consolidation Our consolidated financial statements reflect all of our accounts, including those of our controlled subsidiaries. The portions of equity in consolidated subsidiaries that are not attributable, directly or indirectly, to us are presented as noncontrolling interests. All significant intercompany accounts and transactions have been eliminated.
Variable Interest Entity	When we obtain an economic interest in an entity, we evaluate the entity to determine if it should be deemed a variable interest entity, or VIE, and, if so, whether we are the primary beneficiary and are therefore required to consolidate the entity. We apply accounting guidance for consolidation of VIEs to certain entities in which the equity investors do not have the characteristics of a controlling financial interest or do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties. Fixed price purchase and renewal options within a lease, as well as certain decision-making rights within a loan or joint-venture agreement, can cause us to consider an entity a VIE. Limited partnerships and other similar entities that operate as a partnership will be considered VIEs unless the limited partners hold substantive kick-out rights or participation rights. Significant judgment is required to determine whether a VIE should be consolidated. We review the contractual arrangements provided for in the partnership agreement or other related contracts to determine whether the entity is considered a VIE and to establish whether we have any variable interests in the VIE. We then compare our variable interests, if any, to those of the other variable interest holders to determine which party is the primary beneficiary of the VIE based on whether the entity (i) has the power to direct the activities that most significantly impact the economic performance of the VIE and (ii) has the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. The liabilities of these VIEs are non-recourse to us and can only be satisfied from each VIE’s respective assets.
Recent Accounting Pronouncements	In May 2014, the Financial Accounting Standards Board, or FASB, issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods or services. ASU 2014-09 does not apply to our lease revenues, which constitute a majority of our revenues, but will primarily apply to revenues generated from our operating properties. We adopted this guidance for our interim and annual periods beginning January 1, 2018 using the modified retrospective transition method applied to any contracts not completed as of that date. There were no changes to the prior period presentations of revenue. Results of operations for reporting periods beginning January 1, 2018 are presented under Topic 606. The adoption of Topic 606 did not have a material impact on our consolidated financial statements. Revenue is recognized when, or as, control of promised goods or services is transferred to customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. At contract inception, we assess the services promised in our contracts with customers and identify a performance obligation for each promise to transfer to the customer a good or service (or bundle of goods or services) that is distinct. To identify the performance obligations, we consider all of the services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. In January 2016, the FASB issued ASU 2016-01, Financial Instruments — Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 requires all equity investments (other than those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value, with changes in the fair value recognized through net income. We adopted this guidance for our interim and annual periods beginning January 1, 2018. The adoption of ASU 2016-01 did not have a material impact on our consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 intends to reduce diversity in practice for certain cash flow classifications, including, but not limited to (i) debt prepayment or debt extinguishment costs, (ii) contingent consideration payments made after a business combination, (iii) proceeds from the settlement of insurance claims, and (iv) distributions received from equity method investees. We retrospectively adopted this guidance for our interim and annual periods beginning January 1, 2018. The adoption of ASU 2016-15 did not have a material impact on our consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. ASU 2016-18 intends to reduce diversity in practice for the classification and presentation of changes in restricted cash on the statement of cash flows. ASU 2016-18 requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. We retrospectively adopted this guidance for our interim and annual periods beginning January 1, 2018. See Restricted Cash above for additional information. In February 2017, the FASB issued ASU 2017-05, Other Income — Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. ASU 2017-05 clarifies the scope and application of Accounting Standards Codification, or ASC, 610-20 on the sale or transfer of nonfinancial assets and in substance nonfinancial assets to non-customers, including partial sales. Nonfinancial assets within the scope of this Subtopic include the sale of land, buildings and intangible assets. ASU 2017-05 further clarifies that a financial asset is within the scope of Subtopic 610-20 if it meets the definition of an in substance nonfinancial asset. The amendments define the term “in substance nonfinancial asset,” in part, as a financial asset promised to a counterparty in a contract if substantially all of the fair value of the assets (recognized and unrecognized) that are promised to the counterparty in the contract is concentrated in nonfinancial assets. This amendment also clarifies that nonfinancial assets within the scope of Subtopic 610-20 may include nonfinancial assets transferred within a legal entity to a counterparty. For example, a parent company may transfer control of nonfinancial assets by transferring ownership interests in a consolidated subsidiary. We adopted this guidance for our interim and annual periods beginning January 1, 2018 and applied the modified retrospective transition method (applicable to any contracts not completed as of that date). The adoption of ASU 2017-05 did not have a material impact on our consolidated financial statements. Pronouncements to be Adopted after March 31, 2018 In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). ASU 2016-02 outlines a new model for accounting by lessees, whereby their rights and obligations under substantially all leases, existing and new, would be capitalized and recorded on the balance sheet. For lessors, however, the accounting remains largely unchanged from the current model, with the distinction between operating and financing leases retained, but updated to align with certain changes to the lessee model and the new revenue recognition standard. The new standard also replaces existing sale-leaseback guidance with a new model applicable to both lessees and lessors. Additionally, the new standard requires extensive quantitative and qualitative disclosures. Early application will be permitted for all entities. The new standard must be adopted using the modified retrospective transition method and provides for certain practical expedients. Transition will require application of the new model at the beginning of the earliest comparative period presented. We will adopt this guidance for our interim and annual periods beginning January 1, 2019. The ASU is expected to impact our consolidated financial statements as we have certain land lease arrangements for which we are the lessee. We are evaluating the impact of the new standard and have not yet determined if it will have a material impact on our business or our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses. ASU 2016-13 introduces a new model for estimating credit losses based on current expected credit losses for certain types of financial instruments, including loans receivable, held-to-maturity debt securities, and net investments in direct financing leases, amongst other financial instruments. ASU 2016-13 also modifies the impairment model for available-for-sale debt securities and expands the disclosure requirements regarding an entity’s assumptions, models, and methods for estimating the allowance for losses. ASU 2016-13 will be effective for public business entities in fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early application of the guidance permitted. We are in the process of evaluating the impact of adopting ASU 2016-13 on our consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. ASU 2017-12 will make more financial and nonfinancial hedging strategies eligible for hedge accounting. It also amends the presentation and disclosure requirements and changes how companies assess hedge effectiveness. It is intended to more closely align hedge accounting with companies’ risk management strategies, simplify the application of hedge accounting, and increase transparency as to the scope and results of hedging programs. ASU 2017-12 will be effective in fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. We are in the process of evaluating the impact of adopting ASU 2017-12 on our consolidated financial statements, and expect to adopt the standard for the fiscal year beginning January 1, 2019.
Intangible Assets and Liabilities	Amortization of below-market rent and above-market rent intangibles is recorded as an adjustment to Rental income, amortization of below-market and above-market ground lease intangibles is included in Property expenses, and amortization of in-place lease intangibles is included in Depreciation and amortization expense in the consolidated financial statements.
Fair Value Measurements	Derivative Assets — Our derivative assets, which are included in Other assets, net in the consolidated financial statements, are comprised of foreign currency forward contracts, interest rate swaps, interest rate caps, and foreign currency collars (Note 8). These derivative instruments were measured at fair value using readily observable market inputs, such as quotations on interest rates, and were classified as Level 2 as these instruments are custom, over-the-counter contracts with various bank counterparties that are not traded in an active market. Derivative Liabilities — Our derivative liabilities, which are included in Accounts payable, accrued expenses and other liabilities in the consolidated financial statements, are comprised of interest rate swaps and foreign currency collars (Note 8). These derivative instruments were measured at fair value using readily observable market inputs, such as quotations on interest rates, and were classified as Level 2 because they are custom, over-the-counter contracts with various bank counterparties that are not traded in an active market. The fair value of an asset is defined as the exit price, which is the amount that would either be received when an asset is sold or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The guidance establishes a three-tier fair value hierarchy based on the inputs used in measuring fair value. These tiers are: Level 1, for which quoted market prices for identical instruments are available in active markets, such as money market funds, equity securities, and U.S. Treasury securities; Level 2, for which there are inputs other than quoted prices included within Level 1 that are observable for the instrument, such as certain derivative instruments including interest rate caps, interest rate swaps, foreign currency forward contracts and foreign currency collars; and Level 3, for securities that do not fall into Level 1 or Level 2 and for which little or no market data exists, therefore requiring us to develop our own assumptions.
Derivatives	We measure derivative instruments at fair value and record them as assets or liabilities, depending on our rights or obligations under the applicable derivative contract. Derivatives that are not designated as hedges must be adjusted to fair value through earnings. For a derivative designated, and that qualified, as a cash flow hedge, the effective portion of the change in fair value of the derivative is recognized in Other comprehensive income until the hedged item is recognized in earnings. For a derivative designated, and that qualified, as a net investment hedge, the effective portion of the change in its fair value and/or the net settlement of the derivative is reported in Other comprehensive income as part of the cumulative foreign currency translation adjustment. The ineffective portion of the change in fair value of any derivative is immediately recognized in earnings.