Summary of Significant Accounting Policies (Policy)	9 Months Ended
Summary of Significant Accounting Policies (Policy)	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the balance sheet and revenues and expenses for the period. Actual results could differ significantly from those estimates. In addition, operating results for the nine month period ended September 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. The Company consolidates certain entities when it is deemed to be the primary beneficiary in a variable interest entity (VIE) in which it has a controlling financial interest in accordance with the consolidation guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC). The consolidated balance sheet as of December 31, 2017 has been derived from the audited consolidated balance sheet at that date but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. For further information, refer to the consolidated financial statements and footnotes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 filed with the Securities and Exchange Commission (SEC) on March 1, 2018.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Recently Adopted Accounting Pronouncements On January 1, 2018, the Company adopted Accounting Standards Update (ASU) No. 2016-18, Statement of Cash Flows, and certain reclassifications have been made to prior period balances to conform to current presentation in the consolidated statement of cash flows. Under ASU No. 2016-18, transfers to or from restricted cash which have been previously shown in the Company's operating activities section of the accompanying consolidated statement of cash flows are now required to be shown as part of the total change in cash and cash equivalents and restricted cash in the consolidated statements of cash flows. In addition, on January 1, 2018, the Company adopted ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments. The ASU clarifies the treatment of several cash flow issues with the objective of reducing diversity in practice. The adoption of this ASU had no impact to the Company's financial position, results of operations or presentation in the consolidated statement of cash flows. On January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers (ASC 606) and ASC Topic 610-20, Other Income: Gains and Losses from the Derecognition of Non-financial Assets (ASC 610-20) using a modified retrospective (cumulative effect) method of adoption. The core principle of ASC 606 is that an entity will recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers when it satisfies performance obligations. The Company’s primary source of revenue is from lease revenue (which is excluded from the revenue standard but will be impacted upon adoption of the lease standard in 2019 discussed in Impact of Recently Issued Accounting Standards) and mortgage and other financing income (which is not in scope of the revenue standard). ASC 610-20 provides guidance on how entities recognize sales to non-customers including presentation of gain or loss on a net basis in the consolidated statements of income. The Company has concluded that its property sales represent transactions with non-customers. The Company had two property sale transactions that occurred in 2017 in which the Company received an aggregate of $12.3 million in mortgage notes receivable as full consideration for the sales. The mortgage notes require interest only payments until maturity and the Company determined in 2017 that these transactions qualified as sales; however, the gain on each sale was deferred. Upon adoption of ASC 610-20 on January 1, 2018, the Company determined that these transactions did not qualify for de-recognition. Accordingly, the Company recorded an adjustment in the nine months ended September 30, 2018 to reclassify these assets from mortgage notes receivable to rental properties on its consolidated balance sheet. All other sales of real estate were all cash transactions in which the purchaser obtained control of the property, therefore, there was no cumulative adjustment recognized to beginning retained earnings as a result of adopting ASC 610-20.
Operating Segments	Operating Segments The Company has four reportable operating segments: Entertainment, Recreation, Education and Other. See Note 15 for financial information related to these operating segments.
Rental Properties	Rental Properties Rental properties are carried at cost less accumulated depreciation. Costs incurred for the acquisition and development of the properties are capitalized. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which generally are estimated to be 30 to 40 years for buildings and three to 25 years for furniture, fixtures and equipment and 10 to 20 years for site improvements. Tenant improvements, including allowances, are depreciated over the shorter of the base term of the lease or the estimated useful life and leasehold interests are depreciated over the useful life of the underlying ground lease. Expenditures for ordinary maintenance and repairs are charged to operations in the period incurred. Significant renovations and improvements that improve or extend the useful life of the asset are capitalized and depreciated over their estimated useful life. Management reviews a property for impairment whenever events or changes in circumstances indicate that the carrying value of a property may not be recoverable. The review of recoverability is based on an estimate of undiscounted future cash flows expected to result from its use and eventual disposition. If impairment exists due to the inability to recover the carrying value of the property, an impairment loss is recorded to the extent that the carrying value of the property exceeds its estimated fair value. The Company evaluates the held-for-sale classification of its real estate as of the end of each quarter. Assets that are classified as held for sale are recorded at the lower of their carrying amount or fair value less costs to sell. Assets are generally classified as held for sale once management has initiated an active program to market them for sale and it is probable the assets will be sold within one year. On occasion, the Company will receive unsolicited offers from third parties to buy individual Company properties. Under these circumstances, the Company will classify the properties as held for sale when a sales contract is executed with no contingencies and the prospective buyer has funds at risk to ensure performance.
Business Combinations and Other Purchase of Business Transactions, Policy [Policy Text Block]	Upon acquisition of real estate properties, the Company evaluates the acquisition to determine if it is a business combination or an asset acquisition. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The update clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether acquisitions should be accounted for as business combinations or asset acquisitions. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those fiscal years, with early application of the guidance permitted. The Company elected to early adopt ASU No. 2017-01 as of January 1, 2017. As a result, the Company expects that fewer of its real estate acquisitions will be accounted for as business combinations. Costs incurred for asset acquisitions and development properties, including transaction costs, are capitalized. For asset acquisitions, the Company allocates the purchase price and other related costs incurred to the acquired tangible assets and identified intangible assets and liabilities based on recent independent appraisals or methods similar to those used by independent appraisers and management judgment. Acquisition-related costs in connection with business combinations are expensed as incurred. Costs related to such transactions, as well as costs associated with terminated transactions, are included in the accompanying consolidated statements of income as transaction costs.
Deferred Charges, Policy [Policy Text Block]	Deferred Financing Costs Deferred financing costs are amortized over the terms of the related debt obligations or mortgage note receivable as applicable. Deferred financing costs of $35.0 million and $32.9 million as of September 30, 2018 and December 31, 2017, respectively, are shown as a reduction of debt. The deferred financing costs related to the unsecured revolving credit facility are included in other assets.
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts Accounts receivable is reduced by an allowance for amounts where collection is not probable. The Company’s accounts receivable balance is comprised primarily of rents and operating cost recoveries due from tenants as well as accrued rental rate increases to be received over the life of the existing leases. The Company regularly evaluates the adequacy of its allowance for doubtful accounts. The evaluation primarily consists of reviewing past due account balances and considering such factors as the credit quality of the Company’s tenants, historical trends of the tenant and/or other debtor, current economic conditions and changes in customer payment terms. Additionally, with respect to tenants in bankruptcy, the Company estimates the expected recovery through bankruptcy claims and increases the allowance for amounts deemed uncollectible. These estimates have a direct impact on the Company's net income.
Revenue Recognition	Revenue Recognition Rents that are fixed and determinable are recognized on a straight-line basis over the non-cancellable terms of the leases. Straight-line rental revenue is subject to an evaluation for collectability, and the Company records a provision for losses against rental revenues if collectability of these future rents is not reasonably assured. For the nine months ended September 30, 2018 and 2017, the Company recognized $7.0 million and $11.4 million, respectively, of straight-line rental revenue. Base rent escalation on leases that are dependent upon increases in the Consumer Price Index (CPI) is recognized when known. For both the nine months ended September 30, 2018 and 2017, the Company recognized $11.4 million of tenant reimbursements that related to the operations of its entertainment retail centers. Certain reclassifications have been made to the 2017 presentation to conform to the 2018 presentation to combine tenant reimbursements with rental revenue. In addition, most of the Company's tenants are subject to additional rents if gross revenues of the properties exceed certain thresholds defined in the lease agreements (percentage rents). Percentage rents as well as participating interest for those mortgage agreements that contain similar such clauses are recognized at the time when specific triggering events occur as provided by the lease or mortgage agreements. Rental revenue included percentage rents of $5.7 million and $4.7 million for the nine months ended September 30, 2018 and 2017, respectively. Mortgage and other financing income included participating interest income of $0.7 million for the nine months ended September 30, 2017. No participating interest income was recognized for the nine months ended September 30, 2018. Direct financing lease income is recognized on the effective interest method to produce a level yield on funds not yet recovered. Estimated unguaranteed residual values at the date of lease inception represent management's initial estimates of fair value of the leased assets at the expiration of the lease, not to exceed original cost. Significant assumptions used in estimating residual values include estimated net cash flows over the remaining lease term and expected future real estate values. The Company evaluates on an annual basis (or more frequently, if necessary) the collectability of its direct financing lease receivable and unguaranteed residual value to determine whether they are impaired. A direct financing lease receivable is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the existing contractual terms. When a direct financing lease receivable is considered to be impaired, the amount of loss is calculated by comparing the recorded investment to the value determined by discounting the expected future cash flows at the direct financing lease receivable's effective interest rate or to the fair value of the underlying collateral, less costs to sell, if such receivable is collateralized.
Property Sales, Policy [Policy Text Block]	Property Sales Sales of real estate properties are recognized when a contract exists, collectability is probable and the purchaser has obtained control of the property. Gains on sales of properties are recognized in full in a partial sale of nonfinancial assets, to the extent control is not retained. Any noncontrolling interest retained by the seller would, accordingly, be measured at fair value. The Company evaluates each sale or disposal transaction to determine if it meets the criteria to qualify as discontinued operations. A discontinued operation is a component of an entity or group of components that have been disposed of or are classified as held for sale and represent a strategic shift that has or will have a major effect on the Company's operations and financial results. If the sale or disposal transaction does not meet the criteria, the operations and related gain or loss on sale is included in income from continuing operations.
Mortgage Notes And Other Notes Receivable	Mortgage Notes and Other Notes Receivable Mortgage notes and other notes receivable, including related accrued interest receivable, consist of loans originated by the Company and the related accrued and unpaid interest income as of the balance sheet date. Mortgage notes and other notes receivable are initially recorded at the amount advanced to the borrower. Interest income is recognized using the effective interest method based on the stated interest rate over the estimated life of the note. Premiums and discounts are amortized or accreted into income over the estimated life of the note using the effective interest method. The Company evaluates the collectability of both interest and principal of each of its loans to determine whether it is impaired. A loan is considered to be impaired when, based on current information and events, the Company determines that it is probable that it will be unable to collect all amounts due according to the existing contractual terms. An insignificant delay or shortfall in amounts of payments does not necessarily result in the loan being identified as impaired. When a loan is considered to be impaired, the amount of loss, if any, is calculated by comparing the recorded investment to the value determined by discounting the expected future cash flows at the loan’s effective interest rate or to the fair value of the Company’s interest in the underlying collateral, less costs to sell, if the loan is collateral dependent. For impaired loans, interest income is recognized on a cash basis, unless the Company determines based on the loan to estimated fair value ratio the loan should be on the cost recovery method, and any cash payments received would then be reflected as a reduction of principal. Interest income recognition is recommenced if and when the impaired loan becomes contractually current and performance is demonstrated to be resumed.
Concentrations Of Risk	Concentrations of Risk American Multi-Cinema, Inc. (AMC) was the lessee of a substantial portion (34%) of the megaplex theatre rental properties held by the Company at September 30, 2018. For the nine months ended September 30, 2018 and 2017, approximately $86.3 million or 16.2% and $85.7 million or 20.0%, respectively, of the Company's total revenues were derived from rental payments by AMC. These rental payments are from AMC under the leases, or from its parent, AMC Entertainment, Inc. (AMCE), as the guarantor of AMC’s obligations under the leases. AMCE is wholly owned by AMC Entertainment Holdings, Inc. (AMCEH). AMCEH is a publicly held company (NYSE: AMC) and its consolidated financial information is publicly available at www.sec.gov.
Share-Based Compensation	Share-Based Compensation Share-based compensation to employees of the Company is granted pursuant to the Company's Annual Incentive Program and Long-Term Incentive Plan and share-based compensation to non-employee Trustees of the Company is granted pursuant to the Company's Trustee compensation program. Prior to May 12, 2016, share-based compensation granted to employees and non-employee Trustees was issued under the 2007 Equity Incentive Plan. The 2016 Equity Incentive Plan was approved by shareholders at the May 11, 2016 annual shareholder meeting and this plan replaced the 2007 Equity Incentive Plan. Accordingly, all share-based compensation granted on or after May 12, 2016 has been issued under the 2016 Equity Incentive Plan. Share-based compensation expense consists of share option expense and amortization of nonvested share grants issued to employees, and amortization of share units issued to non-employee Trustees for payment of their annual retainers. Share-based compensation included in general and administrative expense in the accompanying consolidated statements of income totaled $11.3 million and $10.6 million for the nine months ended September 30, 2018 and 2017, respectively.
Share Options	Share Options Share options are granted to employees pursuant to the Long-Term Incentive Plan. The fair value of share options granted is estimated at the date of grant using the Black-Scholes option pricing model. Share options granted to employees vest over a period of four years and share option expense for these options is recognized on a straight-line basis over the vesting period. Expense recognized related to share options and included in general and administrative expense in the accompanying consolidated statements of income was $213 thousand and $528 thousand for the nine months ended September 30, 2018 and 2017, respectively.
Nonvested Shares Issued To Employees	Nonvested Shares Issued to Employees The Company grants nonvested shares to employees pursuant to both the Annual Incentive Program and the Long-Term Incentive Plan. The Company amortizes the expense related to the nonvested shares awarded to employees under the Long-Term Incentive Plan and the premium awarded under the nonvested share alternative of the Annual Incentive Program on a straight-line basis over the future vesting period (three or four years). Expense recognized related to nonvested shares and included in general and administrative expense in the accompanying consolidated statements of income was $10.2 million and $9.1 million for the nine months ended September 30, 2018 and 2017, respectively.
Restricted Share Units Issued To Non-Employee Trustees	Restricted Share Units Issued to Non-Employee Trustees The Company issues restricted share units to non-employee Trustees for payment of their annual retainers under the Company's Trustee compensation program. The fair value of the share units granted was based on the share price at the date of grant. The share units vest upon the earlier of the day preceding the next annual meeting of shareholders or a change of control. The settlement date for the shares is selected by the non-employee Trustee, and ranges from one year from the grant date to upon termination of service. This expense is amortized by the Company on a straight-line basis over the year of service by the non-employee Trustees. Total expense recognized related to shares issued to non-employee Trustees was $931 thousand and $936 thousand for the nine months ended September 30, 2018 and 2017, respectively.
Derivative Instruments	Derivative Instruments In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The update amended existing guidance in order to better align a company's financial reporting for hedging activities with the economic objectives of those activities. It requires the Company to disclose the effect of its hedging activities on its consolidated statements of income and eliminated the periodic measurement and recognition of hedging ineffectiveness. The standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years, with early application of the guidance permitted. The Company elected to early adopt ASU No. 2017-12 as of October 1, 2017. Early adoption had no impact on the Company's financial position or results of operations. The Company has entered into certain derivative instruments to reduce exposure to fluctuations in foreign currency exchange rates and variable interest rates. The Company has established policies and procedures for risk assessment and the approval, reporting and monitoring of derivative financial instrument activities. These derivatives consist of foreign currency forward contracts, cross-currency swaps and interest rate swaps. The Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. Derivatives may also be designated as hedges of the foreign currency exposure of a net investment in a foreign operation. For its net investment hedges, the Company has elected to assesses hedge effectiveness using a method based on changes in spot exchange rates and record the changes in the fair value amounts excluded from the assessment of effectiveness into earnings on a systematic and rational basis. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. The Company's policy is to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio.
New Accounting Pronouncements, Policy [Policy Text Block]	Impact of Recently Issued Accounting Standards In February 2016, the FASB issued ASU No. 2016-02, Leases, which amends existing accounting standards for lease accounting and is intended to improve financial reporting related to lease transactions. The ASU will require lessees to classify leases as either finance or operating leases based on certain criteria and to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. Lessor accounting will remain largely unchanged from current U.S. GAAP. The standard eliminates current real estate-specific provisions and changes the guidance on sale-leaseback transactions and will require new disclosures within the notes accompanying the consolidated financial statements. Although the Company is primarily a lessor, ASU No. 2016-02 will impact the Company’s consolidated financial statements and disclosures as it has certain operating land leases and other arrangements for which it is the lessee and will be required to recognize these arrangements on the consolidated financial statements. For the land lease arrangements, the Company is also, in substantially all cases, in a sub-lessor position and passes the obligation to pay the monthly land lease payments on to its sublessees. The Company has completed its initial inventory and evaluation of the land leases and other arrangements and expects that it will be required to recognize a right-of-use asset and a lease liability for the present value of the minimum lease payments. The Company is in the process of preparing the initial estimates of the amount of its right-of-use assets and lease liabilities. Based on the current contracts under which the Company is a lessee, it is estimated that its right-of-use assets and lease liabilities to be recognized upon adoption will be less than 4% of total assets. However, the ultimate impact of adopting ASU No. 2016-02 will depend on the Company’s lease portfolio as of the adoption date. A substantial portion of the Company’s lease contracts (under which it is lessor) are triple-net leases, which require the tenants to make payments to third parties for operating expenses such as property taxes, insurance and common area maintenance costs associated with the properties. The Company currently does not include these payments made by the lessee to third parties in rental revenue or property operating expenses. Because of applying the guidance in ASU No. 2016-02, the Company may be required to show certain payments made by its tenants on a gross basis in its consolidated statements of income. Although no impact to net income or cash flows is expected as a result of a gross presentation, it may have the impact of increasing both reported revenues and property operating expenses. The Company is continuing to evaluate the impact of this potential presentation. The ASU will become effective for the Company for interim and annual reporting periods in fiscal years beginning after December 15, 2018. The Company expects to adopt the new standard on its effective date. The standard offers several practical expedients for transition and certain expedients specific to lessees or lessors. Both lessees and lessors are permitted to make an election to apply a package of practical expedients available for implementation under the standard. The Company has concluded it will apply the package of practical expedients and certain other transition expedients, including the expedient to not evaluate existing or expired land easements. For transition, the Company intends to recognize all effects of transition in the beginning of the adoption reporting period on January 1, 2019. The Company will continue its implementation work in 2018 including enhancements to the Company’s internal control framework, accounting systems and related documentation surrounding its lease accounting processes and the preparation of any additional disclosures that will be required. In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments, which amends ASC Topic 326, Financial Instruments - Credit Losses. The ASU changes the methodology for measuring credit losses on financial instruments and timing of when such losses are recorded. The amendments in ASU No. 2016-13 require the Company to measure all expected credit losses based upon historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of financial assets and eliminates the incurred losses methodology under current U.S. GAAP. ASU No. 2016-13 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. The Company is currently evaluating the impact that the ASU will have on its consolidated financial statements and related disclosures.