Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies There have been no material changes to the summary of significant accounting policies included in the section entitled "Summary of Significant Accounting Policies" beginning on page F-11 of our December 31, 2014 Annual Report on Form 10-K. Please review the Summary of Significant Accounting Policies set forth in our December 31, 2014 Annual Report on Form 10-K, which is incorporated herein by reference. Basis of Quarterly Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), for interim financial information, and with the rules and regulations of the Securities and Exchange Commission (the "SEC"). Accordingly, certain information and footnote disclosures required by GAAP for complete financial statements have been condensed or omitted in accordance with such rules and regulations. In the opinion of management, all adjustments and eliminations (including intercompany balances and transactions), consisting of normal recurring adjustments, considered necessary for the fair presentation of the financial statements have been included. For purposes of comparison, certain items shown in the 2014 unaudited condensed consolidated financial statements have been reclassified to conform to the presentation used for 2015. The results of operations for the periods presented are not necessarily indicative of the results that may be expected for the corresponding full years. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the financial statements for the year ended December 31, 2014 contained in our Annual Report on Form 10-K. We do not consider our business to be subject to material seasonal fluctuations, except that our observatory business is subject to tourism seasonality. During the past ten years of our annual observatory revenue, approximately 16.0% to 18.0% was realized in the first quarter, 26.0% to 28.0% was realized in the second quarter, 31.0% to 33.0% was realized in the third quarter and 23.0% to 25.0% was realized in the fourth quarter. The primary beneficiary of a variable interest entity ("VIE") is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE, and has the requirement to consolidate the VIE. We had no VIEs as of March 31, 2015 and December 31, 2014. We will assess the accounting treatment for each investment we may have in the future. This assessment will include a review of each entity’s organizational agreement to determine which party has what rights and whether those rights are protective or participating. For all VIEs, we will review such agreements in order to determine which party has the power to direct the activities that most significantly impact the entity’s economic performance and benefit. In situations where we or our partner could approve, among other things, the annual budget, the entity’s tax return before filing, and leases that cover more than a nominal amount of space relative to the total rentable space at each property, we would not consolidate the investment as we consider these to be substantive participation rights that result in shared power of the activities that would most significantly impact the performance and benefit of such joint venture investment. Such agreements could also contain certain protective rights such as the requirement of partner approval to sell, finance or refinance the investment and the payment of capital expenditures and operating expenditures outside of the approved budget or operating plan. A non-controlling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to a parent. Non-controlling interests are required to be presented as a separate component of equity in the condensed consolidated balance sheets and in the condensed consolidated statements of income by requiring earnings and other comprehensive income to be attributed to controlling and non-controlling interests. Accounting Estimates The preparation of the condensed consolidated financial statements in accordance with GAAP requires management to use estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported revenues and expenses. Significant items subject to such estimates and assumptions include allocation of the purchase price of acquired real estate properties among tangible and intangible assets, determination of the useful life of real estate properties and other long-lived assets, valuation and impairment analysis of commercial real estate properties and other long-lived assets, estimate of percentage of completion on construction contracts, valuation of the allowance for doubtful accounts, and valuation of exchangeable senior unsecured notes and equity based compensation. These estimates are prepared using management’s best judgment, after considering past, current, and expected events and economic conditions. Actual results could differ from those estimates. Recently Issued or Adopted Accounting Standards During April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs, which amends the requirements for the presentation of debt issuance costs and requires that that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years, beginning after December 15, 2015 and interim periods within those fiscal years. The implementation of this update is not expected to cause any material changes to our consolidated financial statements other than the reclassification of debt issuance costs from assets to liabilities on our Consolidated Balance Sheets. During February 2015, the FASB issued ASU 2015-02, Consolidation (Topic 810) - Amendments to the Consolidation Analysis, which amends the criteria for determining which entities are considered VIEs, amends the criteria for determining if a service provider possesses a variable interest in a VIE and ends the deferral granted to investment companies for application of the VIE consolidation model. ASU 2015-02 is effective for annual periods, and interim periods therein, beginning after December 15, 2015. We are evaluating the impact of adopting this new accounting standard on our financial statements. During January 2015, the FASB issued ASU No. 2015-01 Income Statement - Extraordinary and Unusual Items, which eliminates the concept of extraordinary items. However, the presentation and disclosure requirements for items that are either unusual or in nature or infrequent in occurrence remain and will be expanded to include items that are both unusual in nature and infrequent in occurrence. ASU 2015-01 is effective for periods beginning after December 15, 2015. We are evaluating the impact of adopting this new accounting standard on our financial statements. During May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers, which will replace all current GAAP guidance related to revenue recognition and eliminate all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective beginning in 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. We are evaluating the impact of adopting this new accounting standard on our financial statements. During April 2014, the FASB issued ASU No. 2014-08 Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the definition of a discontinued operation to include only those disposals of components of an entity that represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. This guidance is effective prospectively for fiscal years beginning after December 15, 2014. The adoption of ASU 2014-08 did not have a material impact on our financial statements.

Summary of Significant Accounting Policies

There have been no material changes to the summary of significant accounting policies included in the section entitled "Summary of Significant Accounting Policies" beginning on page F-11 of our December 31, 2014 Annual Report on Form 10-K. Please review the Summary of Significant Accounting Policies set forth in our December 31, 2014 Annual Report on Form 10-K, which is incorporated herein by reference.

Basis of Quarterly Presentation and Principles of Consolidation

The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), for interim financial information, and with the rules and regulations of the Securities and Exchange Commission (the "SEC"). Accordingly, certain information and footnote disclosures required by GAAP for complete financial statements have been condensed or omitted in accordance with such rules and regulations. In the opinion of management, all adjustments and eliminations (including intercompany balances and transactions), consisting of normal recurring adjustments, considered necessary for the fair presentation of the financial statements have been included. For purposes of comparison, certain items shown in the 2014 unaudited condensed consolidated financial statements have been reclassified to conform to the presentation used for 2015.

The results of operations for the periods presented are not necessarily indicative of the results that may be expected for the corresponding full years. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the financial statements for the year ended December 31, 2014 contained in our Annual Report on Form 10-K. We do not consider our business to be subject to material seasonal fluctuations, except that our observatory business is subject to tourism seasonality. During the past ten years of our annual observatory revenue, approximately 16.0% to 18.0% was realized in the first quarter, 26.0% to 28.0% was realized in the second quarter, 31.0% to 33.0% was realized in the third quarter and 23.0% to 25.0% was realized in the fourth quarter.

The primary beneficiary of a variable interest entity ("VIE") is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE, and has the requirement to consolidate the VIE. We had no VIEs as of March 31, 2015 and December 31, 2014.

We will assess the accounting treatment for each investment we may have in the future. This assessment will include a review of each entity’s organizational agreement to determine which party has what rights and whether those rights are protective or participating. For all VIEs, we will review such agreements in order to determine which party has the power to direct the activities that most significantly impact the entity’s economic performance and benefit. In situations where we or our partner could approve, among other things, the annual budget, the entity’s tax return before filing, and leases that cover more than a nominal amount of space relative to the total rentable space at each property, we would not consolidate the investment as we consider these to be substantive participation rights that result in shared power of the activities that would most significantly impact the performance and benefit of such joint venture investment. Such agreements could also contain certain protective rights such as the requirement of partner approval to sell, finance or refinance the investment and the payment of capital expenditures and operating expenditures outside of the approved budget or operating plan.

A non-controlling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to a parent. Non-controlling interests are required to be presented as a separate component of equity in the condensed consolidated balance sheets and in the condensed consolidated statements of income by requiring earnings and other comprehensive income to be attributed to controlling and non-controlling interests.

Accounting Estimates

The preparation of the condensed consolidated financial statements in accordance with GAAP requires management to use estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported revenues and expenses. Significant items subject to such estimates and assumptions include allocation of the purchase price of acquired real estate properties among tangible and intangible assets, determination of the useful life of real estate properties and other long-lived assets, valuation and impairment analysis of commercial real estate properties and other long-lived assets, estimate of percentage of completion on construction contracts, valuation of the allowance for doubtful accounts, and valuation of exchangeable senior unsecured notes and equity based compensation. These estimates are prepared using management’s best judgment, after considering past, current, and expected events and economic conditions. Actual results could differ from those estimates.

Recently Issued or Adopted Accounting Standards

During April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs, which amends the requirements for the presentation of debt issuance costs and requires that that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years, beginning after December 15, 2015 and interim periods within those fiscal years. The implementation of this update is not expected to cause any material changes to our consolidated financial statements other than the reclassification of debt issuance costs from assets to liabilities on our Consolidated Balance Sheets.

During February 2015, the FASB issued ASU 2015-02, Consolidation (Topic 810) - Amendments to the Consolidation Analysis, which amends the criteria for determining which entities are considered VIEs, amends the criteria for determining if a service provider possesses a variable interest in a VIE and ends the deferral granted to investment companies for application of the VIE consolidation model. ASU 2015-02 is effective for annual periods, and interim periods therein, beginning after December 15, 2015. We are evaluating the impact of adopting this new accounting standard on our financial statements.

During January 2015, the FASB issued ASU No. 2015-01 Income Statement - Extraordinary and Unusual Items, which eliminates the concept of extraordinary items. However, the presentation and disclosure requirements for items that are either unusual or in nature or infrequent in occurrence remain and will be expanded to include items that are both unusual in nature and infrequent in occurrence. ASU 2015-01 is effective for periods beginning after December 15, 2015. We are evaluating the impact of adopting this new accounting standard on our financial statements.

During May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers, which will replace all current GAAP guidance related to revenue recognition and eliminate all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective beginning in 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. We are evaluating the impact of adopting this new accounting standard on our financial statements.

During April 2014, the FASB issued ASU No. 2014-08 Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the definition of a discontinued operation to include only those disposals of components of an entity that represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. This guidance is effective prospectively for fiscal years beginning after December 15, 2014. The adoption of ASU 2014-08 did not have a material impact on our financial statements.