Description of Business, Basis of Presentation and Accounting Policies	6 Months Ended
Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business, Basis of Presentation and Accounting Policies	Description of Business, Basis of Presentation and Accounting Policies Business—American Tower Corporation is, through its various subsidiaries (collectively, “ATC” or the “Company”), one of the largest global real estate investment trusts and a leading independent owner, operator and developer of multitenant communications real estate. The Company’s primary business is the leasing of space on multitenant communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries. The Company also manages rooftop and tower sites for property owners, operates in-building and outdoor distributed antenna system (“DAS”) networks, holds property interests under third-party communications sites and provides network development services that primarily support its rental and management operations. ATC is a holding company that conducts its operations through its directly and indirectly owned subsidiaries and its joint ventures. ATC’s principal domestic operating subsidiaries are American Towers LLC and SpectraSite Communications, LLC. ATC conducts its international operations primarily through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international holding and operating subsidiaries and joint ventures. The Company operates as a real estate investment trust for U.S. federal income tax purposes (“REIT”) and, therefore, is generally not subject to U.S. federal income taxes on its income and gains that it distributes to its stockholders, including the income derived from leasing space on its towers. However, the Company remains obligated to pay income taxes on earnings from its taxable REIT subsidiaries (“TRSs”). In addition, the Company’s international assets and operations, including those designated as direct or indirect qualified REIT subsidiaries or other disregarded entities of a REIT (collectively, “QRSs”), continue to be subject to taxation in the foreign jurisdictions where those assets are held or those operations are conducted. As of June 30, 2015, the Company’s QRSs included its domestic tower leasing business, most of its operations in Costa Rica, Germany and Mexico and a majority of its network development services segment and indoor DAS networks business. On March 27, 2015, the Company significantly expanded its domestic portfolio by obtaining the exclusive right to lease, acquire or otherwise operate and manage 11,448 wireless communications sites from Verizon Communications Inc. (“Verizon”) in the United States (the “Verizon Transaction”). The accompanying condensed consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. The financial information included herein is unaudited; however, the Company believes that all adjustments (consisting primarily of normal recurring adjustments) considered necessary for a fair presentation of the Company’s financial position and results of operations for such periods have been included. These condensed consolidated financial statements and related notes should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 (the “2014 Form 10-K”). Principles of Consolidation and Basis of Presentation—The accompanying condensed consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity or cost method, depending upon the Company’s ability to exercise significant influence over operating and financial policies. All intercompany accounts and transactions have been eliminated. Significant Accounting Policies and Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying condensed consolidated financial statements. The significant estimates in the accompanying condensed consolidated financial statements include impairment of long-lived assets (including goodwill), asset retirement obligations, revenue recognition, rent expense, stock-based compensation, income taxes and accounting for business combinations and acquisitions of assets. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure. Accounting Standards Updates—In May 2014, the Financial Accounting Standards Board (the “FASB”) issued new revenue recognition guidance, which requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the transfer of promised goods or services to customers. The standard will replace most existing revenue recognition guidance in GAAP and will become effective on January 1, 2018. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method and leases are not included in the scope of this standard. The Company is evaluating the impact this standard will have on its financial statements. In June 2014, the FASB issued stock-based compensation guidance, which requires a performance target that could be achieved after the requisite service period be treated as a performance condition that affects vesting, rather than a condition that affects the grant-date fair value. The Company early adopted this guidance on a prospective basis during the six months ended June 30, 2015, and it did not have a material effect on the Company’s financial statements. In April 2015, the FASB issued new guidance on the presentation of debt issuance costs. The guidance requires debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of the related debt liability, consistent with debt discounts and premiums. The update requires retrospective application and the update is effective for annual reporting periods beginning after December 15, 2015. The Company does not expect the adoption of this guidance to have a material effect on its financial statements.

Description of Business, Basis of Presentation and Accounting Policies

Business—American Tower Corporation is, through its various subsidiaries (collectively, “ATC” or the “Company”), one of the largest global real estate investment trusts and a leading independent owner, operator and developer of multitenant communications real estate. The Company’s primary business is the leasing of space on multitenant communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries. The Company also manages rooftop and tower sites for property owners, operates in-building and outdoor distributed antenna system (“DAS”) networks, holds property interests under third-party communications sites and provides network development services that primarily support its rental and management operations.

ATC is a holding company that conducts its operations through its directly and indirectly owned subsidiaries and its joint ventures. ATC’s principal domestic operating subsidiaries are American Towers LLC and SpectraSite Communications, LLC. ATC conducts its international operations primarily through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international holding and operating subsidiaries and joint ventures.

The Company operates as a real estate investment trust for U.S. federal income tax purposes (“REIT”) and, therefore, is generally not subject to U.S. federal income taxes on its income and gains that it distributes to its stockholders, including the income derived from leasing space on its towers. However, the Company remains obligated to pay income taxes on earnings from its taxable REIT subsidiaries (“TRSs”). In addition, the Company’s international assets and operations, including those designated as direct or indirect qualified REIT subsidiaries or other disregarded entities of a REIT (collectively, “QRSs”), continue to be subject to taxation in the foreign jurisdictions where those assets are held or those operations are conducted. As of June 30, 2015, the Company’s QRSs included its domestic tower leasing business, most of its operations in Costa Rica, Germany and Mexico and a majority of its network development services segment and indoor DAS networks business.

On March 27, 2015, the Company significantly expanded its domestic portfolio by obtaining the exclusive right to lease, acquire or otherwise operate and manage 11,448 wireless communications sites from Verizon Communications Inc. (“Verizon”) in the United States (the “Verizon Transaction”).

The accompanying condensed consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. The financial information included herein is unaudited; however, the Company believes that all adjustments (consisting primarily of normal recurring adjustments) considered necessary for a fair presentation of the Company’s financial position and results of operations for such periods have been included. These condensed consolidated financial statements and related notes should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 (the “2014 Form 10-K”).

Principles of Consolidation and Basis of Presentation—The accompanying condensed consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity or cost method, depending upon the Company’s ability to exercise significant influence over operating and financial policies. All intercompany accounts and transactions have been eliminated.

Significant Accounting Policies and Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying condensed consolidated financial statements. The significant estimates in the accompanying condensed consolidated financial statements include impairment of long-lived assets (including goodwill), asset retirement obligations, revenue recognition, rent expense, stock-based compensation, income taxes and accounting for business combinations and acquisitions of assets. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure.

Accounting Standards Updates—In May 2014, the Financial Accounting Standards Board (the “FASB”) issued new revenue recognition guidance, which requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the transfer of promised goods or services to customers. The standard will replace most existing revenue recognition guidance in GAAP and will become effective on January 1, 2018. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method and leases are not included in the scope of this standard. The Company is evaluating the impact this standard will have on its financial statements.

In June 2014, the FASB issued stock-based compensation guidance, which requires a performance target that could be achieved after the requisite service period be treated as a performance condition that affects vesting, rather than a condition that affects the grant-date fair value. The Company early adopted this guidance on a prospective basis during the six months ended June 30, 2015, and it did not have a material effect on the Company’s financial statements.

In April 2015, the FASB issued new guidance on the presentation of debt issuance costs. The guidance requires debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of the related debt liability, consistent with debt discounts and premiums. The update requires retrospective application and the update is effective for annual reporting periods beginning after December 15, 2015. The Company does not expect the adoption of this guidance to have a material effect on its financial statements.