Description of Business and Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation — The Condensed Consolidated Financial Statements of the Company have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) and, in the opinion of management, include all adjustments necessary for a fair presentation of the results of operations, other comprehensive income, financial position and cash flows for each period presented. The adjustments referred to above are of a normal and recurring nature. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to SEC rules and regulations for interim reporting. The Condensed Consolidated Balance Sheet as of December 31, 2015 was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. These Condensed Consolidated Financial Statements should be read in conjunction with the Company’s 2015 Annual Report on Form 10-K. Operating results for the three months ended March 31, 2016 are not necessarily indicative of the results expected for the full year or any other interim period. The closing of our wireless operations in March 2015 represented a strategic shift in our business. Therefore, certain wireless assets, liabilities and results of operations are reported as discontinued operations in our financial statements. See Note 9 for all required disclosures.
Use of Estimates	Use of Estimates — Preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported. Actual results could differ from those estimates. In the normal course of business, the Company is subject to various regulatory and tax proceedings, lawsuits, claims and other matters. The Company believes adequate provision has been made for all such asserted and unasserted claims in accordance with U.S. GAAP. Such matters are subject to many uncertainties and outcomes that are not predictable with assurance.
Restructuring Liability	Restructuring Liability — As of March 31, 2016, restructuring liabilities have been established for employee separations, lease abandonments and other charges. As of March 31, 2016 and December 31, 2015, $0.9 million of the restructuring liabilities was included in “Other current liabilities,” and $0.2 million was included in “Other noncurrent liabilities” in the Condensed Consolidated Balance Sheets.
Income Taxes	Income Taxes — The Company’s income tax provision for interim periods is determined through the use of an estimated annual effective tax rate applied to year-to-date ordinary income, as well as the tax effects associated with discrete items. The Company expects its effective rate to exceed statutory rates primarily due to non-deductible expenses.
Recently Issued Accounting Standards	Recently Issued Accounting Standards — In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-09, Compensation - Stock Compensation, which simplifies various aspects related to how share-based payments are accounted for and presented in the financial statements. The new standard is effective for public business entities for annual reporting periods beginning after December 15, 2016. The Company is currently in the process of evaluating the impact of adoption of this ASU on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases, which represents a wholesale change to lease accounting. The standard introduces a lessee model that brings most leases on the balance sheet as well as aligning certain underlying principles of the new lessor model with those in Accounting Standards Codification ("ASC") 606. The new standard is effective for public business entities for fiscal years beginning after December 15, 2018 and lessees and lessors are required to use a modified retrospective transition method for existing leases. The Company is currently in the process of evaluating the impact of adoption of this ASU on the Company’s consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which amends the guidance in U.S. GAAP on the classification and measurement of financial instruments, in January 2016. The amended guidance requires entities to carry all investments in equity securities at fair value through net income unless the entity has elected the practicability exception to fair value measurement. This standard will be effective for the fiscal year ending December 31, 2018 and will require a cumulative-effect adjustment to beginning retained earnings on this date. The Company is currently in the process of evaluating the impact of adoption of this ASU on the Company's consolidated financial statements. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, which changes the presentation of debt issuance costs in the financial statements. Specifically, this amendment requires that costs associated with the issuance of debt be presented on the balance sheet as a direct deduction from the related debt liability. The Company retrospectively adopted the amended standard effective January 1, 2016. The adoption resulted in a prior period adjustment due to a change in accounting principle. The Condensed Consolidated Balance Sheet for the period ending December 31, 2015 has been restated to reflect this change in accounting principle. Note issuance costs of $8.0 million were reclassed from “Other noncurrent assets” to “Long-term debt, less current portion.” Note 3 has been updated to reflect the adjustment. On the effective date of ASU 2015-03, the Company made a one-time policy election to record costs incurred in connection with obtaining revolving credit agreements as an asset and to amortize these costs ratably over the term of the agreement. This accounting treatment is consistent with how deferred financing costs were accounted for prior to adoption of ASU 2015-03. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. This standard also includes expanded disclosure requirements that result in an entity providing users of financial statements with comprehensive information about the nature, amount, timing, and uncertainty of revenue and cash flows arising from the entity’s contracts with customers. In August 2015, ASU 2015-14 was issued deferring the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017 with an optional early application date for annual reporting periods beginning after December 15, 2016. The Company has elected to adopt the standard in the first quarter of the fiscal year ending December 31, 2018. The Company is continuing to evaluate the impact of adoption of this ASU on the Company’s consolidated financial statements. No other new accounting pronouncement issued or effective during the year had, or is expected to have, a material impact on the consolidated financial statements.
Earnings Per Share	Basic earnings per common share (“EPS”) is based upon the weighted average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that would occur upon issuance of common shares for awards under stock-based compensation plans, exercise of warrants or conversion of preferred stock, but only to the extent that they are considered dilutive.
Fair Value Measurement	The fair value of our investment in CyrusOne was based on the closing market price of CyrusOne's common stock on March 31, 2016 and December 31, 2015. This fair value measurement is considered Level 1 of the fair value hierarchy. The fair value of our long-term debt was based on closing or estimated market prices of the Company’s debt at March 31, 2016 and December 31, 2015, which is considered Level 2 of the fair value hierarchy.

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.