Organization and Summary of Significant Accounting Policies (Notes)	3 Months Ended
Mar. 31, 2017
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	(1) Organization and Summary of Significant Accounting Policies Description of Business Level 3 Communications, Inc. and subsidiaries is a facilities-based provider (that is, a provider that owns or leases a substantial portion of the plant, property and equipment necessary to provide our services) of a broad range of integrated communications services. We created our communications network by constructing our own assets and through a combination of purchasing other companies and purchasing or leasing facilities from others. Our network is an international, facilities-based communications network. We designed our network to provide communications services that employ and take advantage of rapidly improving underlying optical, Internet Protocol, computing and storage technologies. On October 31, 2016, we entered into an agreement and plan of merger (the "Merger Agreement") with CenturyLink, Inc., a Louisiana corporation ("CenturyLink"), Wildcat Merger Sub 1 LLC, a Delaware limited liability company and an indirect wholly owned subsidiary of CenturyLink ("Merger Sub 1"), and WWG Merger Sub LLC, a Delaware limited liability company and an indirect wholly owned subsidiary of CenturyLink ("Merger Sub 2"), pursuant to which, subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, we will be acquired by CenturyLink in a cash and stock transaction, including the assumption of our debt (the "CenturyLink Merger"). See Note 2 - CenturyLink Merger. Principles of Consolidation and Basis of Presentation The consolidated financial statements include our and our subsidiaries' accounts in which we have a controlling interest. All significant intercompany accounts and transactions have been eliminated. The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP"). As part of our consolidation policy, we consider our controlled subsidiaries, investments in businesses in which we are not the primary beneficiary or do not have effective control but have the ability to significantly influence operating and financial policies, and variable interests resulting from economic arrangements that give us rights to economic risks or rewards of a legal entity. We do not have variable interests in a variable interest entity where we are required to consolidate the entity as the primary beneficiary. Due to exchange restrictions and other conditions, effective at the end of the third quarter of 2015 we deconsolidated our Venezuelan subsidiary and began accounting for our investment in our Venezuelan subsidiary using the cost method of accounting. The factors that led to our conclusions at the end of the third quarter of 2015 continued to exist through the end of the first quarter of 2017. The accompanying Consolidated Balance Sheet as of December 31, 2016, which was derived from audited Consolidated Financial Statements, and the unaudited interim Consolidated Financial Statements as of March 31, 2017 and for the three months ended March 31, 2017 and 2016 have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for quarterly reports on Form 10-Q and do not include all of the information and note disclosures required by GAAP for complete financial statements. These financial statements should be read in conjunction with our audited Consolidated Financial Statements and notes thereto included in our Form 10-K for the year ended December 31, 2016. In the opinion of our management, these financial statements contain all adjustments necessary for a fair presentation of financial position, results of operations and cash flows at the dates and for the interim periods presented herein. The results of operations for an interim period are not necessarily indicative of the results of operations expected for a full fiscal year. The preparation of the Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and the reported amounts of revenue and expenses during the reported period. Actual results could differ from these estimates under different assumptions or conditions and such differences could be material. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases ("ASC 842"), which requires entities that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. This ASU will replace most existing leasing guidance in U.S. GAAP when it becomes effective. The new standard is effective for fiscal years beginning after December 15, 2018, and interim periods within those years. Early application is permitted. The standard requires the use of a modified retrospective transition method. We are evaluating the effect that ASU 2016-02 will have on our Consolidated Financial Statements and related disclosures, and expect the new guidance to significantly increase the reported assets and liabilities on our Consolidated Balance Sheets. In May 2014, the Financial Accounting Standards Board issued ASU 2014-09, Revenue from Contracts with Customers, which amended the existing accounting standards for revenue recognition and requires an entity to recognize the amount of revenue it expects to be entitled to for the transfer of promised goods or services to customers. The ASU and subsequent amendments have been codified as ASC 606, Revenue from Contracts with Customers (“ASC 606”). In July 2015, the FASB deferred the effective date to annual reporting periods beginning after December 15, 2017, and interim reporting periods within those periods. Early adoption is permitted using the original effective date of annual reporting periods beginning after December 15, 2016, and interim reporting periods within those periods. The new guidance may be applied retrospectively to each prior period presented or prospectively with the cumulative effect recognized as of the date of initial adoption. We will not adopt ASC 606 early. We are performing a comprehensive analysis of our revenue streams and contractual arrangements to identify the effects of ASC 606 on our consolidated financial statements and are developing new accounting and reporting policies, business and internal control processes and procedures to facilitate adoption of the standard. Because we currently have service contracts that contain a significant financing component that are not currently separately accounted for, we will be required to estimate and record incremental revenue and interest cost associated with these contractual terms. In addition, we will be required to capitalize, and subsequently amortize, commission costs associated with obtaining or fulfilling our customer contracts, which we do not currently defer and amortize. We will also have to comply with new revenue disclosure requirements. We are continuing to review and evaluate underlying contract information that will be used to support new accounting and disclosure requirements under ASC 606 and evaluate other matters that may result from adoption of the standard. We have not yet selected a transition method, as our method of transition may be affected by the CenturyLink Merger, which we expect will be completed in the third quarter of 2017, and subsequent integration activities completed prior to the January 1, 2018 ASC 606 adoption date.

(1) Organization and Summary of Significant Accounting Policies

Description of Business

Level 3 Communications, Inc. and subsidiaries is a facilities-based provider (that is, a provider that owns or leases a substantial portion of the plant, property and equipment necessary to provide our services) of a broad range of integrated communications services. We created our communications network by constructing our own assets and through a combination of purchasing other companies and purchasing or leasing facilities from others. Our network is an international, facilities-based communications network. We designed our network to provide communications services that employ and take advantage of rapidly improving underlying optical, Internet Protocol, computing and storage technologies.

On October 31, 2016, we entered into an agreement and plan of merger (the "Merger Agreement") with CenturyLink, Inc., a Louisiana corporation ("CenturyLink"), Wildcat Merger Sub 1 LLC, a Delaware limited liability company and an indirect wholly owned subsidiary of CenturyLink ("Merger Sub 1"), and WWG Merger Sub LLC, a Delaware limited liability company and an indirect wholly owned subsidiary of CenturyLink ("Merger Sub 2"), pursuant to which, subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, we will be acquired by CenturyLink in a cash and stock transaction, including the assumption of our debt (the "CenturyLink Merger"). See Note 2 - CenturyLink Merger.

Principles of Consolidation and Basis of Presentation

The consolidated financial statements include our and our subsidiaries' accounts in which we have a controlling interest. All significant intercompany accounts and transactions have been eliminated. The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP").

As part of our consolidation policy, we consider our controlled subsidiaries, investments in businesses in which we are not the primary beneficiary or do not have effective control but have the ability to significantly influence operating and financial policies, and variable interests resulting from economic arrangements that give us rights to economic risks or rewards of a legal entity. We do not have variable interests in a variable interest entity where we are required to consolidate the entity as the primary beneficiary. Due to exchange restrictions and other conditions, effective at the end of the third quarter of 2015 we deconsolidated our Venezuelan subsidiary and began accounting for our investment in our Venezuelan subsidiary using the cost method of accounting. The factors that led to our conclusions at the end of the third quarter of 2015 continued to exist through the end of the first quarter of 2017.

The accompanying Consolidated Balance Sheet as of December 31, 2016, which was derived from audited Consolidated Financial Statements, and the unaudited interim Consolidated Financial Statements as of March 31, 2017 and for the three months ended March 31, 2017 and 2016 have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for quarterly reports on Form 10-Q and do not include all of the information and note disclosures required by GAAP for complete financial statements. These financial statements should be read in conjunction with our audited Consolidated Financial Statements and notes thereto included in our Form 10-K for the year ended December 31, 2016. In the opinion of our management, these financial statements contain all adjustments necessary for a fair presentation of financial position, results of operations and cash flows at the dates and for the interim periods presented herein. The results of operations for an interim period are not necessarily indicative of the results of operations expected for a full fiscal year.

The preparation of the Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and the reported amounts of revenue and expenses during the reported period. Actual results could differ from these estimates under different assumptions or conditions and such differences could be material.

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases ("ASC 842"), which requires entities that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. This ASU will replace most existing leasing guidance in U.S. GAAP when it becomes effective. The new standard is effective for fiscal years beginning after December 15, 2018, and interim periods within those years. Early application is permitted. The standard requires the use of a modified retrospective transition method. We are evaluating the effect that ASU 2016-02 will have on our Consolidated Financial Statements and related disclosures, and expect the new guidance to significantly increase the reported assets and liabilities on our Consolidated Balance Sheets.

In May 2014, the Financial Accounting Standards Board issued ASU 2014-09, Revenue from Contracts with Customers, which amended the existing accounting standards for revenue recognition and requires an entity to recognize the amount of revenue it expects to be entitled to for the transfer of promised goods or services to customers. The ASU and subsequent amendments have been codified as ASC 606, Revenue from Contracts with Customers (“ASC 606”). In July 2015, the FASB deferred the effective date to annual reporting periods beginning after December 15, 2017, and interim reporting periods within those periods. Early adoption is permitted using the original effective date of annual reporting periods beginning after December 15, 2016, and interim reporting periods within those periods. The new guidance may be applied retrospectively to each prior period presented or prospectively with the cumulative effect recognized as of the date of initial adoption. We will not adopt ASC 606 early.

We are performing a comprehensive analysis of our revenue streams and contractual arrangements to identify the effects of ASC 606 on our consolidated financial statements and are developing new accounting and reporting policies, business and internal control processes and procedures to facilitate adoption of the standard. Because we currently have service contracts that contain a significant financing component that are not currently separately accounted for, we will be required to estimate and record incremental revenue and interest cost associated with these contractual terms. In addition, we will be required to capitalize, and subsequently amortize, commission costs associated with obtaining or fulfilling our customer contracts, which we do not currently defer and amortize. We will also have to comply with new revenue disclosure requirements. We are continuing to review and evaluate underlying contract information that will be used to support new accounting and disclosure requirements under ASC 606 and evaluate other matters that may result from adoption of the standard. We have not yet selected a transition method, as our method of transition may be affected by the CenturyLink Merger, which we expect will be completed in the third quarter of 2017, and subsequent integration activities completed prior to the January 1, 2018 ASC 606 adoption date.