Basis of Presentation (Policy)

6 Months Ended

Jun. 30, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities (the “Company”). The Company’s primary business is the production of thermal and metallurgical coal from surface and underground mines located throughout the United States, for sale to utility, industrial and steel producers both in the United States and around the world. The Company currently operates mining complexes in West Virginia, Kentucky, Maryland, Virginia, Illinois, Wyoming, Colorado and Utah. In addition,the Company has a metallurgical coal mine in development in West Virginia. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation.

The Company has entered into an agreement to sell a subsidiary which operates three mining complexes in the Western Bituminous reportable segment ("WBIT"). The results of these mining complexes have been segregated from continuing operations and are reflected, net of tax, as discontinued operations in the condensed consolidating statements of operations for all periods presented. See further discussion in Note 3, "Discontinued Operations".

On June 21, 2012, the Company announced the closing of four mining complexes and the temporary idling of a fifth complex, which resulted in closure costs and impairment charges of $525.6 million, which are reflected on the line "Asset impairment and mine closures costs" on the condensed consolidated statements of operations.

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and six month periods ended June 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2012 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.