General	9 Months Ended
Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General Organization We are a Delaware limited liability company, originally formed in 1927 as a corporation. We are an interstate pipeline system serving the Rocky Mountain Region. Unless the context otherwise requires, references to "us," we," "our," or "CIG," are describing Colorado Interstate Gas Company, L.L.C. and its consolidated subsidiaries. We are wholly owned by El Paso Pipeline Partners Operating Company, L.L.C., a wholly owned subsidiary of El Paso Pipeline Partners, L.P. (EPB), a master limited partnership indirectly controlled by Kinder Morgan, Inc. (KMI). On May 24, 2012, EPB acquired the remaining 14% interest in us from a wholly owned subsidiary of El Paso LLC (El Paso), and we became an indirect wholly owned subsidiary of EPB. Basis of Presentation We have prepared our accompanying unaudited consolidated financial statements under the rules and regulations of the United States Securities and Exchange Commission (SEC). These rules and regulations conform to the accounting principles contained in the Financial Accounting Standards Board's Accounting Standards Codification, the single source of Generally Accepted Accounting Principles in the United States of America (GAAP) and referred to in this report as the Codification. Under such rules and regulations, we have condensed or omitted certain information and notes normally included in financial statements prepared in conformity with the Codification. We believe, however, that our disclosures are adequate to make the information presented not misleading. Our accompanying consolidated financial statements reflect normal adjustments, and also recurring adjustments that are, in the opinion of our management, necessary for a fair presentation of our financial results for the interim periods. Certain amounts from prior periods have been reclassified to conform to the current presentation. Interim results are not necessarily indicative of results for a full year; accordingly, you should read these consolidated financial statements in conjunction with our consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2012, which we refer to in this report as our 2012 Form 10-K. Immaterial Correction During the second quarter of 2012, we determined that certain accrued environmental liabilities established in periods prior to 2008 were overstated by approximately $6 million. We corrected this error in June 2012 by reducing accrued liabilities with an offsetting reduction in operating expenses. We evaluated the impact of the error and determined that it was not material to our previously reported consolidated financial statements. Additionally, we determined that the correction of the error was not material to our 2012 consolidated financial statements.

General

9 Months Ended

Sep. 30, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

We are a Delaware limited liability company, originally formed in 1927 as a corporation. We are an interstate pipeline system serving the Rocky Mountain Region. Unless the context otherwise requires, references to "us," we," "our," or "CIG," are describing Colorado Interstate Gas Company, L.L.C. and its consolidated subsidiaries. We are wholly owned by El Paso Pipeline Partners Operating Company, L.L.C., a wholly owned subsidiary of El Paso Pipeline Partners, L.P. (EPB), a master limited partnership indirectly controlled by Kinder Morgan, Inc. (KMI). On May 24, 2012, EPB acquired the remaining 14% interest in us from a wholly owned subsidiary of El Paso LLC (El Paso), and we became an indirect wholly owned subsidiary of EPB.

Basis of Presentation

We have prepared our accompanying unaudited consolidated financial statements under the rules and regulations of the United States Securities and Exchange Commission (SEC). These rules and regulations conform to the accounting principles contained in the Financial Accounting Standards Board's Accounting Standards Codification, the single source of Generally Accepted Accounting Principles in the United States of America (GAAP) and referred to in this report as the Codification. Under such rules and regulations, we have condensed or omitted certain information and notes normally included in financial statements prepared in conformity with the Codification. We believe, however, that our disclosures are adequate to make the information presented not misleading.

Our accompanying consolidated financial statements reflect normal adjustments, and also recurring adjustments that are, in the opinion of our management, necessary for a fair presentation of our financial results for the interim periods. Certain amounts from prior periods have been reclassified to conform to the current presentation. Interim results are not necessarily indicative of results for a full year; accordingly, you should read these consolidated financial statements in conjunction with our consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2012, which we refer to in this report as our 2012 Form 10-K.

Immaterial Correction

During the second quarter of 2012, we determined that certain accrued environmental liabilities established in periods prior to 2008 were overstated by approximately $6 million. We corrected this error in June 2012 by reducing accrued liabilities with an offsetting reduction in operating expenses.

We evaluated the impact of the error and determined that it was not material to our previously reported consolidated financial statements. Additionally, we determined that the correction of the error was not material to our 2012 consolidated financial statements.