Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2012
Disclosure Text Block [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies General Anadarko Petroleum Corporation is engaged in the exploration, development, production, and marketing of natural gas, crude oil, condensate, and natural gas liquids (NGLs). In addition, the Company engages in the gathering, processing, treating, and transporting of natural gas, crude oil, and NGLs. The Company also participates in the hard minerals business through its ownership of non-operated joint ventures and royalty arrangements. Unless the context otherwise requires, the terms “Anadarko” and “Company” refer to Anadarko Petroleum Corporation and its consolidated subsidiaries. Basis of Presentation The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for the fair presentation of the Company's Consolidated Balance Sheets as of September 30, 2012, and December 31, 2011, the Consolidated Statements of Income and Comprehensive Income for the three and nine months ended September 30, 2012 and 2011, the Consolidated Statements of Cash Flows for the nine months ended September 30, 2012 and 2011, and the Consolidated Statement of Equity for the nine months ended September 30, 2012. Certain prior-period amounts have been reclassified to conform to the current-period presentation. Use of Estimates In preparing financial statements in accordance with accounting principles generally accepted in the United States, management makes informed judgments and estimates that affect the reported amounts of assets, liabilities, revenues, and expenses. Management evaluates its estimates and related assumptions regularly, including those related to the value of properties and equipment; proved reserves; goodwill; intangible assets; asset retirement obligations; litigation reserves; environmental liabilities; pension assets, liabilities, and costs; income taxes; and fair values. Changes in facts and circumstances or additional information may result in revised estimates, and actual results may differ from these estimates.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2012

Summary of Significant Accounting Policies

1. Summary of Significant Accounting Policies

General Anadarko Petroleum Corporation is engaged in the exploration, development, production, and marketing of natural gas, crude oil, condensate, and natural gas liquids (NGLs). In addition, the Company engages in the gathering, processing, treating, and transporting of natural gas, crude oil, and NGLs. The Company also participates in the hard minerals business through its ownership of non-operated joint ventures and royalty arrangements. Unless the context otherwise requires, the terms “Anadarko” and “Company” refer to Anadarko Petroleum Corporation and its consolidated subsidiaries.

Basis of Presentation The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for the fair presentation of the Company's Consolidated Balance Sheets as of September 30, 2012, and December 31, 2011, the Consolidated Statements of Income and Comprehensive Income for the three and nine months ended September 30, 2012 and 2011, the Consolidated Statements of Cash Flows for the nine months ended September 30, 2012 and 2011, and the Consolidated Statement of Equity for the nine months ended September 30, 2012. Certain prior-period amounts have been reclassified to conform to the current-period presentation.

Use of Estimates In preparing financial statements in accordance with accounting principles generally accepted in the United States, management makes informed judgments and estimates that affect the reported amounts of assets, liabilities, revenues, and expenses. Management evaluates its estimates and related assumptions regularly, including those related to the value of properties and equipment; proved reserves; goodwill; intangible assets; asset retirement obligations; litigation reserves; environmental liabilities; pension assets, liabilities, and costs; income taxes; and fair values. Changes in facts and circumstances or additional information may result in revised estimates, and actual results may differ from these estimates.