Fair Value Measurement (Unaudited) Other Financials (Details) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 5,128	[1]	$ 3,738	[1]
McMoRan Exploration Co. investment	482	[2]	500	[2]
Net embedded derivatives included in accounts receivable or payable	(402)	[1]	242	[1]
Trust assets (current and long-term)	153	[1],[3]	148	[1],[3]
Available-for-sale securities (current and long-term)	25	[1],[3]	34	[1],[3]
Derivative assets	0	[1],[4]	18	[1],[4]
Derivatives liabilities (current and long-term)	(55)	[1],[5]	(10)	[1],[5]
Long-term debt (including amounts due within one year)	(3,535)	[6]	(4,755)	[6]
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	5,128	[1]	3,738	[1]
McMoRan Exploration Co. investment	445	[2]	623	[2]
Net embedded derivatives included in accounts receivable or payable	(402)	[1]	242	[1]
Trust assets (current and long-term)	153	[1],[3]	148	[1],[3]
Available-for-sale securities (current and long-term)	25	[1],[3]	34	[1],[3]
Derivative assets	0	[1],[4]	18	[1],[4]
Derivatives liabilities (current and long-term)	(55)	[1],[5]	(10)	[1],[5]
Long-term debt (including amounts due within one year)	$ (3,830)	[6]	$ (5,146)	[6]

[1] Recorded at fair value.

[2] Recorded at cost and included in other assets. At December 31, 2010, fair value was based on a bid evaluation, which was an estimated price at which a dealer would pay for a security. At September 30, 2011, these securities were not actively trading; as such, fair value was based on a convertible pricing model using McMoRan Exploration Co.'s publicly traded common stock as the principle variable.

[3] Current portion included in other current assets and long-term portion included in other assets.

[4] Included in other current assets.

[5] Current portion included in accounts payable and accrued liabilities and long-term portion included in other liabilities.

[6] Recorded at cost except for long-term debt acquired in the Phelps Dodge acquisition, which was recorded at fair value at the acquisition date. Fair value of substantially all of FCX’s long-term debt is estimated based on quoted market prices.