Consolidated Statement of Stockholders' Equity (Unaudited) (Parenthetical) (USD $)	6 Months Ended
Jun. 30, 2011
Consolidated Statement of Stockholders' Equity [Abstract]
Mandatory convertible preferred stock price per share	$ 100.00

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mcp_MandatoryConvertiblePreferredStockPricePerShare

Namespace Prefix:

mcp

Data Type:

num:perShareItemType

Balance Type:

na

Period Type:

duration