Supplement Fact (Details)	12 Months Ended
Dec. 31, 2011 lawsuits	Dec. 31, 2010 lawsuits	Dec. 31, 2009 lawsuits	Dec. 31, 2008 lawsuits	Dec. 31, 2006 lawsuits
Loss Contingencies [Line Items]
Number of Shareholder Derivative Lawsuits Filed					3
New shareholder derivative lawsuits filed	1	1			4
Derivative lawsuits pending	1
Loss Contingency, Claims Settled and Dismissed, Number	2		1	4	1

Number of Shareholder Derivative Lawsuits Filed

No definition available.

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- Details

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- Definition

The number of claims settled and dismissed during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

+ Details

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- Definition

The total amount of pending claims pertaining to a loss contingency accrual as of the balance sheet date.

+ References

+ Details

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