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3/31/2011
USD ($)
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12/31/2010
USD ($)
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3/31/2011
USD ($)
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12/31/2010
USD ($)
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a
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