Concentrations of Credit Risk (Details) (Revenue, Rights Granted [Member], Revenue from Rights Concentration Risk [Member])
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12 Months Ended | ||
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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Bristol-Myers Squibb [Member]
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Concentration Risk [Line Items] | |||
Concentration Risk, Percentage | 66.00% | 59.00% | 50.00% |
Merck [Member]
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Concentration Risk [Line Items] | |||
Concentration Risk, Percentage | 22.00% | 0.00% | 0.00% |
Daiichi Sankyo [Member]
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Concentration Risk [Line Items] | |||
Concentration Risk, Percentage | 12.00% | 0.00% | 3.00% |
Sanofi [Member]
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Concentration Risk [Line Items] | |||
Concentration Risk, Percentage | 0.00% | 39.00% | 42.00% |