Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation (Fair Value Valuation Assumptions) (Details)

v2.4.1.9
Basis of Presentation (Fair Value Valuation Assumptions) (Details)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Summary of fair-value options awarded to employees and directors    
Risk-free interest rate 1.80%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum 1.90%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum
Dividend yield 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Expected volatility 58.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum 69.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum
Expected term 6 years 7 months 6 days 6 years 4 months 24 days
Forfeiture rate 8.50%lgnd_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueForfeitureRate 9.70%lgnd_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueForfeitureRate