Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Acquisition of CyDex) (Details)

v2.4.1.9
Fair Value Measurements (Acquisition of CyDex) (Details) (Cydex Pharmaceuticals, Inc, USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Credit Derivatives [Line Items]    
Amount Of Revenue For Contingent Consideration 15lgnd_AmountOfRevenueForContingentConsideration  
Contingent Consideration Classified as Equity
   
Credit Derivatives [Line Items]    
Revenue volatility 25.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
25.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
Average of probability of commercialization 77.00%lgnd_FairValueInputsAverageOfProbabilityOfCommercialization
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
81.00%lgnd_FairValueInputsAverageOfProbabilityOfCommercialization
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
Sales beta 0.70lgnd_FairValueInputsSalesBeta
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
0.60lgnd_FairValueInputsSalesBeta
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
Credit rating B B
Equity risk premium 6.00%us-gaap_FairValueInputsControlPremium
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
6.00%us-gaap_FairValueInputsControlPremium
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
Minimum | Contingent Consideration Classified as Equity    
Credit Derivatives [Line Items]    
Range of annual revenue subject to revenue sharing 17.7lgnd_FairValueInputsAnnualRevenueSubjectToRevenueSharing
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
17.2lgnd_FairValueInputsAnnualRevenueSubjectToRevenueSharing
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Maximum | Contingent Consideration Classified as Equity    
Credit Derivatives [Line Items]    
Range of annual revenue subject to revenue sharing 21.6lgnd_FairValueInputsAnnualRevenueSubjectToRevenueSharing
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
17.3lgnd_FairValueInputsAnnualRevenueSubjectToRevenueSharing
/ us-gaap_BusinessAcquisitionAxis
= lgnd_CydexPharmaceuticalsIncMember
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_ContingentConsiderationClassifiedAsEquityMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember