Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation (Goodwill and Other Identifiable Intangible Assets) (Details)

v2.4.1.9
Basis of Presentation (Goodwill and Other Identifiable Intangible Assets) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Summary of Goodwill and Other Identifiable Intangible Assets    
Goodwill $ 12,238us-gaap_Goodwill $ 12,238us-gaap_Goodwill
Total goodwill and other identifiable intangible assets, net 62,367us-gaap_IntangibleAssetsNetIncludingGoodwill 62,961us-gaap_IntangibleAssetsNetIncludingGoodwill
Complete technology    
Summary of Goodwill and Other Identifiable Intangible Assets    
Definite lived intangible assets 15,267us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_PatentedTechnologyMember
15,267us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_PatentedTechnologyMember
Less: Accumulated amortization (3,189)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_PatentedTechnologyMember
(2,999)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_PatentedTechnologyMember
Trade name    
Summary of Goodwill and Other Identifiable Intangible Assets    
Definite lived intangible assets 2,642us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeNamesMember
2,642us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeNamesMember
Less: Accumulated amortization (553)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeNamesMember
(519)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_TradeNamesMember
Customer relationships    
Summary of Goodwill and Other Identifiable Intangible Assets    
Definite lived intangible assets 29,600us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
29,600us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
Less: Accumulated amortization (6,194)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
(5,824)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
Acquired in-process research and development    
Summary of Goodwill and Other Identifiable Intangible Assets    
Acquired in-process research and development $ 12,556us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= lgnd_AcquiredInProcessResearchAndDevelopmentMember
$ 12,556us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
/ us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis
= lgnd_AcquiredInProcessResearchAndDevelopmentMember