Quarterly report pursuant to Section 13 or 15(d)

Financing Arrangements (Notes Payable) (Details)

v2.4.1.9
Financing Arrangements (Notes Payable) (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Notes Payable, Current and Noncurrent [Abstract]    
Net carrying amount $ 198,219,000us-gaap_ConvertibleDebtNoncurrent $ 195,908,000us-gaap_ConvertibleDebtNoncurrent
Current notes payable 348,000us-gaap_NotesPayableCurrent 334,000us-gaap_NotesPayableCurrent
Total notes payable 198,567,000us-gaap_NotesPayable 196,242,000us-gaap_NotesPayable
2019 convertible senior notes    
Notes Payable, Current and Noncurrent [Abstract]    
Principal amount outstanding 245,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= lgnd_A2019ConvertibleSeniorNotesMember
245,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= lgnd_A2019ConvertibleSeniorNotesMember
Unamortized discount (46,781,000)us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= lgnd_A2019ConvertibleSeniorNotesMember
(49,092,000)us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= lgnd_A2019ConvertibleSeniorNotesMember
Net carrying amount 198,219,000us-gaap_ConvertibleDebtNoncurrent
/ us-gaap_DebtInstrumentAxis
= lgnd_A2019ConvertibleSeniorNotesMember
195,908,000us-gaap_ConvertibleDebtNoncurrent
/ us-gaap_DebtInstrumentAxis
= lgnd_A2019ConvertibleSeniorNotesMember
Convertible notes payable, Viking Therapeutics, Inc.    
Notes Payable, Current and Noncurrent [Abstract]    
Current notes payable $ 348,000us-gaap_NotesPayableCurrent
/ us-gaap_DebtInstrumentAxis
= us-gaap_ConvertibleNotesPayableMember
$ 334,000us-gaap_NotesPayableCurrent
/ us-gaap_DebtInstrumentAxis
= us-gaap_ConvertibleNotesPayableMember