Quarterly report pursuant to Section 13 or 15(d)


Cover - shares
9 Months Ended
Sep. 30, 2021
Nov. 05, 2021
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2021  
Document Transition Report false  
Entity File Number 001-33093  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 77-0160744  
Entity Address, Address Line One 5980 Horton Street, Suite 405  
Entity Address, City or Town Emeryville  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94608  
City Area Code 858  
Local Phone Number 550-7500  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol LGND  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   16,711,641
Amendment Flag false  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q3  
Entity Central Index Key 0000886163  
Current Fiscal Year End Date --12-31