Quarterly report pursuant to Section 13 or 15(d)

Cover Page

Cover Page - shares
6 Months Ended
Jun. 30, 2020
Aug. 04, 2020
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2020  
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 3911 Sorrento Valley Boulevard, Suite 110  
Entity Address, City or Town San Diego  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92121  
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   16,078,143
Amendment Flag false  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0000886163  
Current Fiscal Year End Date --12-31