Annual report pursuant to Section 13 and 15(d)


Cover - USD ($)
$ in Billions
12 Months Ended
Dec. 31, 2021
Feb. 23, 2022
Jun. 30, 2021
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 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 $.001 per share    
Trading Symbol LGND    
Security Exchange Name NASDAQ    
Entity Well-Known Seasoned Issuer Yes    
Entity Voluntary Filers No    
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    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 1.8
Entity Common Stock, Shares Outstanding   16,852,650  
Documents Incorporated by Reference Portions of the Proxy Statement for the Registrant’s 2021 Annual Meeting of Stockholders to be filed with the Commission within 120 days of December 31, 2021 are incorporated by reference in Part III of this Annual Report on Form 10-K. With the exception of those portions that are specifically incorporated by reference in this Annual Report on Form 10-K, such Proxy Statement shall not be deemed filed as part of this Report or incorporated by reference herein.    
Amendment Flag false    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Entity Central Index Key 0000886163    
Current Fiscal Year End Date --12-31