v3.26.3
Stockholders' Equity - Narrative (Details) - USD ($)
 1 Months Ended 9 Months Ended
Jun. 30, 2026
Aug. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Feb. 27, 2026
Apr. 30, 2023
Class of Stock [Line Items]            
Outstanding options that are exercisable (in shares)     1,200,000      
Outstanding options that are exercisable, weighted average exercise price (in USD per share)     $ 83.58      
Employee Stock Purchase Plan            
Repurchase of common stock     $ 60,000,000 $ 15,000,000    
Common Stock            
Employee Stock Purchase Plan            
Repurchase of common stock $ 60,000,000.0 $ 15,000,000.0        
Stock repurchased during period (in shares) 228,859 102,034        
Shares acquired, average cost per share $ 262.17 $ 147.01        
April 2023 Repurchase Agreement            
Employee Stock Purchase Plan            
Authorized stock repurchase amount           $ 50,000,000.0
At-the Market Equity Offering            
Employee Stock Purchase Plan            
Sale of stock, authorized offering amount         $ 100,000,000.0  
Ligand Pharmaceuticals Incorporated 2002 Stock Incentive Plan            
Class of Stock [Line Items]            
Number of shares of common stock available (in shares) 600,000          
Amended ESPP            
Employee Stock Purchase Plan            
Share purchase price as percent of market price (as a percent)     85.00%      
Shares available for future purchases (in shares)     17,424