XML 88 R1.htm IDEA: XBRL DOCUMENT v3.20.1
Document And Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Mar. 18, 2020
Jun. 28, 2019
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Entity Registrant Name GOSSAMER BIO, INC.    
Trading Symbol GOSS    
Entity Central Index Key 0001728117    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company true    
Entity Ex Transition Period true    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Shell Company false    
Entity Public Float     $ 947.8
Entity Common Stock, Shares Outstanding   66,336,562  
Title of 12(b) Security Common Stock, $0.0001 par value per share    
Security Exchange Name NASDAQ    
Entity File Number 001-38796    
Entity Tax Identification Number 47-5461709    
Entity Address, Address Line One 3013 Science Park Road    
Entity Address, City or Town San Diego    
Entity Address, State or Province CA    
Entity Incorporation, State or Country Code DE    
Entity Address, Postal Zip Code 92121    
City Area Code 858    
Local Phone Number 684-1300    
Document Annual Report true    
Document Transition Report false    
Documents Incorporated by Reference

Certain sections of the registrant’s definitive proxy statement for the 2020 annual meeting of stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after end of this fiscal year covered by this Form 10-K are incorporated by reference into Part III of this Form 10-K.