Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Aug. 01, 2019
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0001061027  
Entity Current Reporting Status Yes  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   111,320,000
Entity Shell Company false  
Entity Small Business true  
Entity Emerging Growth Company false  
Trading Symbol SNSS  
Entity File Number 000-51531  
Entity Tax Identification Number 943295878  
Entity Address, Address Line One 395 Oyster Point Boulevard  
Entity Address, Address Line Two Suite 400  
Entity Address, City or Town South San Francisco  
Entity Address, State or Province California  
Entity Address, Postal Zip Code 94080  
City Area Code (650)  
Local Phone Number 266-3500