v3.8.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Feb. 15, 2018
Jun. 30, 2017
Document and Entity Information      
Entity Registrant Name Adamas Pharmaceuticals Inc    
Entity Central Index Key 0001328143    
Document Type 10-K    
Document Period End Date Dec. 31, 2017    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 301,001,186
Entity Common Stock, Shares Outstanding (in shares)   26,807,221  
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY