Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Mar. 27, 2019
Oct. 22, 2018
Document and Entity Information [Abstract]      
Entity Registrant Name Osmotica Pharmaceuticals plc    
Entity Central Index Key 0001739426    
Document Type 10-K    
Document Period End Date Dec. 31, 2018    
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 Non-accelerated Filer    
Entity Shell Company false    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period true    
Entity Public Float     $ 75.1
Entity Common Stock, Shares Outstanding   52,518,924  
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY