Document and Entity Information - shares
9 Months Ended
Sep. 30, 2018
Nov. 01, 2018
Document And Entity Information [Abstract]    
Entity Registrant Name Albireo Pharma, Inc.  
Entity Central Index Key 0001322505  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Entity Current Reporting Status Yes  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Trading Symbol albo  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   11,969,928