v3.19.1
Document and Entity Information - $ / shares
3 Months Ended
Mar. 31, 2019
May 06, 2019
Document and Entity Information [Abstract]    
Entity Registrant Name Blueprint Medicines Corp  
Entity Central Index Key 0001597264  
Document Type 10-Q  
Document Period End Date Mar. 31, 2019  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Listing, Par Value Per Share $ 0.001  
Trading Symbol BPMC  
Entity Current Reporting Status Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   48,853,933
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1