v3.8.0.1
Document and Entity Information
12 Months Ended
Dec. 31, 2017
Document And Entity Information [Abstract]  
Document Type S-1
Amendment Flag false
Document Period End Date Dec. 31, 2017
Trading Symbol GTHX
Entity Registrant Name G1 THERAPEUTICS, INC.
Entity Central Index Key 0001560241
Entity Filer Category Non-accelerated Filer