v3.26.1
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Jul. 31, 2026
Cover Abstract    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Securities Act File Number 001-38905  
Entity Registrant Name NextCure, Inc.  
Entity Central Index Key 0001661059  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 47-5231247  
Entity Address, Address Line One 8000 Virginia Manor Road  
Entity Address, Address Line Two Suite 140  
Entity Address, City or Town Beltsville  
Entity Address, State or Province MD  
Entity Address, Postal Zip Code 20705  
City Area Code 240  
Local Phone Number 399-4900  
Title of 12(b) Security Common Stock, $0.001 par value per share  
Trading Symbol NXTC  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   4,577,359
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false