Document And Entity Information - shares
9 Months Ended
Sep. 30, 2019
Nov. 07, 2019
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Trading Symbol ALDX  
Entity Registrant Name ALDEYRA THERAPEUTICS, INC.  
Entity Central Index Key 0001341235  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Emerging Growth Company true  
Entity Small Business true  
Entity Ex Transition Period false  
Entity Common Stock, Shares Outstanding   27,952,937
Entity Current Reporting Status Yes  
Entity Shell Company false  
Title of 12(b) Security Common Stock, $0.001 par value per share  
Security Exchange Name NASDAQ  
Entity Interactive Data Current Yes  
Entity File Number 001-36332  
Entity Tax Identification Number 20-1968197  
Entity Address, Address Line One 131 Hartwell Avenue  
Entity Address, Address Line Two Suite 320  
Entity Address, City or Town Lexington  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 02421  
City Area Code (781)  
Local Phone Number 761-4904  
Document Quarterly Report true  
Document Transition Report false  
Entity Incorporation, State or Country Code DE