Nature of Operations and Basis of Presentation - Additional Information (Details)		3 Months Ended
	Sep. 19, 2017	Mar. 31, 2018 Patient
Organization Consolidation and Presentation of Financial Statement [Line Items]
Number of patients impacted		7,000
Merger of Private Acer with Opexa Merger Sub Incorporation
Organization Consolidation and Presentation of Financial Statement [Line Items]
Business combination date of completion	Sep. 19, 2017
Business combination date of agreement	Jun. 30, 2017
Reverse stock split ratio	0.09656678989