Other Current Assets - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Advance payments to vendors and consultants	$ 453,800	$ 21,982
Deferred financing cost	151,985	134,518
Other Long-term Assets
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Deferred financing cost	63,013	63,013
$1.5 Million Purchase Agreement with Lincoln Park
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Purchase agreement, aggregate shares opexa has right to sell	1,500,000	1,500,000
Purchase Agreements | Other Current Assets
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Deferred financing cost	134,518	134,518
Purchase Agreements | $1.5 Million Purchase Agreement with Lincoln Park
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Purchase agreement, aggregate shares opexa has right to sell	1,500,000
Merck Agreement | Other Current Assets
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Deferred financing cost	44,069	44,069
Merck Agreement | Other Long-term Assets
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Deferred financing cost	63,013	63,013
ATM Agreement | Third Party
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Deferred financing cost	$ 17,467