Subsequent Events - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended		119 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended						1 Months Ended
	Jul. 25, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Nov. 30, 2012	Nov. 30, 2012 $1.5 Million Purchase Agreement with Lincoln Park	Dec. 31, 2012 $1.5 Million Purchase Agreement with Lincoln Park	Jan. 23, 2013 Subsequent Event	Jan. 29, 2013 Subsequent Event	Jan. 28, 2013 Subsequent Event	Jan. 23, 2013 Subsequent Event Maximum	Feb. 28, 2013 Subsequent Event Option and License Agreement	Jan. 31, 2013 Subsequent Event $1.5 Million Purchase Agreement with Lincoln Park	Jan. 31, 2013 Subsequent Event $1.5 Million Purchase Agreement with Lincoln Park Issuance of Equity	Feb. 28, 2013 Convertible debt	Feb. 26, 2013 Convertible debt	Jan. 23, 2013 Convertible debt	Feb. 28, 2013 Convertible debt Common Stock	Jan. 23, 2013 Convertible debt Related Party	Feb. 11, 2013 Private Registered Offering	Feb. 28, 2013 ATM Agreement	Feb. 28, 2013 ATM Agreement Maximum
Subsequent Event [Line Items]
Common shares issued						56,507	265,000							125,000		77,034		288,229			167,618
Purchase agreement, aggregate shares opexa has right to sell		$ 16,500,000		$ 16,500,000	$ 16,500,000		$ 1,500,000						$ 1,500,000
Net proceeds from shares sold														142,400							536,417
Common stock issued as fee							2,610							975
Gross proceed from sale of common stock																	650,000		100,000
Debt Instrument, Maturity Date	Jul. 25, 2014																Jan. 23, 2014
Convertible debt instrument, effective interest rate	12.00%																12.00%
Convertible debt, conversion price	$ 100.00																$ 1.30
Minimum receipt of proceeds from sale of equity securities and/or as payments from partners to pay any remaining balance of note payable																	7,500,000
Number of business days to pay remaining convertible debts																	5 days
Payments for principal and interest			35,607	311,222												567,368
Warrant exercise price	$ 5.00							$ 1.24	$ 1.21											$ 3.00
Warrant term	5 years							5 years	5 years											4 years
Number of common stock to be issued upon exercise of warrant	1,436,121								187,500		243,750
Warrant redemption price per share								$ 0.01	$ 0.01
Terms for warrant redeem	Opexa can redeem the warrants at $0.01 per share if its common stock closes at or above $10.00 per share for 20 consecutive trading days.							The Company can redeem the warrants at $0.01 per share if the Company’s common stock closes at or above $10.00 per share for 20 consecutive trading days.	The Company can redeem the warrants at $0.01 per underlying share of common stock if the common stock closes at or above $10.00 per share for 20 consecutive trading days.
Restricted cash		1,000,000		1,000,000					500,000	500,000
Convertible notes, principal amount converted															900,000
common stock to be sold																						1,000,000
Commission rate on gross proceed for common stock sold																				6.00%	3.00%
Agent commission and fees																					16,105
Option and License Agreement, upfront payment received												5,000,000
Common shares issued																				1,083,334
Warrants settlement ratio																				Each unit consisting of one share of common stock and a warrant to purchase half (0.5) a share of common stock
Share issue to private offering, price per share																				$ 3.00
Proceeds from issuance of common stocks and warrants, net		$ 381,309	$ 8,618,157	$ 49,453,797			$ 333,970													$ 3,250,002