Exercise price of the warrants.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The estimated amount of dividends to be paid to holders of the underlying shares (expected dividends) over the option's term. Dividends are taken into account because payment of dividends to shareholders reduces the fair value of the underlying shares, and option holders generally do not receive dividends.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Stock-Based Compensation - Additional Information (Detail) (USD $)	1 Months Ended			9 Months Ended
	Feb. 11, 2013	Jan. 23, 2013	Jan. 29, 2013	Sep. 30, 2013	Jan. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, common stock shares issued and outstanding				1,094,854		824,620
Option expense recognized				$ 705,408
Unamortized stock compensation expense				970,912
Number of Shares, Granted				342,572
Expected dividends				0
Number of Shares, Forfeited and canceled				72,338
Warrant term	4 years	5 years	5 years
Warrants issued to purchase common stock		243,750	187,500		243,750
Warrant exercise price	$ 3.00	$ 1.24	$ 1.21
Warrant redemption price per share		$ 0.01	$ 0.01
Terms for warrant redeem		Opexa 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 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.
Number of common stock to be issued upon exercise of warrant	541,668		187,500
Warrants Attached to Debt
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount rate		0.76%
Expected life		5 years
Expected volatility rate		191.00%
Expected dividends		0
Estimated fair value of warrants		195,969
Warrants, Forfeited and canceled				1,482,892
Common Stock Warrants issued to Release a Claim on Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount rate			0.90%
Expected life			5 years
Expected volatility rate			191.00%
Estimated fair value of warrants			219,553
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, term				10 years
Employee Stock Option \| Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, term				10 years
Number of Shares, Granted				125,000
Weighted average exercise price, Granted				$ 2.34
Vesting period				3 years
Fair value of stock granted during period				285,226
Discount rate				1.87%
Expected life				5 years 3 months
Expected volatility rate				194.00%
Expected dividends				0
Employee Stock Option \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, term				10 years
Number of Shares, Granted				129,000
Vesting period				3 years
Fair value of stock granted during period				218,348
Expected life				5 years 3 months
Expected dividends				$ 0
Employee Stock Option \| Employees \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price, Granted				$ 1.45
Discount rate				1.73%
Expected volatility rate				201.00%
Employee Stock Option \| Employees \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price, Granted				$ 1.75
Discount rate				2.78%
Expected volatility rate				204.00%
Non Employee Director Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, term				10 years
Number of Shares, Granted				88,572
Weighted average exercise price, Granted				$ 1.75
Discount rate				1.73%
Expected life				5 years 3 months
Expected volatility rate				201.00%
Fair value stock granted during period				$ 151,867
Stock options vesting percentage, immediately from date of grant				50.00%
Stock options vesting percentage, remaining of period				50.00%
Non Employee Director Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				8 months
Non Employee Director Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				1 year
2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation, common stock shares authorized				625,000
Share based compensation, common stock shares issued and outstanding				1,094,854