Date of reincorporation.

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- Definition

Organization, consolidation and presentation of financial statement.

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No definition available.

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- Definition

Date when the business acquisition agreement was executed, in CCYY-MM-DD format.

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No definition available.

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With respect to a business combination completed during the period, this element provides a description of the business, other than the name, which may include the industry, size, products and other important information.

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Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Face amount or stated value per share of common stock.

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Face amount per share of no-par value preferred stock nonredeemable or redeemable solely at the option of the issuer.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The expected number of positions to be eliminated as a result of restructuring activities.

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No definition available.

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The number of positions eliminated during the period as a percentage of total positions eliminated during the period in connection with the restructuring plan(s).

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No definition available.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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Nature of Operations and Basis of Presentation - Additional Information (Details)			9 Months Ended
	Jun. 28, 2019 Employee	Sep. 19, 2017	Sep. 30, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares	May 15, 2018 $ / shares	May 14, 2018 $ / shares
Organization Consolidation and Presentation of Financial Statement [Line Items]
Cash and cash equivalents \| $			$ 16,121,903	$ 41,671,284
Corporate restructuring, reduction of full-time workforce percentage	60.00%
Corporate restructuring, reduction of full-time workforce employees \| Employee	48
Preferred stock, no par value						$ 0
Preferred stock, par value			$ 0.0001	$ 0.0001
Common stock, par value			$ 0.0001	$ 0.0001		$ 0.01
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
Delaware Reincorporation and Subsidiary Merger
Organization Consolidation and Presentation of Financial Statement [Line Items]
Merger incorporation description			On May 15, 2018, the Company changed its state of incorporation from the State of Texas to the State of Delaware pursuant to a plan of conversion, dated May 15, 2018. As a result of this reincorporation, the par value of the Company’s preferred stock was changed to $0.0001 from no par value and the par value of the Company’s common stock was reduced to $0.0001 from $0.01. Immediately following the Reincorporation, the holding company structure was eliminated by merging wholly-owned subsidiary Private Acer with and into the Company (the “Subsidiary Merger”). The Company was the surviving corporation in connection with the Subsidiary Merger.
Date of reincorporation			May 15, 2018
Preferred stock, par value					$ 0.0001
Common stock, par value					$ 0.0001