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Eligible employee threshold percentage.

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Number of stock incentive plans.

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Preferred Stock Accretion at Annualized Rate

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Share based compensation arrangement by share based payment award exercise price condition.

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Share based compensation arrangement by share based payment award maximum amount payable in cash per employee.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Exercise price per share or per unit of warrants or rights outstanding.

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Number of warrants or rights outstanding.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Price of the entity's common stock which would be required to be attained for the conversion feature embedded in the debt instrument to become effective.

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Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

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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 maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Date the equity-based award expires, in CCYY-MM-DD format.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The highest quantity of shares an employee can purchase under the plan per period.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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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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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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Purchase price of common stock expressed as a percentage of its fair value.

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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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Description of the reverse stock split arrangement. Also provide the retroactive effect given by the reverse split that occurs after the balance sheet date but before the release of financial statements.

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Stockholders' Equity (Deficit) - Additional Information (Detail)			3 Months Ended		6 Months Ended
	Feb. 09, 2016	Jun. 09, 2015 USD ($) shares	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares	Jun. 30, 2018 USD ($) d Incentive_Plan $ / shares shares	Jun. 30, 2017 USD ($)	Dec. 31, 2017 $ / shares shares	Feb. 19, 2016 shares	Feb. 18, 2016 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reverse stock split ratio					1-for-12
Reverse stock split, conversion ratio	0.50000	0.16666			0.08333
Common stock shares authorized			75,000,000		75,000,000		75,000,000	75,000,000	150,000,000
Common stock, par value \| $ / shares			$ 0.0001		$ 0.0001		$ 0.0001
Preferred stock, par value \| $ / shares			$ 0.0001		$ 0.0001		$ 0.0001
Preferred stock, shares authorized			24,984,166		24,984,166		24,984,166
Number of warrants			120,000		120,000
Warrants, exercise price \| $ / shares			$ 3.52		$ 3.52
Warrants, expiration date					Oct. 01, 2021
Number of stock incentive plans \| Incentive_Plan					2
Stock incentive plan expiration date					Aug. 31, 2015
Share-based compensation \| $			$ 103,904	$ 207,808	$ 207,808	$ 416,993
Weighted average fair value of options granted \| $ / shares			$ 0	$ 0
2015 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for stock-based compensation		450,000
Series AA-2 Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, par value \| $ / shares			$ 0.0001		$ 0.0001
Preferred stock, shares authorized			7,223,145		7,223,145
Series AA-2 Convertible Preferred Stock [Member] \| Penelope Mining LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of trading days \| d					20
Series AA-1 Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, par value \| $ / shares			$ 0.0001		$ 0.0001
Preferred stock, shares authorized			8,427,004		8,427,004
Preferred stock Liquidation preference accretion rate					8.00%
Minimum [Member] \| Series AA-2 Convertible Preferred Stock [Member] \| Penelope Mining LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of common stock \| $ / shares					$ 15.12
Board Of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reverse stock split ratio					1-for-2
Stockholders [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reverse stock split ratio					1-for-6
Incentive Stock Options [Member] \| 2015 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for stock-based compensation		450,000
Additional shares authorized for stock-based compensation					200,000
Common Stock [Member] \| Incentive Stock Options [Member] \| 2015 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of incentive option granted					With respect to each grant of an ISO to a participant who is not a ten percent stockholder, the exercise price shall not be less than the fair market value of a share on the date the ISO is granted. With respect to each grant of an ISO to a participant who is a ten percent stockholder, the exercise price shall not be less than one hundred ten percent (110%) of the fair market value of a share on the date the ISO is granted.
Maximum aggregate number of Shares with respect to one or more Awards that may be granted to any one person during any calendar year		83,333
Maximum aggregate amount of cash that may be paid in cash to any person during any calendar year \| $		$ 2,000,000
Common Stock [Member] \| Incentive Stock Options [Member] \| Minimum [Member] \| 2015 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employee threshold percentage					10.00%
Purchase price of common stock percentage					110.00%