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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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

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Stockholders' Equity (Deficit) - Additional Information (Detail)				3 Months Ended
	Jul. 09, 2019 shares	Jul. 08, 2019 $ / shares shares	Jun. 09, 2015 USD ($) shares	Mar. 31, 2020 USD ($) d $ / shares shares	Mar. 31, 2019 USD ($)	Dec. 31, 2019 $ / shares shares	Mar. 26, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, par value \| $ / shares				$ 0.0001		$ 0.0001
Preferred stock, shares authorized				24,984,166		24,984,166
Share-based compensation expense \| $				$ 105,162	$ 23,000
Poplar Falls LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants, exercise price \| $ / shares				$ 3.99
Accounting Standards Update 2017-01 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of ownership acquired						79.90%
Bismarck [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business combination number of shares issued or issuable				249,584
Bismarck [Member] \| Accounting Standards Update 2017-01 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of ownership acquired	79.90%
Business combination number of shares issued or issuable	249,584
Note And Warrant Purchase Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants, exercise price \| $ / shares		$ 5.756		$ 12.00
Number of warrants				65,625
Warrants, expiration date		Jul. 12, 2024		Jul. 21, 2021
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		196,135
Note And Warrant Purchase Agreement [Member] \| Second Amendment Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants, exercise price \| $ / shares		$ 5.756
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		196,135
2015 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award authorized by board			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
Preferred stock, shares authorized				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
Preferred stock, shares authorized				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
Maximum [Member] \| Poplar Falls LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock and warrants sold				426,065
Incentive Stock Options [Member] \| 2015 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award authorized by board			450,000
Additional shares authorized for stock-based compensation				200,000
Incentive Stock Options [Member] \| 2019 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award authorized by board							800,000
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				0.00%
Purchase price of common stock percentage				110.00%