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Common Stock - Issued and Outstanding Shares - Additional Information (Detail) - USD ($) |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 34 Months Ended |
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Apr. 28, 2020 | Dec. 17, 2019 | Jun. 07, 2019 | May 30, 2019 | May 22, 2018 | Sep. 14, 2017 | Mar. 31, 2020 | Jun. 30, 2020 | Jun. 30, 2019 | Mar. 31, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, par value |  |  |  |  |  |  |  | $ 0.001 |  |  | $ 0.001 |  | $ 0.001 | $ 0.001
Common stock, shares issued |  |  |  |  |  |  |  | 1,937,703 |  |  | 1,937,703 |  | 1,937,703 | 1,474,258
Preferred stock, par value |  |  |  |  |  |  |  | $ 0.001 |  |  | $ 0.001 |  | $ 0.001 |
Proceeds from exercise of warrants, net of issuance costs |  |  |  | $ 4,200,000 |  |  |  |  |  |  | $ 589,000 | $ 4,199,000 |  |
Stock option exercises, Shares |  |  |  |  |  |  |  | 0 | 0 |  | 0 | 0 |  |
Restricted stock unit settlements |  |  |  |  |  |  |  | 0 | 6 |  | 0 | 6 |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restricted stock unit settlements |  |  |  |  |  |  |  |  |  | 4 |  |  |  |
December 2019 Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise price per unit of warrant |  | $ 6.60 |  |  |  |  |  |  |  |  |  |  |  |
Offering expenses |  |  |  |  |  |  |  |  |  |  | $ 34,000 |  |  |
Warrant exercisable period |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |
Cancellation of warrant description |  |  |  |  |  |  |  |  |  |  | Additionally, subject to certain exceptions, if, after December 17, 2019, (i) the volume weighted average price of the common stock for each of 30 consecutive trading days, or the 2019 Measurement Period, which 2019 Measurement Period commences on the closing date, exceeds 300% of the exercise price (subject to adjustments for stock splits, recapitalizations, stock dividends and similar transactions), (ii) the average daily trading volume for such 2019 Measurement Period exceeds $500,000 per trading day and (iii) certain other equity conditions are met, and subject to a beneficial ownership limitation, then the Company may call for cancellation of all or any portion of the warrants then outstanding. |  |  |
Number of required consecutive days weighted average trading price for cancelation or recall of warrants |  | 30 days |  |  |  |  |  |  |  |  |  |  |  |
Minimum required trading price percentage over exercise price for cancelation or recall of warrants |  | 300.00% |  |  |  |  |  |  |  |  |  |  |  |
Minimum required trading volume value per day for cancelation or recall of warrants |  | $ 500,000 |  |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from sale of warrants and units |  |  |  |  |  |  |  |  |  |  | $ 13,800,000 |  |  |
Warrant and units offering cost including underwriting discounts and commissions |  |  |  |  |  |  |  |  |  |  | 1,500,000 |  |  |
Net proceeds from issuance of warrants and units |  |  |  |  |  |  |  |  |  |  | $ 12,300,000 |  |  |
April 2020 Private Placement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued | 280,782 |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase shares of common stock | 0.75 |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase shares of common stock, offering price per share | $ 6.60 |  |  |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from issuance of common stock | $ 1,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from exercise of warrants, net of issuance costs | $ 1,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of exercise price exceeds in measurement period |  |  |  |  |  |  |  |  |  |  | 300.00% |  |  |
Average daily trading volume for measurement period |  |  |  |  |  |  |  |  |  |  | $ 500,000 |  |  |
April 2020 Private Placement [Member] | Placement Agent [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise price per unit of warrant | $ 7.59 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of common shares issuable conversion of warrants | 25,270 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of cash commission in gross proceeds from sale of units | 9.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase common stock | 25,270 |  |  |  |  |  |  |  |  |  |  |  |  |
April 2020 Private Placement [Member] | Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued |  |  |  |  |  |  |  | 280,782 |  |  |  |  |  |
Series A Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, par value |  |  |  |  |  |  |  | $ 0.001 |  |  | $ 0.001 |  | $ 0.001 | $ 0.001
Preferred stock, shares outstanding |  |  |  |  |  |  |  | 0 |  |  | 0 |  | 0 | 0
Series B Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, par value |  |  |  |  |  |  |  | $ 0.001 |  |  | $ 0.001 |  | $ 0.001 | $ 0.001
Preferred stock, shares outstanding |  |  |  |  |  |  |  | 0 |  |  | 0 |  | 0 | 1,121
Series B Convertible Preferred Stock [Member] | December 2019 Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares converted |  |  |  |  |  |  |  |  |  |  | 6,256 |  |  |
Preferred stock, shares outstanding |  |  |  |  |  |  |  | 0 |  |  | 0 |  | 0 |
Series B Convertible Preferred Stock [Member] | December 2019 Public Offering [Member] | Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Convertible preferred stock, shares issued upon conversion |  |  |  |  |  |  |  |  |  |  | 521,124 |  |  |
Maximum [Member] | December 2019 Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise price per unit of warrant |  | $ 1.20 |  |  |  |  |  |  |  |  |  |  |  |
Subscription Agreements Executed on April 27, 2020 [Member] | April 2020 Private Placement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise price per unit of warrant |  |  |  |  |  |  |  | $ 7.24 |  |  | $ 7.24 |  | $ 7.24 |
Subscription Agreements Executed on April 28, 2020 [Member] | April 2020 Private Placement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise price per unit of warrant |  |  |  |  |  |  |  | $ 7.32 |  |  | $ 7.32 |  | $ 7.32 |
Class A Units [Member] | December 2019 Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of new units in a public offering |  | 478,875 |  |  |  |  |  |  |  |  |  |  |  |
Public offering, price per unit |  | $ 12.00 |  |  |  |  |  |  |  |  |  |  |  |
Description of stock units issued |  |  |  |  |  |  |  |  |  |  | Each Class A Unit consisted of one share of our common stock and a warrant to purchase one share of common stock. |  |  |
Class B Units [Member] | December 2019 Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of new units in a public offering |  | 6,256 |  |  |  |  |  |  |  |  |  |  |  |
Public offering, price per unit |  | $ 999.60 |  |  |  |  |  |  |  |  |  |  |  |
Description of stock units issued |  |  |  |  |  |  |  |  |  |  | Each Class B Unit consisted of one share of Series B Convertible Preferred Stock, par value $0.001 per share, convertible at any time at the holder’s option into approximately 83 shares of common stock, and warrants to purchase approximately 83 shares of common stock. |  |  |
Number of common shares issuable for each share of convertible preferred stock |  | 83 |  |  |  |  |  |  |  |  |  |  |  |
Number of common shares issuable conversion of warrants |  | 83 |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase common stock |  | 83 |  |  |  |  |  |  |  |  |  |  |  |
Class B Units [Member] | Series A Convertible Preferred Stock [Member] | December 2019 Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, par value |  | $ 0.001 |  |  |  |  |  |  |  |  |  |  |  |
LPC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock value right to sell, maximum |  |  |  |  |  | $ 11,000,000 |  |  |  |  |  |  |  |
Common stock, par value |  |  |  |  |  | $ 0.001 |  |  |  |  |  |  |  |
Minimum percentage of common stock shares outstanding authorized to sell |  |  |  |  | 20.00% |  |  |  |  |  |  |  |  |
Initial purchase of common stock |  |  |  |  |  |  |  |  |  |  |  |  | 1,644 |
Common stock, shares issued |  |  |  |  |  | 617 |  |  |  |  |  |  |  |
Payments related to expense reimbursement |  |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |
Common stock, shares issued |  |  |  |  |  |  |  | 0 |  |  | 0 |  | 27,868 |
Gross proceeds |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,400,000 |
Offering expenses |  |  |  |  |  |  |  |  |  |  |  |  | 500,000 |
Common stock available for sale under offering |  |  |  |  |  |  |  | $ 6,600,000 |  |  | $ 6,600,000 |  | 6,600,000 |
LPC [Member] | Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, purchase price |  |  |  |  |  | $ 1.00 |  |  |  |  |  |  |  |
Additional common stock value right to sell, maximum |  |  |  |  |  | $ 10,000,000 |  |  |  |  |  |  |  |
Additional purchase of common stock, maximum |  |  |  |  |  | 7,500 |  |  |  |  |  |  |  |
Offering expenses |  |  |  |  |  |  |  |  |  |  | $ 14,000 |  |  |
LPC [Member] | Units [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial purchase of common stock |  |  |  |  |  | 1,644 |  |  |  |  |  |  |  |
Common stock, purchase price |  |  |  |  |  | $ 608.00 |  |  |  |  |  |  |  |
Purchase agreement, description |  |  |  |  |  |  |  |  |  |  | Unit consisting of (a) one share of our common stock and (b) one warrant to purchase one-quarter of a share of common stock at an exercise price of $699.20 per share, or Warrant. Each Warrant became exercisable six months following the issuance date until the date that is five years and six months after the issuance date and is subject to customary adjustments. |  |  |
Exercise price per unit of warrant |  |  |  |  |  | $ 699.20 |  |  |  |  |  |  |  |
Initial purchase of units consisting of common stock and warrants issued |  |  |  |  |  | $ 1,000,000 |  |  |  |  |  |  |  |
LPC [Member] | Other Units [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of warrants issued |  |  |  |  |  | 0 |  |  |  |  |  |  |  |
H.C. Wainwright [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, par value |  |  | $ 0.001 |  |  |  |  |  |  |  |  |  |  |
Common stock available for sale under offering |  |  |  |  |  |  |  | $ 6,000,000 |  |  | $ 6,000,000 |  | $ 6,000,000 |
Percentage of commission on gross proceeds from sale of common stock |  |  | 3.00% |  |  |  |  |  |  |  |  |  |  |
H.C. Wainwright [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock value right to sell, maximum |  |  | $ 6,000,000 |  |  |  |  |  |  |  |  |  |  |
Ladenburg Thalmann & Co. Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period granted for underwriting option |  | 45 days |  |  |  |  |  |  |  |  |  |  |  |
Ladenburg Thalmann & Co. Inc [Member] | 2019 Overallotment Option [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional purchase of common stock and warrants, maximum |  | 150,000 |  |  |  |  |  |  |  |  |  |  |  |
Overallotment option exercise date |  | Dec. 17, 2019 |  |  |  |  |  |  |  |  |  |  |  |

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