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Stockholders' Equity - Additional Information (Detail) - USD ($) |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Dec. 31, 2019 | May 31, 2018 | Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2018 | Nov. 30, 2017
Class of Stock [Line Items] |  |  |  |  |  |
Issuance of common stock and warrants |  |  | $ 69,231,000 | $ 220,000 | $ 70,151,000 |
Fair value of warrants |  | $ 36,600,000 | 40,483,000 | $ 17,613,000 | $ 17,600,000 |
Aggregate value of securities available under shelf registration statement |  |  | $ 400,000 |  |  |
Total authorized share capital |  |  | 226,100,000 |  |  |
Common stock, shares authorized |  |  | 226,000,000 | 226,000,000 |  |
Common stock, par value |  |  | $ 0.00000002 | $ 0.00000002 |  |
Preferred stock, shares authorized |  |  | 100,000 | 100,000 |  |
Preferred stock, par value |  |  | $ 0.01 | $ 0.01 |  |
Common stock voting rights |  |  | one vote per share |  |  |
Preferred stock, shares outstanding |  |  | 0 | 0 |  |
Warrants exercised for common stock |  |  | $ 440,043 |  |  |
Proceeds from warrant exercised |  |  | 0 | $ 1,118,000 |  |
Common stock Value Issued |  |  | 69,231,000 | $ 5,444,000 |  |
Unsold Securities Shares and Warrants Under Agreement |  |  | 107,500,000 |  |  |
Aggregate Value of Securities Available Under Agreement |  |  | 178,900,000 |  |  |
Remaining Available Under ATM Sales Agreement |  |  | $ 3,200,000 |  |  |
ATM Sales Agreement |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Common stock share issued |  |  | 5,471,684 |  |  |
Common stock Value Issued |  |  | $ 20,700,000 |  |  |
Private Placement |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Issuance of common stock and warrants |  | $ 70,200,000 |  |  |  |
Common stock share issued |  | 33,003,296 |  |  |  |
Common stock share issued, per share |  | $ 2.27 |  |  |  |
Number of warrants to purchase |  | 16,501,645 |  |  |  |
Exercise price |  | $ 2.54 |  |  |  |
Warrants expiration date |  |  | 2023-05 |  |  |
Warrants outstanding |  |  | 16,061,602 |  |  |
Underwritten Registered Offering |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Offering price per share | $ 1.60 |  |  |  |  |
Proceeds from offering net of costs | $ 48,500,000 |  |  |  |  |
Stock Issuance Costs | $ 3,300,000 |  |  |  |  |
Number of shares offered | 32,343,750 |  |  |  |  |
Maximum |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Sale of shares and warrants under agreement |  |  | $ 200,000,000 |  |  |
Maximum | ATM Sales Agreement |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Sale of shares under agreement |  |  |  |  |  | $ 30,000,000

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