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