Convertible Preferred Shares - Additional Information (Detail) - $ / shares				12 Months Ended
	Nov. 16, 2018	Nov. 15, 2018	Jul. 17, 2018	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Preferred stock, shares authorized				10,000,000		10,000,000
Preferred stock, par value				$ 0.001		$ 0.001
Common stock, par value				$ 0.001		$ 0.001
BVF [Member]
Class Of Stock [Line Items]
Issuance of preferred stock in exchange for shares of common stock		1,000,000
Common stock, par value		$ 0.001
Series A Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Number of shares issuable upon conversion					500,000
Series B Convertible Preferred Stock [Member] | BVF [Member]
Class Of Stock [Line Items]
Preferred stock, shares authorized	1,000
Preferred stock, par value		$ 0.001
Share price	$ 7,950
Number of shares issuable upon conversion	1,000	1,000
Percentage of shares owned by share holders	9.99%
Preferred stock, liquidation per share	$ 0.001
Underwritten Public Offering [Member] | Series A Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Issuance of stock, shares			2,220
Share price			$ 12,500
Number of shares issuable upon conversion			1,000	1,000
Percentage of shares owned by share holders				9.99%
Preferred stock, liquidation per share				$ 0.001
Voting rights				no