Stockholders' Equity - 2020 Equity Financing - Additional Information (Detail) - USD ($)	1 Months Ended			3 Months Ended		9 Months Ended
	Aug. 31, 2020	Feb. 29, 2020	Jan. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 23, 2020	Jun. 22, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common Stock, Shares Authorized				300,000,000		300,000,000		300,000,000		150,000,000
At-the-Market Offering [Member]
Class of Stock [Line Items]
Common stock shares maximum aggregate offering price	$ 25,000,000.0		$ 20,000,000.0
Stock issuances, sales agent commission maximum percentage	3.00%		3.00%
Common stock issued				6,029,465	1,707,995	6,029,465	1,707,995
Weighted average common stock price per share				$ 0.81	$ 1.50	$ 0.81	$ 1.50
Gross proceeds from issuance of common stock				$ 4,900,000	$ 2,600,000	$ 4,900,000	$ 2,600,000
Share issuance costs				$ 250,000	$ 151,000	$ 250,000	$ 151,000
2020 Equity Financing [Member]
Class of Stock [Line Items]
Common Stock, Shares Authorized									150,000,000
2020 Equity Financing [Member] | Share Offering [Member]
Class of Stock [Line Items]
Common stock issued		15,000,000
Gross proceeds from issuance of common stock		$ 21,750,000
Share issuance costs		$ 1,800,000
Price per share		$ 1.45