Subsequent Event - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Mar. 29, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Common stock par value			$ 0.001	$ 0.001
Proceeds from public offering net of underwriting discounts, commissions and offering expenses			$ 37,469,611	$ 12,649,859
At The Market Facility [Member] | Cantor Fitzgerald And Co [Member]
Subsequent Event [Line Items]
Common stock par value	$ 0.001
Broker commission as percentage of sale proceed	3.00%
At The Market Facility [Member] | Cantor Fitzgerald And Co [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Shares issued during public offering		527,000
Proceeds from public offering net of underwriting discounts, commissions and offering expenses		$ 4,100,000
At The Market Facility [Member] | Cantor Fitzgerald And Co [Member] | Maximum [Member]
Subsequent Event [Line Items]
Expected aggregate gross proceeds from issuance of stock	$ 20,000,000