Subsequent Events - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Mar. 13, 2017	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Gross proceeds from issuance of common stock			$ 13,750,000	$ 29,447,000
2017 Private Placement Common Stock Warrants | Subsequent Event
Subsequent Event [Line Items]
Stock issued during period		10,323,101
Warrants to purchase common stock, shares		1,720,512
Gross proceeds from issuance of common stock		$ 26,100,000
Warrant exercise price		$ 3.00
Warrant exercisable period		6 months
Warrant expiration period		7 years
At-The-Market Offering Program | Subsequent Event
Subsequent Event [Line Items]
Average market price per share	$ 5.64
Aggregate gross proceeds from issuance of common stock	$ 21,900,000
Directors and/or Officers | 2017 Private Placement Common Stock Warrants | Subsequent Event
Subsequent Event [Line Items]
Warrant exercise price		$ 3.17
Common Stock | 2017 Private Placement Common Stock Warrants | Subsequent Event
Subsequent Event [Line Items]
Stock issued during period		8,602,589
Common Stock | At-The-Market Offering Program | Subsequent Event
Subsequent Event [Line Items]
Stock issued during period	3,900,000
Maximum | At-The-Market Offering Program | Subsequent Event
Subsequent Event [Line Items]
Maximum common stock saleable value		$ 25,000,000