Description of Business and Basis of Preparation - Additional Information (Detail) - USD ($)					6 Months Ended
	Sep. 30, 2016	Jun. 21, 2016	Apr. 10, 2016	Nov. 16, 2015	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Jul. 31, 2006
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of warrants issued to purchase common stock (in shares)					14,033		14,033
Net proceeds from the June 2016 Public Offering					$ 5,056,000
Underwriting discounts and commissions and offering expenses					$ 168,000	$ 1,765,000
Term Loan | Secured Debt
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Loan agreement term	48 months
Term loan, face amount	$ 15,000,000
June 2016 Public Offering
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock issued under Shelf Registration, net of expenses (in shares)		9,375,000
Number of warrants issued to purchase common stock (in shares)		4,218,750
Share price (in dollars per share)		$ 2.40
Exercise price of warrants (in dollars per share)		$ 3.00
Net proceeds from the June 2016 Public Offering		$ 20,800,000
Underwriting discounts and commissions and offering expenses		$ 1,700,000
Common Stock
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Shelf registration maximum equity offering price				$ 150,000,000
Number of warrants issued to purchase common stock (in shares)								14,033
Exercise price of warrants (in dollars per share)								$ 45.61
Common Stock | Sales Agreement
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Shelf registration maximum equity offering price			$ 40,000,000	$ 40,000,000