Subsequent Events - Additional Information (Detail)				12 Months Ended
	Jan. 18, 2018 USD ($) d $ / shares shares	Jan. 15, 2018 USD ($)	Oct. 23, 2017 shares	Dec. 31, 2017 $ / shares shares	Dec. 31, 2015 shares	Dec. 13, 2017 $ / shares	Jun. 29, 2017 $ / shares	Apr. 18, 2017 $ / shares	Dec. 31, 2016 $ / shares shares
Subsequent Event [Line Items]
Common stock, shares issued | shares				119,053,414					95,680,831
Common stock, par value				$ 0.01		$ 0.01			$ 0.01
Common Stock
Subsequent Event [Line Items]
Number of shares sold in underwritten public offering | shares			973,236	173,000	1,788,000
Senior convertible notes due December 31, 2019
Subsequent Event [Line Items]
Exchange price per share							$ 1.45	$ 1.22
Senior convertible notes due December 31, 2019 | Deerfield | Tranche B Exchange Shares
Subsequent Event [Line Items]
Exchange price per share								$ 1.15
Subsequent Event | Senior convertible notes due December 31, 2019 | Deerfield | Fifth Amendment to Facility Agreement
Subsequent Event [Line Items]
Deferred payment of credit facility principal amount | $		$ 4,400,000
Subsequent Event | Senior convertible notes due December 31, 2019 | Deerfield | Sixth Amendment to Facility Agreement
Subsequent Event [Line Items]
Deferred payment of credit facility principal amount | $	$ 1,250,000
Common stock, shares issued | shares	1,267,972
Common stock, par value	$ 0.01
Conversion of notes to common shares, value | $	$ 3,157,251
Exchange price per share	$ 2.49
Subsequent Event | Senior convertible notes due December 31, 2019 | Deerfield | Sixth Amendment to Facility Agreement | Tranche B Exchange Shares
Subsequent Event [Line Items]
Number of trading days | d	3
Conversion price of shares	$ 2.75
Subsequent Event | Senior convertible notes due December 31, 2019 | Deerfield | Sixth Amendment to Facility Agreement | Common Stock | Tranche B Exchange Shares
Subsequent Event [Line Items]
Number of shares sold in underwritten public offering | shares	10,000,000