Stockholders' Equity (Additional Information) (Detail) - USD ($)					3 Months Ended
	Feb. 13, 2017	Dec. 04, 2015	Nov. 18, 2014	May 24, 2013	Mar. 31, 2017	Mar. 31, 2016	Feb. 06, 2017	Dec. 31, 2016	Jul. 29, 2016	Jun. 28, 2016	May 10, 2016	Jan. 12, 2016	May 08, 2013
Class of Stock [Line Items]
Preferred stock, shares authorized					5,000,000			5,000,000
Preferred stock, par value (usd per share)					$ 0.0001			$ 0.0001
Common stock, shares authorized					350,000,000			275,000,000
Common stock, par value (usd per share)					$ 0.0001			$ 0.0001
Proceeds from Issuance or Sale of Equity					$ 5,000	$ 78,000
Exercise price (usd per share)					$ 79.40			$ 79.40	$ 8.60	$ 8.60	$ 30.20		$ 49.40
Lincoln Park Capital, LLC Purchase Agreement [Member]
Class of Stock [Line Items]
Proceeds from Issuance or Sale of Equity			$ 4,900,000
Purchase Agreement Term			36 months
Stock Issued During Period, Shares, Purchase of Assets			125,000
Share Price			$ 40.00
MLV & Co. LLC and Maxim Group LLC [Member]
Class of Stock [Line Items]
At Market Issuance Sales Agreements, Percent of Gross Proceeds				3.00%
At Market Issuance Sales Agreements, Maximum Gross Proceeds		$ 20,000,000		$ 20,000,000
Common Stock [Member] | Lincoln Park Capital, LLC Purchase Agreement [Member]
Class of Stock [Line Items]
Proceeds from Issuance or Sale of Equity			$ 50,000,000
Issuance of common stock, shares			31,561
Common Stock [Member] | Underwritten Public Offering [Member]
Class of Stock [Line Items]
Issuance of common stock, shares	17,000,000
Exercise price (usd per share)	$ 1.10
Proceeds From Issuance or Sale of Equity, Net Underwriting Discounts, Commissions and Offering Expenses	$ 15,500,000
Stock purchase price per share (usd per share)												$ 1.00
New warrants issued during period (in shares)	17,000,000
Class Of Warrant Or Right, Issued, Fair Value	$ 10,400,000
Minimum [Member] | Lincoln Park Capital, LLC Purchase Agreement [Member]
Class of Stock [Line Items]
Stock Purchase Agreement, Authorized Amount							$ 55,000,000
Maximum [Member] | Lincoln Park Capital, LLC Purchase Agreement [Member]
Class of Stock [Line Items]
Stock Purchase Agreement, Authorized Amount							$ 15,600,000