Organization and Basis of Presentation - Narrative (Detail) (USD $)	0 Months Ended	12 Months Ended
	Nov. 12, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 27, 2013
Disclosure Organization And Basis Of Presentation Additional Information [Abstract]
Common Stock, Value, Authorized					$ 25,000,000.0
Common Stock, Shares, Issued		6,753,104
Sale of Stock, Price Per Share		$ 1.66
Issuance of common stock from initial public offering		10,834,000
Proceeds from issuance of common stock and common stock warrants, net of issuance costs	64,471,000	75,690,000	67,316,000	59,527,000
Underwriting discounts and commissions paid	4,140,000
Offering expenses	$ 389,000
Sale of shares of common stock	30,666,667
Shares sold from over-allotment option	4,000,000
Purchase price of common stock (in usd per share)	$ 2.25