Stockholders Equity - Additional Information (Detail) (USD $)	9 Months Ended								3 Months Ended	1 Months Ended	9 Months Ended			12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013		Sep. 30, 2014 2009 Unit Offering	Aug. 31, 2009 2009 Unit Offering	Sep. 30, 2014 2010 Unit Offering	Nov. 30, 2010 2010 Unit Offering	Sep. 30, 2014 Warrant 2009 Unit Offering	Nov. 30, 2010 Warrant 2010 Unit Offering	Sep. 30, 2014 Warrant 2010 Unit Offering	Sep. 30, 2014 Stockholder Rights Plan	Sep. 30, 2014 Sales Agreement Cantor	Dec. 31, 2013 Sales Agreement Cantor
Stockholders Equity Note [Line Items]
Warrants to purchase an aggregate shares of common stock						2,400,000		3,700,000
Warrant exercise price						$ 2.90		$ 3.20
Warrants exercisable date										May 15, 2011
Exercisable period										5 years
Warrants exercised									2,400,000		157,894
Warrant liability	$ 3,931,000		$ 20,390,000	[1]	$ 0		$ 3,300,000
Maximum common stock offering price													70,000,000
Percentage of proceeds payable as compensation to underwriter													2.00%
Common stock, number of shares issued													1,700,000	5,400,000
Proceeds from common stock sold	6,849,000	50,981,000											7,100,000	23,500,000
Common stock available for sale													$ 34,400,000
Minimum percentage of common stock acquired by stockholders												15.00%
Designated preferred stock for future issuance												250,000

[1] The financial information in this column was derived from audited financial statements included in the Company's 2013 Annual Report on Form 10-K.