Stockholders' Equity (Details) (USD $)	9 Months Ended				0 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 05, 2014	Dec. 31, 2013	Mar. 05, 2014 June 2012 Amended Controlled Equity Offering Sales Agreement	Sep. 30, 2014 June 2012 Amended Controlled Equity Offering Sales Agreement	Mar. 05, 2014 June 2012 Amended Controlled Equity Offering Sales Agreement Maximum
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.0001		$ 0.0001	$ 0.0001
Additional aggregate offering price of common stock					$ 50,000,000
Commission payable to Cantor as a percentage of gross sales price per share sold							3.00%
Common stock sold by the entity (in shares)						4,604,130
Gross proceeds from sale of common stock by the entity (in dollars)	25,612,000	94,734,000				25,600,000
Common stock, average selling price (in dollars per share)						$ 5.56
Selling agent fees	706,000					706,340
Proceeds from exercise of stock options	$ 36,000	$ 119,000