Stockholders' Deficit (Details) - USD ($)		9 Months Ended
	Mar. 05, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Stockholders' Deficit
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001		$ 0.0001
Gross proceeds from sale of common stock by the entity (in dollars)		$ 14,672,000	$ 25,612,000
Selling agent fees		$ 404,000
June 2012 Amended Controlled Equity Offering Sales Agreement
Stockholders' Deficit
Additional aggregate offering price of common stock	$ 50,000,000
Common stock sold by the entity (in shares)		3,435,998
Gross proceeds from sale of common stock by the entity (in dollars)		$ 14,700,000
Common stock price (in dollars per share)		$ 4.27
Selling agent fees		$ 400,000
June 2012 Amended Controlled Equity Offering Sales Agreement | Maximum
Stockholders' Deficit
Selling agent fee as a percentage of gross sales price per share sold	3.00%