Stockholders' Equity (Common Stock Narrative) (Details) - USD ($)	1 Months Ended	7 Months Ended	12 Months Ended
	Jul. 31, 2013	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 20, 2016	Jun. 30, 2015
Class of Stock [Line Items]
Proceeds from the sale of common stock		$ 2,400,000
Common stock, shares issued (in shares)		30,696,791	30,696,791	29,737,601
Proceeds from the sale of common stock			$ 2,285,415	$ 61,215,399	$ 0
Net proceeds from the sale of common stock			$ 2,285,415	$ 61,215,399
Shares issued upon exercise of warrants (in shares)			8,333	732,378	36,666
Option exercise price, weighted average of $3.53
Class of Stock [Line Items]
Issuance of common stock upon exercise of stock options (in shares)			1,236,875
Warrant exercise price of $3.00
Class of Stock [Line Items]
Shares issued upon exercise of warrants (in shares)			8,333	449,403
Common Stock
Class of Stock [Line Items]
Shares of common stock issued (in shares)			421,810	9,996,531
Net proceeds from the sale of common stock			$ 42	$ 1,000
Issuance of common stock upon exercise of warrant (in shares)				282,975
Exercise price of warrants (in dollars per share)					$ 3.00
Stock issued during period including share-based compensation (in shares)			959,190	10,821,808
Issuance of common stock upon net exercise of warrant (in shares)			2,651	277,136	13,011
Issuance of common stock upon net exercise of stock option (in shares)			341,333
Issuance of common stock upon exercise of stock options (in shares)			98,396	265,166
Issuance of common stock upon releases of restricted stock units (in shares)			95,000
Common Stock | Option exercise price of $4.50
Class of Stock [Line Items]
Issuance of common stock upon exercise of stock options (in shares)			98,396	265,166
Weighted average price of shares (in dollars per share)			$ 3.73	$ 3.25
Common Stock | Option exercise price, weighted average of $3.53
Class of Stock [Line Items]
Weighted average price of shares (in dollars per share)			$ 3.81
Shares issued upon exercise (in shares)			341,333
Common Stock | Warrant exercise price, weighted average of $5.02
Class of Stock [Line Items]
Exercise price of warrants (in dollars per share)				$ 4.91
Shares issued upon exercise of warrants (in shares)				282,975
Common Stock | Warrant exercise price of $3.00
Class of Stock [Line Items]
Exercise price of warrants (in dollars per share)		$ 3.00	$ 3.00	$ 3.05
Issuance of common stock upon net exercise of warrant (in shares)			2,651	277,136
Public Offering and Controlled Equity Offering
Class of Stock [Line Items]
Proceeds from the sale of common stock	$ 15,000,000
Secured Debt
Class of Stock [Line Items]
Exercise price of warrants (in dollars per share)						$ 4.84
Secured Debt | Loan and Security Agreement
Class of Stock [Line Items]
Exercise price of warrants (in dollars per share)							$ 3.51
Underwritten Public Offering 2015 | Public Offering and Controlled Equity Offering | Common Stock
Class of Stock [Line Items]
Shares of common stock issued (in shares)				9,711,110
Proceeds from the sale of common stock				$ 63,200,000
Price per share (in dollars per share)		$ 5.61	$ 5.61	$ 9.66
Underwritten Public Offering 2015 | Agent | Public Offering and Controlled Equity Offering | Common Stock
Class of Stock [Line Items]
Shares of common stock issued (in shares)			421,810	285,421
Proceeds from the sale of common stock			$ 2,400,000	$ 2,800,000