Fair Value of Financial Assets and Liabilities - Derivative Instruments (Valuation Assumptions Used for Series B Convertible Stock) (Details) - Series B redeemable convertible preferred stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Volatility		91.00%
Fair Value Assumptions, Expected Term		1 year 3 months
Risk-free interest rate		0.36%
Dividend yield	0.00%	0.00%
Exercise price	$ 7.00	$ 7.00
Common stock closing price	$ 3.98	$ 10.50
Minimum [Member]
Volatility	108.00%
Fair Value Assumptions, Expected Term	6 months
Risk-free interest rate	0.49%
Maximum [Member]
Volatility	117.00%
Fair Value Assumptions, Expected Term	2 years 6 months
Risk-free interest rate	1.19%