Convertible Debentures (Details) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Jun. 06, 2017 USD ($) shares $ / shares	Jul. 21, 2014 USD ($) shares $ / shares	Jun. 30, 2017 USD ($) $ / shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) shares $ / shares	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / shares
Debt Instrument [Line Items]
Total convertible debt			$ 13,386		$ 13,386		$ 12,028
Aggregate principal amount of debt			$ 40,465		$ 40,465
Common stock, par value (in dollars per share) | $ / shares			$ 0.001		$ 0.001		$ 0.001
Change in fair value of warrant liability			$ (128)	$ (3,199)	$ 4	$ (5,184)
Debentures converted in shares of common stock, value					262	$ 248
Debentures outstanding amount			$ 40,465		$ 40,465
Preferred stock, stated value (in dollars per share) | $ / shares			$ 0.10		$ 0.10		$ 0.10
Senior Secured 2.25% Convertible Debentures [Member]
Debt Instrument [Line Items]
Total convertible debt			$ 8,247		$ 8,247		$ 7,174
Debt instrument, unamortized discount			23,007		23,007		24,314
Deferred financing costs			$ 496		$ 496		524
Senior secured convertible debentures interest rate			2.25%		2.25%
Aggregate principal amount of debt			$ 32,500		$ 32,500
Number of shares debt convertible (in shares) | shares					8,666,668
Senior secured convertible debentures conversion price (in dollars per share) | $ / shares			$ 3.75		$ 3.75
Maturity period					5 years
Maturity date					Jun. 30, 2021
Debt instruments, cumulative conversions					$ 750
Debt instrument, convertible, beneficial conversion feature					27,300
Debentures outstanding amount			$ 32,500		$ 32,500
Senior Secured 2.25% Convertible Debentures [Member] | Maximum [Member]
Debt Instrument [Line Items]
Senior secured convertible debentures conversion price (in dollars per share) | $ / shares			$ 6.90		$ 6.90
Senior Secured 2.25% Convertible Debentures [Member] | Minimum [Member]
Debt Instrument [Line Items]
Senior secured convertible debentures conversion price (in dollars per share) | $ / shares			$ 3.75		$ 3.75
Senior Secured 4% Convertible Debentures [Member]
Debt Instrument [Line Items]
Total convertible debt			$ 5,139		$ 5,139		4,854
Debt instrument, unamortized discount		$ 10,353	3,213		3,213		3,469
Deferred financing costs			$ 363		$ 363		$ 392
Senior secured convertible debentures interest rate			4.00%		4.00%
Aggregate principal amount of debt		$ 15,000	$ 15,000		$ 15,000
Number of shares debt convertible (in shares) | shares		1,169,595
Senior secured convertible debentures conversion price (in dollars per share) | $ / shares		$ 12.825
Maturity period					5 years
Maturity date					Jul. 30, 2021
Debt instruments, cumulative conversions					$ 6,285
Debt instrument, convertible, beneficial conversion feature		$ 4,565
Fair value of warrants		5,296
Change in fair value of warrant liability		491
Debt instrument initial carrying amount		4,647
Debentures converted in shares of common stock, value					$ 262
Debt conversion, converted instrument, issued (in shares) | shares					70,000
Interest expense on debt					$ 197
Debentures outstanding amount		$ 15,000	$ 15,000		$ 15,000
Senior Secured 4% Convertible Debentures [Member] | Series A Warrants [Member]
Debt Instrument [Line Items]
Number of warrants to purchase common stock (in shares) | shares		1,239,769
Exercise price of warrants (in dollars per share) | $ / shares		$ 12.25
Common stock, par value (in dollars per share) | $ / shares		$ 0.001
Warrants expiration date					Jul. 31, 2019
Senior Secured 2.25% Convertible Debentures and Senior Secured 4% Convertible Debentures [Member]
Debt Instrument [Line Items]
Aggregate principal amount of debt	$ 40,652
Debentures outstanding amount	40,652
Debt instrument, interest payment	$ 4,000
Number of years for interest payments					4 years
Number of days for approval					2 days
Senior Secured 2.25% Convertible Debentures and Senior Secured 4% Convertible Debentures [Member] | Series C Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Number of shares debt convertible (in shares) | shares	15,099,000
Senior secured convertible debentures conversion price (in dollars per share) | $ / shares	$ 2.69
Debt conversion, converted instrument, issued (in shares) | shares	40,616
Preferred stock, stated value (in dollars per share) | $ / shares	$ 1,000
Senior Secured 2.25% Convertible Debentures and Senior Secured 4% Convertible Debentures [Member] | Series C Convertible Preferred Stock [Member] | Maximum [Member]
Debt Instrument [Line Items]
Beneficial ownership percentage	9.99%