Convertible Debentures (as restated) (Details) $ / shares in Units, $ in Thousands			3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 20, 2017 USD ($) shares	Jul. 21, 2014 USD ($) shares $ / shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016
Interest and Debt Expense [Abstract]
Number of warrants to purchase common stock (in shares) | shares													403,090	1,860,790
Common stock, par value (in dollars per share) | $ / shares													$ 0.001	$ 0.001
Change in fair value of warrant liability			$ 1,053	$ 263	$ (40)	$ (421)	$ (657)	$ 671	$ 222	$ 14	$ 1,275	$ (407)	$ 0	$ (595)
Debentures converted into shares of common stock, value													0	262
Income (loss) on extinguishment of debentures						$ (20,160)	$ 0	$ 0		$ 0		$ (20,160)	0	(20,160)
Total convertible debt														0
Interest expense related to convertible debenture													$ 0	1,701
Series C Convertible Preferred Stock [Member]
Interest and Debt Expense [Abstract]
Preferred stock conversion price (in dollars per share) | $ / shares													$ 2.69
Debentures converted into shares of common stock, value	$ 40,465
Debt conversion, converted instrument, issued (in shares) | shares	40,482
Beneficial ownership percentage													9.99%
Preferred stock, stated value (in dollars per share) | $ / shares													$ 1,000
Number of shares issuable for each preferred stock converted (in shares) | shares													372
Number of common shares issuable on conversion of preferred stock (in shares) | shares													15,049,000
Senior Secured 2.25% Convertible Debentures and Senior Secured 4% Convertible Debentures [Member] | Series C Convertible Preferred Stock [Member] | Maximum [Member]
Interest and Debt Expense [Abstract]
Beneficial ownership percentage													9.99%
Senior Secured 2.25% Convertible Debentures [Member]
Interest and Debt Expense [Abstract]
Aggregate principal amount of debt													$ 32,500
Number of shares debt convertible (in shares) | shares													8,666,668
Debt instrument conversion price (in dollars per share) | $ / shares													$ 3.75
Interest rate													2.25%
Maturity period													5 years
Maturity date													Jun. 22, 2020
Probability of shareholder													80.00%		0.00%
Probability of shareholder, reset event													20.00%
Probability of remaining outstanding through maturity date															75.00%
Debt discount amortized period													5 years
Senior Secured 2.25% Convertible Debentures [Member] | Stock Price [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs | $ / shares													1.38
Senior Secured 2.25% Convertible Debentures [Member] | Volatility [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0.54
Senior Secured 2.25% Convertible Debentures [Member] | Volatility [Member] | Minimum [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0.469
Senior Secured 2.25% Convertible Debentures [Member] | Volatility [Member] | Maximum [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0.506
Senior Secured 2.25% Convertible Debentures [Member] | Expected Life [Member]
Interest and Debt Expense [Abstract]
Expected term													5 years
Senior Secured 2.25% Convertible Debentures [Member] | Risk Free Interest Rate [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0.0168
Senior Secured 2.25% Convertible Debentures [Member] | Risk Free Interest Rate [Member] | Minimum [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0.0153
Senior Secured 2.25% Convertible Debentures [Member] | Risk Free Interest Rate [Member] | Maximum [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0.0163
Senior Secured 2.25% Convertible Debentures [Member] | Expected Dividend Yield [Member]
Interest and Debt Expense [Abstract]
Valuation methodology and significant inputs													0
Senior Secured 4% Convertible Debentures [Member]
Interest and Debt Expense [Abstract]
Aggregate principal amount of debt		$ 15,000											$ 15,000
Number of shares debt convertible (in shares) | shares		1,169,595
Debt instrument conversion price (in dollars per share) | $ / shares		$ 12.825
Interest rate		4.00%
Maturity period													5 years
Maturity date													Jun. 30, 2021
Debt instrument, unamortized discount		$ 10,352											$ 31,989
Fair value of warrants		5,296
Debt instrument, convertible, beneficial conversion feature		4,565
Change in fair value of warrant liability		491											$ 0	(3,158)
Debt instrument initial carrying amount		$ 4,648
Debentures converted into shares of common stock, value														$ 262
Debt conversion, converted instrument, issued (in shares) | shares														70,000
Senior Secured 4% Convertible Debentures [Member] | Series A Warrants [Member]
Interest and Debt Expense [Abstract]
Number of warrants to purchase common stock (in shares) | shares													1,239,769
Common stock, par value (in dollars per share) | $ / shares													$ 0.001
Exercise price of warrants (in dollars per share) | $ / shares													$ 12.25
Warrants expiration date													Jul. 31, 2019