Debt - Convertible Subordinated Debentures (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions			3 Months Ended
	Jun. 20, 2019	Mar. 29, 2019	Mar. 31, 2019	Mar. 28, 2019	Nov. 28, 2018
Short-term debt
Purchase price			$ 2,000
Carrying amount		$ 1,500
Embedded derivative liability		$ 500
Warrant expense			$ 130
Level 3 | Risk-free interest rate
Short-term debt
Embedded Derivative Liability Measurement Input		2.19
Level 3 | Expected volatility
Short-term debt
Embedded Derivative Liability Measurement Input		161.74
Level 3 | Probability of conversion
Short-term debt
Embedded Derivative Liability Measurement Input		98.0
Level 3 | Probability of repayment at each conversion
Short-term debt
Embedded Derivative Liability Measurement Input		2.0
Level 3 | Option-adjusted spread
Short-term debt
Embedded Derivative Liability Measurement Input		50.0
Level 3 | Discount for lack or marketability
Short-term debt
Embedded Derivative Liability Measurement Input		20.0
Secured subordinated convertible debentures due June 28, 2019
Short-term debt
Purchase price		$ 2,000
Face amount		$ 2,200
Original issue discount		10.00%
Carrying amount		$ 1,500
Repayment of subordinated convertible debentures	$ 2,200
November 28, 2018 Series A investor warrants
Short-term debt
Number of shares in exchange of warrant exercise					8,000,000
Exercise price of warrants (in dollars per share)		$ 0.01		$ 1.50
Warrant expense		$ 100
November 28, 2018 Series A investor warrants | Risk-free interest rate
Short-term debt
Warrant fair value measurement inputs (as a percent)		2.2
November 28, 2018 Series A investor warrants | Expected term
Short-term debt
Warrants term		4 years 8 months 12 days
November 28, 2018 Series A investor warrants | Expected dividends
Short-term debt
Warrant fair value measurement inputs (as a percent)		0
November 28, 2018 Series A investor warrants | Expected volatility
Short-term debt
Warrant fair value measurement inputs (as a percent)		204.4