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Common and Preferred Stock (Details Textual) - USD ($) |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | ---
Oct. 15, 2018 | Oct. 10, 2018 | Sep. 11, 2017 | Aug. 05, 2016 | Oct. 31, 2018 | Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018 | Dec. 31, 2017
Preferred Stock, Dividend Rate, Percentage |  |  |  |  |  |  |  | 2.00% |
Preferred Stock Dividends, Income Statement Impact |  |  |  |  |  |  |  |  | $ 6,900,000
Dividends Payable, Current |  |  |  |  |  | $ 61,000 | $ 59,000 |  |
Proceeds from Issuance of Common Stock |  |  |  |  |  |  |  | $ 12,200,000 |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | 13,672,173 |  |  |  |  |  |  |  |
Convertible Preferred Stock, Terms of Conversion |  |  |  |  | The Company may not effect, and the holder will not be entitled to, exercise any Warrants or conversion of the Series B Preferred Stock, which, upon giving effect to such exercise, would cause (i) the aggregate number of shares of Common Stock beneficially owned by the holder (together with its affiliates) to exceed 4.99% (or, at the election of the holder, 9.99%) of the number of shares of Common Stock outstanding immediately after giving effect to the exercise, or (ii) the combined voting power of the Company’s securities beneficially owned by the holder (together with its affiliates) to exceed 4.99% (or, at the election of the holder, 9.99%) of the combined voting power of all of the Company’s securities then outstanding immediately after giving effect to the exercise or conversion, as such percentage ownership is determined in accordance with the terms of the October 2018 Warrants or Series B Preferred Stock. However, any holder may increase or decrease such percentage to any other percentage not in excess of 9.99% upon at least 61 days’ prior notice from the holder to the Company. The holders of the Series B Preferred will participate, on an as-if-converted-to-common stock basis, in any dividends to the holders of common stock. Upon a defined Fundamental Transaction, the holders of the Series B Preferred Stock are entitled to the same consideration as are holders of Common Stock. The Series B Preferred Stock ranks junior to existing Series A preferred stock but on parity with common stock. Liquidation preference is equal to an amount pari passu with the common stock on an as converted basis (i.e., there is no preference to common stock) |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ 1.38 |  |  |  | $ 1.38 |  |  |  |
Shares Issued, Price Per Share | $ 1.15 |  |  |  |  |  |  |  |
Preferred Stock Redemption Discount |  |  |  |  |  |  |  | $ 9,100,000 |
Percentage of issue of the public offering |  |  |  |  | 120.00% |  |  |  |
Preferred Stock Shares Converted |  |  |  |  |  | 1,036 |  |  |
Preferred Stock, Discount on Shares |  |  |  |  |  | $ 400,000 |  |  |
Conversion of Stock, Shares Converted |  |  |  |  |  | 7,598 |  |  |
Common Stock, Discount on Shares |  |  |  |  |  | $ 2,900,000 |  |  |
Investment Warrants Expiration Date1 |  |  |  |  | Oct. 15, 2023 |  |  |  |
Proceeds from Issuance or Sale of Equity | $ 18,600,000 |  |  |  |  |  |  |  |
Over-Allotment Option [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues | 2,428,825 | 2,428,825 |  |  |  |  |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | 2,428,825 | 2,428,825 |  |  |  |  |  |  |
Issue of warrants to purchase common stock |  | 1,807,826 |  |  |  |  |  |  |
Fbr Capital Markets Co [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues |  |  |  |  |  |  |  | 3,500,000 | 300,000
Stock Issued During Period, Value, New Issues |  |  |  | $ 40,000,000 |  |  |  |  |
Brokerage Commission percentage |  |  |  | 3.00% |  |  |  |  |
Proceeds from Issuance of Common Stock |  |  |  |  |  |  |  | $ 12,200,000 | $ 6,400,000
Series A Preferred Stock [Member] |  |  |  |  |  |  |  |  |
Preferred Stock, Par or Stated Value Per Share |  |  |  |  |  | $ 0.001 |  | $ 0.001 |
Preferred Stock, Dividend Rate, Percentage |  |  | 2.00% |  |  |  |  |  |
Preferred Stock Conversion Price Per Share |  |  | $ 18.90 |  |  |  |  |  |
Preferred Stock, Redemption Terms |  |  | (i) the VWAP (as defined in the Certificate of Designation) for at least 20 trading days in any 30 trading day period is greater than $70.00, subject to adjustment in the case of stock split, stock dividends or the like the Company has the right, after providing notice not less than 6 months prior to the redemption date, to redeem, in whole or in part, on a pro rata basis from all holders thereof based on the number of shares of Series A Preferred Stock then held, the outstanding Series A Preferred Stock, for cash, at a redemption price per share of Series A Preferred Stock of $7,875​​​​​​​, subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the Series A Convertible Preferred Stock, or (ii) the five year anniversary of the issuance date, the Company has the right to redeem, in whole or in part, on a pro rata basis from all holders thereof based on the number of shares of Series A Convertible Preferred Stock then held, the outstanding Series A Preferred Stock, for cash, at a redemption price per share equal to the Liquidation Value |  |  |  |  |  |
Preferred Stock Dividends, Income Statement Impact |  |  |  |  |  | $ 61,000 | 59,000 |  |
Series A Preferred Stock [Member] | Private Placement [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues |  |  | 120,000 |  |  |  |  |  |
Preferred Stock, Par or Stated Value Per Share |  |  | $ 0.001 |  |  |  |  |  |
Proceeds from Issuance of Convertible Preferred Stock |  |  | $ 12,000,000 |  |  |  |  |  |
Sale of Stock, Consideration Received Per Transaction |  |  | $ 100 |  |  |  |  |  |
Series B Preferred Stock [Member] |  |  |  |  |  |  |  |  |
Preferred Stock, Par or Stated Value Per Share | $ 1,000 |  |  |  |  | $ 1,000 |  | $ 1,000 |
Preferred Stock Dividends, Income Statement Impact |  |  |  |  |  | $ 398,000 | $ 0 |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | 13,672,173 |  |  |  |  |  |  |  |
Stock Issued During Period, Value, Issued for Services | $ 1,000 |  |  |  |  |  |  |  |
Conversion of Stock, Shares Converted | 13,672,173 |  |  |  |  |  |  |  |
Common Class A [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues | 2,520,000 |  |  |  |  |  |  |  |
Common Class B [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues | 15,723 |  |  |  |  |  |  |  |
Preferred Stock Conversion Price Per Share | $ 1.15 |  |  |  |  |  |  |  |

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