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Liquidity (Details) |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 4 Months Ended | 6 Months Ended | 9 Months Ended |  |  |
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Aug. 05, 2019 $ / shares | Apr. 25, 2019 USD ($) | Apr. 24, 2019 USD ($) | Sep. 21, 2018 USD ($) | Aug. 28, 2018 $ / shares | Jul. 25, 2018 USD ($) $ / shares shares | Jun. 01, 2018 USD ($) | May 23, 2018 $ / shares shares | Oct. 31, 2019 USD ($) shares | Sep. 30, 2019 USD ($) $ / shares shares | Aug. 31, 2019 $ / shares shares | Sep. 30, 2019 USD ($) $ / shares shares | Jun. 30, 2019 USD ($) shares | Mar. 31, 2019 USD ($) shares | Sep. 30, 2018 USD ($) shares | Jun. 30, 2018 USD ($) shares | Mar. 31, 2018 USD ($) shares | Dec. 31, 2018 USD ($) $ / shares shares | Jun. 30, 2019 USD ($) | Sep. 30, 2019 USD ($) $ / shares shares | Sep. 30, 2018 USD ($) | Aug. 16, 2019 shares | May 24, 2018 shares | Dec. 31, 2017 USD ($)
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations |  |  |  |  |  |  |  |  |  |  |  | $ 526,000 |  |  | $ (1,396,000) |  |  |  |  | $ (4,203,000) | $ (6,868,000) |  |  |
Accumulated deficit |  |  |  |  |  |  |  |  |  | $ (426,154,000) |  | $ (426,154,000) |  |  |  |  |  | $ (414,383,000) |  | $ (426,154,000) |  |  |  |
Substantial doubt about going concern, description |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | These factors raise substantial doubt about our ability to continue as a going concern. |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  | 6,723 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares | $ 0.001 |  |  |  |  |  |  | $ 0.001 |  | $ 0.001 |  | $ 0.001 |  |  |  |  |  | $ 0.001 |  | $ 0.001 |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  |  |  | 23,400,000 |  | 50 |  | 50 |  |  |  |  |  |  |  | 50 |  |  | 2,300,000 |
Exercise of warrants | shares |  |  |  |  |  |  |  |  |  |  |  | 490 |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from offering |  |  |  |  |  |  |  |  |  | $ 13,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,789,000 | 0 |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15,964,000 | 6,246,000 |  |  |
Proceeds from issuance warrants |  |  |  |  |  | $ 5,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  | 491,000 | 0 |  |  |
Reverse stock split of common stock | 0.02 |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' equity (deficit) |  |  |  |  |  |  |  |  |  | 160,000 |  | $ 160,000 | $ (6,276,000) | $ 3,857,000 | 6,138,000 | $ 4,751,000 | $ 8,480,000 | $ 5,225,000 | $ (6,276,000) | 160,000 | $ 6,138,000 |  |  | $ 13,000,000
Common stock issued, value |  |  |  |  |  |  |  |  |  |  |  |  | 64,000 | $ 1,873,000 | $ 3,686,000 | $ (297,000) | $ 27,000 |  |  |  |  |  |  |
Nasdaq Stock Market LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split of common stock |  |  |  |  |  |  |  |  |  |  | 0.02 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of consecutive business days no longer able to meet the required closing bid price of common stock |  |  |  |  | 30 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum bid price of common stock required for Nasdaq listing rule | $ / shares |  |  |  |  | $ 1.00 |  |  |  |  |  | $ 1.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Grace period provided with minimum bid price for Nasdaq listing rule |  |  |  |  | 180 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grace date for minimum bid price requirement for Nasdaq listing |  |  |  |  | Feb. 25, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock minimum bid price required to regain compliance | $ / shares |  |  |  |  | $ 1.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of consecutive business days required to regain compliance |  |  |  |  | 10 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Date to regain compliance after meeting continued listing requirement |  |  |  |  | Aug. 26, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional grace period provided with minimum bid price to regain compliance |  |  |  |  | 180 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' equity (deficit) |  |  |  |  |  |  |  |  |  | (160,000,000) |  | (160,000,000) | $ 6,300,000 |  |  |  |  |  | $ 6,300,000 | (160,000,000) |  |  |  |
Minimum stockholders equity requirement |  |  |  |  |  |  |  |  |  | $ 2,500,000 |  | $ 2,500,000 |  |  |  |  |  |  |  | $ 2,500,000 |  |  |  |
Minimum shares requirement for continued listing | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 500,000 |  |
Description of compliance with minimum bid price requirement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | We were also granted an additional compliance period of 180 calendar days, or until August 26, 2019, in which to regain compliance after meeting the continued listing requirement for market value of publicly held shares and all other initial listing standards for the Nasdaq Capital Market, with the exception of the bid price requirement, and providing notice to Nasdaq staff of our intent to cure the deficiency during this second compliance period, by effecting a reverse stock split, if necessary. |  |  |  |  |
Shares, Outstanding | shares |  |  |  |  |  |  |  |  |  |  | 786,807 |  |  |  |  |  |  |  |  |  |  |  |  |
UK Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary |  |  | $ 3,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Japanese Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary |  | $ 2,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,450,000 |  |  |  |
Sale of Stock, Price Per Share | $ / shares |  |  |  |  |  |  |  |  |  | $ 5.00 |  | $ 5.00 |  |  |  |  |  |  |  | $ 5.00 |  |  |  |
Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  |  |  |  |  | 75,000 |  | 75,000 |  |  |  |  |  |  |  | 75,000 |  |  |  |
Warrant exercise price | $ / shares |  |  |  |  |  |  |  |  |  | $ 6.25 |  | $ 6.25 |  |  |  |  |  |  |  | $ 6.25 |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  | 6,723 |  |  |  |  |  |  | 5,000 | 139,855 | 29,407 | 192 | 202 |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  | 141,183 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise of warrants | shares |  |  |  |  |  |  |  |  | 1,039,000 |  |  |  |  |  |  |  |  |  |  | 1,672,000 |  |  |  |
Warrant exercise price | $ / shares |  |  |  |  |  | $ 39.93 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' equity (deficit) |  |  |  |  |  |  |  |  |  | $ 3,000 |  | $ 3,000 |  |  |  |  |  |  |  | $ 3,000 |  |  |  |
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining availability under financing facility |  |  |  |  |  |  |  |  |  | $ 0 |  | $ 0 |  |  |  |  |  |  |  | $ 0 |  |  |  |
Common Stock [Member] | Lincoln Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,802 |  | 32,170 |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300,000 |  | $ 300,000 |  |  |  |
Common stock issued, value |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period exercisable from the date of issuance |  |  |  | 24 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | Maximum [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  | $ 6,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | Maximum [Member] | Lincoln Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining availability under financing facility |  |  |  | $ 100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common Class A [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 289,000 |  |  |  |
Common Class B [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  |  |  |  |  | 2,711,000 |  | 2,711,000 |  |  |  |  |  |  |  | 2,711,000 |  |  |  |
Series C Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  | 7,059,150 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of convertible shares converted into common stock (in shares) | shares |  |  |  |  |  | 200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Series C Convertible Preferred Stock [Member] | Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of convertible shares converted into common stock (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,653 |  |  |  |  |  |  |  |  |  |
Underwriter |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Underwritten public offering description |  |  |  |  |  |  |  |  |  | pursuant to which the Company sold in an underwritten public offering an aggregate of (i) 289,000 Class A Units, each consisting of one share of common stock, par value $0.001 per share, of the Company and one Series U Warrant to purchase one share of Common stock, and (ii) 2,711,000 Class B Units, each consisting of one pre-funded Series V Warrant to purchase one share of Common stock and one Series U Warrant to purchase one share of Common stock at a public offering price of $5.00 per Class A Unit and $4.9999 per Class B Unit (“September 2019 Offering”). In addition, the Company granted the Underwriters a 45-day option to purchase up to an additional 450,000 shares of the Company’s Common stock and/or Series U Warrants at the public offering price, less the underwriting discounts and commissions. The Underwriters exercised their option to purchase an additional 450,000 Series U Warrants. The Company also issued to the Representative warrants (in the form of the Series U Warrants) to purchase 75,000 shares of common stock with an exercise price of $6.25 per share of common stock (“Representative Warrants”). |  |  |  |  |  |  |  |  |  |  |  |  |  |
Option vesting period |  |  |  |  |  |  |  |  |  | 45 days |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant granted | shares |  |  |  |  |  |  |  |  |  | 450,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Underwriter | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Option granted | shares |  |  |  |  |  |  |  |  |  | 450,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Underwriter | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise of warrants | shares |  |  |  |  |  |  |  |  |  | 450,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Underwriter | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  |  |  |  |  | 75,000 |  | 75,000 |  |  |  |  |  |  |  | 75,000 |  |  |  |
Warrant exercise price | $ / shares |  |  |  |  |  |  |  |  |  | $ 6.25 |  | $ 6.25 |  |  |  |  |  |  |  | $ 6.25 |  |  |  |
Underwriter | Common Class A [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  |  |  |  |  | 289,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  | $ 0.001 |  | 0.001 |  |  |  |  |  |  |  | 0.001 |  |  |  |
Underwriter | Common Class A [Member] | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of Stock, Price Per Share | $ / shares |  |  |  |  |  |  |  |  |  | $ 5.00 |  | $ 5.00 |  |  |  |  |  |  |  | $ 5.00 |  |  |  |
Underwriter | Common Class B [Member] | Series V Warrants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  |  |  |  |  | 2,711,000 |  | 2,711,000 |  |  |  |  |  |  |  | 2,711,000 |  |  |  |
Underwriter | Common Class B [Member] | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of Stock, Price Per Share | $ / shares |  |  |  |  |  |  |  |  |  | $ 4.9999 |  | $ 4.9999 |  |  |  |  |  |  |  | $ 4.9999 |  |  |  |
Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue received in cash |  |  |  |  |  |  |  |  | $ 4,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event | Barda Contract [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue received in cash |  |  |  |  |  |  |  |  | $ 4,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
B A R D A Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations |  |  |  |  |  |  |  |  |  |  |  | $ 526,000 |  |  |  |  |  |  |  | $ (4,200,000) |  |  |  |
Revenue recognized |  |  |  |  |  |  |  |  |  |  |  | $ 4,600,000 |  |  |  |  |  |  |  |  |  |  |  |
Amendment to Loan and Security Agreement [Member] | UK Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees |  |  | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amendment to Loan and Security Agreement [Member] | Japanese Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees |  | $ 1,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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