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Liquidity (Details) |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 4 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
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 | Aug. 31, 2019 $ / shares | Jun. 30, 2019 USD ($) shares | Mar. 31, 2019 USD ($) shares | Jun. 30, 2018 USD ($) shares | Mar. 31, 2018 USD ($) shares | Dec. 31, 2018 USD ($) shares | Jun. 30, 2019 USD ($) shares | Jun. 30, 2018 USD ($) | May 24, 2018 shares | Dec. 31, 2017 USD ($)
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss from continuing operations |  |  |  |  |  |  |  |  | $ 2,267,000 |  | $ 2,285,000 |  |  | $ 4,729,000 | $ 5,472,000 |  |
Accumulated deficit |  |  |  |  |  |  |  |  | (426,680,000) |  |  |  | $ (414,383,000) | $ (426,680,000) |  |  |
Substantial doubt about going concern, description |  |  |  |  |  |  |  |  |  |  |  |  |  | These factors raise substantial doubt about our ability to continue as a going concern. |  |  |
Cash and cash equivalents |  |  |  |  |  |  |  |  | 4,530,000 |  |  |  | 5,261,000 | $ 4,530,000 |  |  |
Minimum cash/cash equivalents covenant |  |  |  |  |  |  |  |  | 2,000,000 |  |  |  |  | 2,000,000 |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,984,000 | (200,000) |  |
Common stock issued (in shares) | shares |  |  |  |  | 6,723 |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  |  |  | 23,400,000 |  |  |  |  |  |  |  |  | 2,300,000 |
Proceeds from issuance warrants |  |  |  |  | $ 5,700,000 |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split of common stock |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |  |  |  |
Stockholders’ equity (deficit) |  |  |  |  |  |  |  |  | (6,276,000) | $ 3,857,000 | 4,751,000 | $ 8,480,000 | 5,225,000 | (6,276,000) | 4,751,000 |  | $ 13,000,000
Common stock issued, value |  |  |  |  |  |  |  |  | 64,000 | $ 1,873,000 | $ (297,000) | $ 27,000 |  |  |  |  |
Cash proceeds from sale of subsidiary |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,789,000 | $ 0 |  |
UK Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary |  | $ 3,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
UK Subsidiary and Cell Therapy Assets [Member] | Amendment to Loan and Security Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees |  | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Japanese Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary | $ 2,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Japanese Subsidiary and Cell Therapy Assets [Member] | Amendment to Loan and Security Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees | $ 1,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Nasdaq Stock Market LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |  |  |
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) |  |  |  |  |  |  |  |  | (6,300,000) |  |  |  |  | (6,300,000) |  |  |
Minimum stockholders equity requirement |  |  |  |  |  |  |  |  | $ 2,500,000 |  |  |  |  | $ 2,500,000 |  |  |
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. |  |  |
Nasdaq Stock Market LLC [Member] | Forecast [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split of common stock |  |  |  |  |  |  |  | 0.02 |  |  |  |  |  |  |  |  |
Minimum bid price of common stock required for Nasdaq listing rule | $ / shares |  |  |  |  |  |  |  | $ 1.00 |  |  |  |  |  |  |  |  |
Series C Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of convertible shares converted into common stock (in shares) | shares |  |  |  |  | 200,000 |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  | 7,059,150 |  |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) | shares |  |  |  |  | 6,723 |  |  |  | 5,000 | 139,855 | 192 | 202 |  |  |  |  |
Number of shares callable by warrants (in shares) | shares |  |  |  |  | 141,183 |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercise price (in dollars per share) | $ / shares |  |  |  |  | $ 39.93 |  |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | Series C Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of convertible shares converted into common stock (in shares) | shares |  |  |  |  |  |  |  |  |  | 1,653 |  |  |  |  |  |  |
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining availability under financing facility |  |  |  |  |  |  |  |  | $ 0 |  |  |  |  | $ 0 |  |  |
Common Stock [Member] | Lincoln Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  |  |  |  |  | $ 300,000 | $ 100,000 |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  | 12,802 | 5,000 |  |  |
Common stock issued, value |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period exercisable from the date of issuance |  |  | 24 months |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrestricted cash and cash equivalents |  |  |  |  |  |  |  |  | 2,000,000 |  |  |  |  | $ 2,000,000 |  |  |
Maximum [Member] | Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  | $ 6,500,000 |  |  |  |  |  |  |  |  |  |  |
Maximum [Member] | Common Stock [Member] | Lincoln Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining availability under financing facility |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |  | $ 100,000 |  |  |

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