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v3.20.1

Organization and Operations - Additional Information (Details) |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |  |
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Aug. 05, 2019 $ / shares shares | Apr. 25, 2019 USD ($) | Apr. 24, 2019 USD ($) | Sep. 21, 2018 USD ($) | Aug. 28, 2018 $ / shares | Jul. 25, 2018 USD ($) shares | Jun. 01, 2018 USD ($) | May 23, 2018 $ / shares shares | Sep. 30, 2019 $ / shares shares | Aug. 31, 2019 $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2019 USD ($) Subsidiary $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Aug. 16, 2019 shares | Aug. 06, 2019 shares | Jun. 30, 2019 USD ($) | May 24, 2018 shares | Dec. 31, 2017 USD ($) shares
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of wholly-owned subsidiaries | Subsidiary |  |  |  |  |  |  |  |  |  |  |  | 5 |  |  |  |  |  |
Proceeds from sale of business | $ |  |  |  |  |  |  |  |  |  |  |  | $ 5,637,000 | $ 0 |  |  |  |  |
Reverse stock split of common stock | 0.02 |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares | $ 0.001 |  |  |  |  |  |  | $ 0.001 |  |  | $ 0.001 | $ 0.001 | $ 0.001 |  |  |  |  |
Common stock, shares authorized (in shares) |  |  |  |  |  |  |  | 75,000,000 |  |  | 100,000,000 | 100,000,000 | 100,000,000 |  |  |  | 100,000,000 |
Common stock, shares issued (in shares) |  |  |  |  |  |  |  | 61,600,000 |  |  | 296,609 | 3,880,588 | 296,609 |  |  |  | 6,200,000 |
Common stock, shares outstanding (in shares) |  |  |  |  |  |  |  | 61,600,000 |  |  | 296,609 | 3,880,588 | 296,609 |  |  |  | 6,200,000 |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  | 23,400,000 |  |  |  |  |  |  |  |  | 2,300,000 |
Preferred stock, shares authorized (in shares) | 5,000,000 |  |  |  |  |  |  | 5,000,000 |  |  | 5,000,000 | 5,000,000 | 5,000,000 |  | 5,000,000 |  | 5,000,000 |
Common stock, reverse stock split, fractional shares issued | 0 |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |
Reverse stock split effective date for trading purposes | Aug. 06, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split of common stock description |  |  |  |  |  |  |  |  |  |  |  | Upon effectiveness, each 50 shares of issued and outstanding common stock were converted into one newly issued and outstanding share of common stock. |  |  |  |  |  |
Net loss | $ |  |  |  |  |  |  |  |  |  |  |  | $ 10,887,000 | $ 12,634,000 |  |  |  |  |
Accumulated deficit | $ |  |  |  |  |  |  |  |  |  |  | $ (414,383,000) | (425,270,000) | (414,383,000) |  |  |  |  |
Net cash used in operating activities | $ |  |  |  |  |  |  |  |  |  |  |  | $ (5,906,000) | (11,975,000) |  |  |  |  |
Substantial doubt about going concern, description |  |  |  |  |  |  |  |  |  |  |  | These factors raise substantial doubt about the Company’s ability to continue as a going concern |  |  |  |  |  |
Reimbursement revenue recognized | $ |  |  |  |  |  |  |  |  |  |  |  | $ 4,600,000 |  |  |  |  |  |
Option vesting period |  |  |  |  |  |  |  |  |  |  |  | 4 years |  |  |  |  |  |
Option granted |  |  |  |  |  |  |  |  |  |  |  | 2,800 |  |  |  |  |  |
Common stock issued, value | $ |  |  |  |  |  |  |  |  |  |  |  | $ 2,208,000 | 1,624,000 |  |  |  |  |
Proceeds from sale of common stock, net | $ |  |  |  |  |  |  |  |  |  |  |  | 15,964,000 | 0 |  |  |  |  |
Proceeds from issuance warrants | $ |  |  |  |  |  | $ 5,700,000 |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' equity (deficit) | $ |  |  |  |  |  |  |  |  |  |  | $ 5,225,000 | $ 1,160,000 | $ 5,225,000 |  |  |  |  | $ 13,000,000
Nasdaq Stock Market LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [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 |  |  |  |  |  |  |  |  |  |  |  |  |
Description of compliance with minimum bid price requirement |  |  |  |  |  |  |  |  |  |  |  | The Company was 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 |  |  |  |  |  |  |  |  |  | 786,807 |  |  |  |  |  |  |  |
Stockholders' equity (deficit) | $ |  |  |  |  |  |  |  |  |  |  |  | $ (1,200,000) |  |  |  | $ 6,300,000 |  |
Minimum stockholders equity requirement | $ |  |  |  |  |  |  |  |  |  |  |  | $ 2,500,000 |  |  |  |  |  |
Minimum shares requirement for continued listing |  |  |  |  |  |  |  |  |  |  |  |  |  | 500,000 |  |  |  |
Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  |  |  |  |  |  |  | 3,450,000 |  |  |  |  |  |
Sale of Stock, Price Per Share | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 5.00 |  |  |  |  |  |
Representative Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  |  |  |  |  | 75,000 |  |  |  |  |  |
Warrant exercise price (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 6.25 |  |  |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  |  |  |  |  |  |  |  |  | 296,609 | 3,880,588 | 296,609 |  |  |  |  | 115,651
Common stock issued (in shares) |  |  |  |  |  | 6,723 |  |  |  |  |  | 184,666 | 92,169 |  |  |  |  |
Warrant exercised |  |  |  |  |  |  |  |  |  |  |  | 65,114 |  |  |  |  |  |
Stockholders' equity (deficit) | $ |  |  |  |  |  |  |  |  |  |  |  | $ 4,000 |  |  |  |  |  |
Common Stock [Member] | Lincoln Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  |  |  |  |  |  | 12,802 | 32,170 |  |  |  |  |  |
Common stock issued, value | $ |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period exercisable from the date of issuance |  |  |  | 24 months |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net | $ |  |  |  |  |  |  |  |  |  |  | $ 300,000 | $ 300,000 |  |  |  |  |  |
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining availability under financing facility | $ |  |  |  |  |  |  | $ 0 |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | Maximum [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net | $ |  |  |  |  |  |  | $ 6,500,000 |  |  |  |  |  |  |  |  |  |  |
Common Class A [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  |  |  |  |  |  |  | 289,000 |  |  |  |  |  |
Common Class B [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  |  |  |  |  | 2,711,000 |  |  |  |  |  |
Series C Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares authorized (in shares) |  |  |  |  |  | 7,000 |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  | 6,723 |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued, value | $ |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,041,000 |  |  |  |  |
Underwriter [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [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 |  |  |  |  |  |  |  |  | 450,000 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Option granted |  |  |  |  |  |  |  |  | 450,000 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercised |  |  |  |  |  |  |  |  | 450,000 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Representative Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  |  | 75,000 |  |  |  |  |  |  |  |  |
Warrant exercise price (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  | $ 6.25 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Common Class A [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  | $ 0.001 |  |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  |  |  |  | 289,000 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Common Class A [Member] | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of Stock, Price Per Share | $ / shares |  |  |  |  |  |  |  |  | $ 5.00 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Common Class B [Member] | Series V Warrants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  |  | 2,711,000 |  |  |  |  |  |  |  |  |
Underwriter [Member] | Common Class B [Member] | Series U Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of Stock, Price Per Share | $ / shares |  |  |  |  |  |  |  |  | $ 4.9999 |  |  |  |  |  |  |  |  |
2014 Equity Incentive Plan [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  | 9,100,000 |  |  |  |  |  |  |  |  | 900,000 |
Sale of UK Subsidiary and Certain Assets [Member] | Loan and Security Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of business | $ |  |  | $ 4,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees | $ |  |  | 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of the Japanese Subsidiary and Certain Assets [Member] | Loan and Security Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of business | $ |  | $ 3,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees | $ |  | 1,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
UK Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of business | $ |  |  | 3,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
UK Subsidiary and Cell Therapy Assets [Member] | Amendment To Loan And Security Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees | $ |  |  | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Japanese Subsidiary and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of business | $ |  | 2,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Japanese Subsidiary and Cell Therapy Assets [Member] | Amendment To Loan And Security Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis Of Presentation And New Accounting Standards [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees | $ |  | $ 1,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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