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Liquidity (Details) - USD ($) |  |  |  |  |  |  |  |  | 3 Months Ended | 7 Months Ended | 10 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 25, 2019 | Apr. 24, 2019 | Sep. 21, 2018 | Aug. 28, 2018 | Jul. 25, 2018 | Jun. 01, 2018 | Nov. 28, 2017 | Sep. 05, 2017 | Mar. 31, 2019 | Dec. 31, 2018 | Mar. 31, 2018 | Dec. 31, 2018 | Mar. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | May 24, 2018 | May 23, 2018 | Dec. 31, 2016
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  |  |  |  |  |  |  | $ 3,150,000 |  | $ 4,409,000 |  |  | $ 12,634,000 | $ 22,686,000 |  |  |
Accumulated deficit |  |  |  |  |  |  |  |  | (417,533,000) | $ (414,383,000) |  | $ (414,383,000) | $ (417,533,000) | (414,383,000) | (401,749,000) |  |  |
Net cash used in operating activities |  |  |  |  |  |  |  |  | $ (3,270,000) |  | (4,119,000) |  |  | $ (11,975,000) | (18,128,000) |  |  |
Substantial doubt about going concern, description |  |  |  |  |  |  |  |  | These factors raise substantial doubt about the Company’s ability to continue as a going concern. |  |  |  |  | These factors raise substantial doubt about the Company’s ability to continue as a going concern |  |  |  |
Cash and cash equivalents |  |  |  |  |  |  |  |  | $ 3,872,000 | 5,261,000 |  | 5,261,000 | 3,872,000 | $ 5,261,000 | 9,550,000 |  |  | $ 12,600,000
Minimum cash/cash equivalents covenant |  |  |  |  |  |  |  |  | 2,000,000 | 2,000,000 |  | 2,000,000 | 2,000,000 | 2,000,000 |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  | 1,919,000 |  | (150,000) |  |  | 0 | 0 |  |  |
Common stock issued (in shares) |  |  |  |  | 6,723 |  | 10,000 |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,300,000 | 23,400,000 |
Proceeds from issuance warrants |  |  |  |  | $ 5,700,000 |  | $ 8,800,000 |  |  |  |  |  |  |  |  |  |  |
Common stock issued, value |  |  |  |  |  |  |  |  | $ 1,873,000 |  | $ 27,000 |  |  | $ 1,624,000 | $ 12,716,000 |  |  |
Subsequent Event [Member] | Cytori Ltd. and Cell Therapy Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary |  | $ 3,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Member] | Cytori Ltd. and Cell Therapy Assets [Member] | Amendment to Loan and Security Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for principal, interest and fees |  | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Member] | Cytori Therapeutics, K.K. and Cell Therapy Assets used in Japan [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds from sale of subsidiary | $ 2,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Member] | Cytori Therapeutics, K.K. and Cell Therapy Assets used in Japan [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 |  |  |  | 30 days |  |  |  |  |  |  |  |  |  |
Minimum bid price of common stock required for Nasdaq listing rule |  |  |  | $ 1.00 |  |  |  | $ 1.00 |  |  |  |  |  |  |  |  |  |
Grace period provided with minimum bid price for Nasdaq listing rule |  |  |  | 180 days |  |  |  | 180 days |  |  |  |  |  |  |  |  |  |
Grace date for minimum bid price requirement for Nasdaq listing |  |  |  | Feb. 25, 2019 |  |  |  | Mar. 05, 2018 |  |  |  |  |  |  |  |  |  |
Common stock minimum bid price required to regain compliance |  |  |  | $ 1.00 |  |  |  | $ 1.00 |  |  |  |  |  |  |  |  |  |
Number of consecutive business days required to regain compliance |  |  |  | 10 days |  |  |  | 10 days |  |  |  |  |  |  |  |  |  |
Date to regain compliance after meeting continued listing requirement |  |  |  | Aug. 26, 2019 |  |  |  | Sep. 04, 2018 |  |  |  |  |  |  |  |  |  |
Additional grace period provided with minimum bid price to regain compliance |  |  |  | 180 days |  |  |  | 180 days |  |  |  |  |  |  |  |  |  |
Description of compliance with minimum bid price requirement |  |  |  | We were 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. |  |  |  |  |  |  |  |  |  | We were 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. |  |  |  |
Series C Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of convertible shares converted into common stock (in shares) |  |  |  |  | 168,478 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  | 7,059,150 |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued, value |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,041,000 |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  | 6,723 |  | 10,000 |  | 139,855 |  | 201 |  |  | 92,169 | 24,474 |  |  |
Number of shares callable by warrants (in shares) |  |  |  |  | 50 |  | 36,000 |  |  |  |  |  |  |  |  |  |  |
Warrant exercise price (in dollars per share) |  |  |  |  | $ 39.93 |  | $ 166.65 |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | Series C Convertible Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of convertible shares converted into common stock (in shares) |  |  |  |  |  |  |  |  | 1,652 |  |  |  |  | 80,868 |  |  |  |
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  |  |  |  | $ 1,700,000 | $ 3,800,000 |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  |  |  |  |  |  |  | 1,584 | 200,000 |  |  |  |  |
Common Stock [Member] | Lincoln Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of common stock, net |  |  |  |  |  |  |  |  |  | $ 300,000 |  |  |  |  |  |  |  |
Common stock issued (in shares) |  |  |  |  |  |  |  |  | 0 | 12,802 |  |  |  |  |  |  |  |
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 |  | $ 2,000,000 | $ 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 |  |  |  |  |  |  |  |  |  |  |  |

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