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Stockholders' Equity - Preferred Stock (Details) - $ / shares |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Sep. 21, 2021 | Sep. 20, 2021 | Mar. 31, 2022 | Dec. 31, 2020 | Dec. 31, 2021
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares authorized (in shares) |  |  | 5,000,000 |  | 5,000,000
Preferred stock, par value (in dollars per share) |  |  | $ 0.001 |  | $ 0.001
Preferred stock, shares outstanding (in shares) |  |  | 1,952 |  | 1,952
Series A Convertible Preferred Stock [Member] |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares outstanding (in shares) |  | 0 |  | 0 |
Convertible preferred stock |  | 3.60% |  | 3.60% |
Series A 3.6% Convertible preferred stock eliminated date | Sep. 21, 2021 |  |  |  |
Series B Convertible Preferred Stock [Member] |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares outstanding (in shares) |  |  | 1,014 |  | 1,014
Series B Convertible Preferred Stock [Member] | 2018 Rights Offering [Member] |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares outstanding (in shares) |  |  | 1,014 |  |
Number of preferred stock, shares converted |  |  | 5,978 |  |
Series C Convertible Preferred Stock [Member] |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares outstanding (in shares) |  |  | 938 |  | 938
Series C Convertible Preferred Stock [Member] | 2018 Rights Offering [Member] |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares outstanding (in shares) |  |  | 938 |  |
Number of preferred stock, shares converted |  |  | 416,889 |  |

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- Definition The percentage rate used to calculate dividend payments on preferred stock. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644 + Details
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- Definition Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644 + Details
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