| Pay vs Performance Disclosure - USD ($) | 12 Months Ended |
| Dec. 31, 2022 | Dec. 31, 2021 |
| Pay vs Performance Disclosure [Table] | | |
| Pay vs Performance [Table Text Block] | Year Summary Compensation Table Total for PEO (1)(2) Compensation Actually Paid to PEO (3) Average Summary Compensation Table Total for Non-PEO NEOs (2)(4) Average Compensation Actually Paid to Non-PEO NEOs (3)(4) Total Shareholder Return (5) Net Loss 2022 $ 2,595,395 $ (21,606,202) $ 3,509,439 $ (2,156,954) (5) $ 17.81 $ (128,175) 2021 952,200 (79,705) 3,937,239 3,013,310 (6) 97.19 (83,892) | |
| Named Executive Officers, Footnote [Text Block] | The PEO for each of the periods presented is Mr. Hirsch.The Non-PEO NEOs for 2022 were Dr. Boyle and Dr. Fisher and the Non-PEO NEOs for 2021 were Lauren White, our Chief Financial Officer, and Dr. Fisher. | |
| PEO Total Compensation Amount | $ 2,595,395 | $ 952,200 |
| PEO Actually Paid Compensation Amount | $ (21,606,202) | (79,705) |
| Adjustment To PEO Compensation, Footnote [Text Block] | The dollar amounts reported in these columns represent the amounts of “compensation actually paid.” The amounts are computed in accordance with Item 402(v) of Regulation S-K by deducting and adding the following amounts from the “Total” column of the SCT (pursuant to SEC rules, fair value at each measurement date is computed in a manner consistent with the fair value methodology used to account for share-based payments in our financial statements under GAAP): 2022 2021 PEO Average Non-PEO NEOs PEO Average Non-PEO NEOs Total Compensation from Summary Compensation Table $ 2,595,395 $ 3,509,439 $ 952,200 $ 3,937,239 Adjustments for Equity Awards Adjustments for grant date fair values of equity awards granted in the current year (1,624,400) (2,844,379) — (3,395,354) Year-end fair value of unvested equity awards granted in the current year 284,900 356,546 — 2,172,003 Year-over-year difference of year-end fair values for unvested equity awards granted in prior years (18,018,970) (2,349,947) (3,356,456) (167,996) Fair values at vest date for equity awards granted and vested in current year 158,875 104,252 — 216,575 Difference in fair values between prior year-end fair values and vest date fair values for equity awards granted in prior years (5,002,002) (932,865) 2,324,551 250,843 Total Adjustments for Equity Awards (24,201,597) (5,666,393) (1,031,905) (923,929) Compensation Actually Paid (as calculated) $ (21,606,202) $ (2,156,954) $ (79,705) $ 3,013,310 | |
| Non-PEO NEO Average Total Compensation Amount | $ 3,509,439 | 3,937,239 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ (2,156,954) | 3,013,310 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | The dollar amounts reported in these columns represent the amounts of “compensation actually paid.” The amounts are computed in accordance with Item 402(v) of Regulation S-K by deducting and adding the following amounts from the “Total” column of the SCT (pursuant to SEC rules, fair value at each measurement date is computed in a manner consistent with the fair value methodology used to account for share-based payments in our financial statements under GAAP): 2022 2021 PEO Average Non-PEO NEOs PEO Average Non-PEO NEOs Total Compensation from Summary Compensation Table $ 2,595,395 $ 3,509,439 $ 952,200 $ 3,937,239 Adjustments for Equity Awards Adjustments for grant date fair values of equity awards granted in the current year (1,624,400) (2,844,379) — (3,395,354) Year-end fair value of unvested equity awards granted in the current year 284,900 356,546 — 2,172,003 Year-over-year difference of year-end fair values for unvested equity awards granted in prior years (18,018,970) (2,349,947) (3,356,456) (167,996) Fair values at vest date for equity awards granted and vested in current year 158,875 104,252 — 216,575 Difference in fair values between prior year-end fair values and vest date fair values for equity awards granted in prior years (5,002,002) (932,865) 2,324,551 250,843 Total Adjustments for Equity Awards (24,201,597) (5,666,393) (1,031,905) (923,929) Compensation Actually Paid (as calculated) $ (21,606,202) $ (2,156,954) $ (79,705) $ 3,013,310 | |
| Total Shareholder Return Amount | $ 17.81 | 97.19 |
| Net Income (Loss) | $ (128,175,000) | (83,892,000) |
| PEO Name | Mr. Hirsch. | |
| Additional 402(v) Disclosure [Text Block] | Amounts in this column represent the “Total” column set forth in the Summary Compensation Table, or SCT, which is set forth in this proxy statement on page 33 . See the footnotes to the SCT for further detail regarding the amounts in these columns. Narrative Disclosure: Pay Versus Performance Table The illustrations below provide a graphical description of Compensation Actually Paid, or CAP, (as calculated in accordance with the rules promulgated by the Securities and Exchange Commission, or the SEC) and the following measures: • C4T’s cumulative Total Shareholder Return, or TSR; and • C4T’s Net Income | |
| PEO [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | $ (24,201,597) | (1,031,905) |
| PEO [Member] | Equity Awards Granted During the Year, Grant Date Fair Value Adjustment [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | (1,624,400) | 0 |
| PEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | 284,900 | 0 |
| PEO [Member] | Equity Awards Granted in Prior Years, Unvested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | (18,018,970) | (3,356,456) |
| PEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | 158,875 | 0 |
| PEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | (5,002,002) | 2,324,551 |
| Non-PEO NEO [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | (5,666,393) | (923,929) |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Grant Date Fair Value Adjustment [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | (2,844,379) | (3,395,354) |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | 356,546 | 2,172,003 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Unvested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | (2,349,947) | (167,996) |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | 104,252 | 216,575 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | |
| Pay vs Performance Disclosure [Table] | | |
| Adjustment to Compensation Amount | $ (932,865) | $ 250,843 |
