| Document And Entity Information | 12 Months Ended |
| Dec. 31, 2022 | |
| Document Information Line Items | |
| Entity Registrant Name | CEPTON, INC. |
| Document Type | POS AM |
| Amendment Flag | true |
| Amendment Description | The original registration statement (the “Existing Registration Statement”) of Cepton, Inc. (“Cepton”) on Form S-1 (File No. 333-262667), declared effective by the Securities and Exchange Commission (the “SEC”) on May 11, 2022, to which this Registration Statement is Post-Effective Amendment No. 1 (this “Registration Statement”), covered the issuance and sale of up to 14,700,000 shares of our common stock.This Registration Statement constitutes Post-Effective Amendment No. 1 to the Existing Registration Statement and is being filed to convert such registration statement on Form S-1 into a registration statement on Form S-3 because Cepton is now eligible to use Form S-3. This Registration Statement contains an updated prospectus relating to the offering and sale of the shares of outstanding common stock covered by the Existing Registration Statement. This Registration Statement amends and restates the information contained in the Existing Registration Statement (and all amendments and supplements thereto) under the headings contained herein.All filing fees payable in connection with the registration of the shares of our common stock covered by this Registration Statement were paid by the Registrant at the time of the initial filing of the Existing Registration Statement. No additional securities are registered hereby. |
| Entity Central Index Key | 0001498233 |
| Entity Filer Category | Non-accelerated Filer |
| Entity Small Business | true |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Incorporation, State or Country Code | DE |
