| Document and Entity Information | Feb. 08, 2022 |
| Document And Entity Information [Line Items] | |
| Document Type | 8-K/A |
| Amendment Flag | true |
| Document Period End Date | Feb. 8, 2022 |
| Entity Registrant Name | QUANERGY SYSTEMS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39222 |
| Entity Tax Identification Number | 88-0535845 |
| Entity Address, Address Line One | 433 Lakeside Drive |
| Entity Address, City or Town | Sunnyvale |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94085 |
| City Area Code | 408 |
| Local Phone Number | 245-9500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Description | On February 8, 2022, Quanergy Systems, Inc., a Delaware corporation (the “Company”) (f/k/a CITIC Capital Acquisition Corp. (“CCAC”)), filed a Current Report on Form 8-K and Amendment No. 1 on Form 8-K/A (together, the “Original Report”) to report the Closing and related matters under Items 1.01, 2.01, 3.02, 4.01, 5.01, 5.02, 5.06 and 9.01 of Form 8-K. On March 31, 2022, the Company filed Amendment No. 2 on Form 8-K/A to amend the financial statements provided under Items 9.01(a) and 9.01(b) in the Original Report to include (a) the audited consolidated financial statements of Legacy Quanergy as of and for the years ended December 31, 2021 and 2020 and the related notes and (b) the unaudited pro forma condensed combined financial information of the Company as of and for the year ended December 31, 2021.This Amendment No. 3 amends the disclosure provided under Item 4.01 in the Original Report to confirm that, upon the Company’s filing of the 2021 Form 10-K on March 31, 2022, WithumSmith+Brown, PC was dismissed as, and Grant Thornton LLP became, the Company’s independent registered public accounting firm. This Amendment No. 3 does not amend any other item of the Original Report or purport to provide an update or a discussion of any developments at the Company subsequent to the filing date of the Original Report. |
| Entity Central Index Key | 0001794621 |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | QNGY |
| Security Exchange Name | NYSE |
| Warrant [Member] | |
| Document And Entity Information [Line Items] | |
| Title of 12(b) Security | Warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 per share |
| Trading Symbol | QNGY WT |
| Security Exchange Name | NYSE |
