| Cover | Feb. 27, 2024 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 27, 2024 |
| Entity File Number | 001-41013 |
| Entity Registrant Name | Concord Acquisition Corp III |
| Entity Central Index Key | 0001851961 |
| Entity Tax Identification Number | 86-2171699 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 477 Madison Avenue |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10022 |
| City Area Code | 212 |
| Local Phone Number | 883-4330 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
| Units, each consisting of one share of Class A Common Stock and one-half of one Warrant [Member] | |
| Title of 12(b) Security | Units, each consisting of one share of Class A Common Stock and one-half of one Warrant |
| Trading Symbol | CNDB.U |
| Security Exchange Name | NYSE |
| Common Stock [Member] | |
| Title of 12(b) Security | Class A Common Stock, par value $0.0001 per share |
| Trading Symbol | CNDB |
| Security Exchange Name | NYSE |
| Warrant [Member] | |
| Title of 12(b) Security | Warrants, each whole warrant exercisable for one share of Class A Common Stock at an exercise price of $11.50 |
| Trading Symbol | CNDB.WS |
| Security Exchange Name | NYSE |
