| Cover | Nov. 30, 2023 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 30, 2023 |
| Entity File Number | 001-40162 |
| Entity Registrant Name | M3-BRIGADE ACQUISITION II CORP. |
| Entity Central Index Key | 0001839175 |
| Entity Tax Identification Number | 86-1359752 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1700 Broadway |
| Entity Address, Address Line Two | 19th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10019 |
| City Area Code | (212) |
| Local Phone Number | 202-2200 |
| 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-third of one redeemable warrant | |
| Title of 12(b) Security | Units, each consisting of one share of Class A common stock and one-third of one redeemable warrant |
| Trading Symbol | MBAC.U |
| Security Exchange Name | NYSE |
| Class A common stock, par value $0.0001 per share | |
| Title of 12(b) Security | Class A common stock, par value $0.0001 per share |
| Trading Symbol | MBAC |
| Security Exchange Name | NYSE |
| Public warrants, each whole public warrant exercisable for one share of Class A common stock at an exercise price of $11.50 per share | |
| Title of 12(b) Security | Public warrants, each whole public warrant exercisable for one share of Class A common stock at an exercise price of $11.50 per share |
| Trading Symbol | MBAC.WS |
| Security Exchange Name | NYSE |
