| Cover | Aug. 29, 2023 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 29, 2023 |
| Entity File Number | 001-40120 |
| Entity Registrant Name | Fusion Acquisition Corp. II |
| Entity Central Index Key | 0001840225 |
| Entity Tax Identification Number | 86-1352058 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 667 Madison Avenue |
| Entity Address, Address Line Two | 5th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10065 |
| City Area Code | 212 |
| Local Phone Number | 763-0169 |
| 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 | FSNB.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 | FSNB |
| Security Exchange Name | NYSE |
| Redeemable warrants, each whole warrant exercisable for one share of Class A common stock, each at an exercise price of $11.50 per share | |
| Title of 12(b) Security | Redeemable warrants, each whole warrant exercisable for one share of Class A common stock, each at an exercise price of $11.50 per share |
| Trading Symbol | FSNB WS |
