Cover
| Cover | Nov. 04, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 4, 2021 |
| Entity File Number | 001-38971 |
| Entity Registrant Name | XL FLEET CORP. |
| Entity Central Index Key | 0001772720 |
| Entity Tax Identification Number | 83-4109918 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 145 Newton Street |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02135 |
| City Area Code | (617) |
| Local Phone Number | 718-0329 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | XL |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |