| Cover | Jul. 28, 2022 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 28, 2022 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 001-39484 |
| Entity Registrant Name | METROMILE, INC. |
| Entity Central Index Key | 0001819035 |
| Entity Tax Identification Number | 84-4916134 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 425 Market Street #700 |
| Entity Address, City or Town | San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94105 |
| City Area Code | 888 |
| Local Phone Number | 242-5204 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | MILE |
| Security Exchange Name | NASDAQ |
| Warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 per share | |
| 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 | MILEW |
| Security Exchange Name | NASDAQ |
