| Document and Entity Information | Mar. 11, 2021 |
| Entity Listings [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 11, 2021 |
| Entity Registrant Name | Protective Insurance Corp |
| Entity Incorporation, State or Country Code | IN |
| Entity File Number | 0-05534 |
| Entity Tax Identification Number | 35-0160330 |
| Entity Address, Address Line One | 111 Congressional Boulevard |
| Entity Address, City or Town | Carmel |
| Entity Address, State or Province | IN |
| Entity Address, Postal Zip Code | 46032 |
| City Area Code | 317 |
| Local Phone Number | 452-7426 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000009346 |
| Common Class A [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Class A Common Stock, No Par Value |
| Trading Symbol | PTVCA |
| Security Exchange Name | NASDAQ |
| Common Class B [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Class B Common Stock, No Par Value |
| Trading Symbol | PTVCB |
| Security Exchange Name | NASDAQ |
