| DEI Document | Dec. 08, 2020 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K/A |
| Document Period End Date | Dec. 8, 2020 |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-37848 |
| Entity Tax Identification Number | 98-0664337 |
| Entity Address, Address Line One | 2035 Maywill Street |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | Richmond |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 23230 |
| City Area Code | 804 |
| Local Phone Number | 289-1300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | true |
| Amendment Description | This Current Report on Form 8-K/A amends the Current Report on Form 8-K filed by Kinsale Capital Group, Inc. (the “Company”) on December 10, 2020, regarding the election of Teresa P. Chia and Robert V. Hatcher, III to the Board of Directors of the Company (the “Board”). At the time of Ms. Chia’s and Mr. Hatcher’s election to the Board, effective January 1, 2021, neither were appointed to serve on any of the Board’s committees. This amendment reports Ms. Chia’s and Mr. Hatcher’s Board committee assignments. |
| Entity Registrant Name | KINSALE CAPITAL GROUP, INC. |
| Title of 12(b) Security | Common Stock, par value $0.01 |
| Trading Symbol | KNSL |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001669162 |
