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Schedule 2 - Parent Company Financial Statements - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2020 | Sep. 22, 2020 | Jul. 02, 2018
5.000% Senior Notes due September 19, 2022 | Senior Notes | Infinity Property and Casualty Corporation |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |
Stated interest rate, percentage |  |  | 5.00%
Senior Notes, 2.400 Percent Due September 30, 2030 | Senior Notes |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |
Stated interest rate, percentage |  | 2.40% |
Proceeds from debt, net of issuance costs | $ 395.6 |  |
Subsidiary of Common Parent | Non-cash Dividends |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |
Related party transaction, amounts of transaction | $ 106.0 |  |

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