SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Condensed Statements of Cash Flows (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Interest paid, affiliates	$ 1.0	$ 0.8	$ 0.8
State Auto Financial
Condensed Financial Statements, Captions [Line Items]
Interest paid, affiliates	$ 6.3	$ 6.1	$ 6.1

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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