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Fair value of asset after deduction of liability.

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Fair Value Measurement (Narrative) (Details)	3 Months Ended		9 Months Ended
Fair Value Measurement (Narrative) (Details)	Sep. 30, 2023 USD ($) subsidiary	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) subsidiary	Sep. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Credit Derivatives [Line Items]
Goodwill impairment	$ 44,110,000	$ 0	$ 44,110,000	$ 0
Number of proassurance's insurance subsidiaries \| subsidiary	3		3
Fair value of funded deferred compensation assets	$ 29,700,000		$ 29,700,000			$ 27,900,000
Workers' Compensation Insurance Reporting Unit
Credit Derivatives [Line Items]
Goodwill, fair value					$ 44,100,000
Goodwill impairment	44,100,000		44,110,000
Fair Value
Credit Derivatives [Line Items]
Deferred compensation liabilities	29,400,000		29,400,000			27,900,000
Fair Value, Nonrecurring
Credit Derivatives [Line Items]
Fair value, net asset (liability)	$ 0		$ 0			$ 0