Notes Payable (Schedule of Long-term Debt) (Details)			3 Months Ended	12 Months Ended
Notes Payable (Schedule of Long-term Debt) (Details)	May 01, 2025 USD ($)	Nov. 22, 2024	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Nov. 30, 2023 USD ($)	Nov. 18, 2022 USD ($)	Mar. 31, 2021 USD ($)	Mar. 08, 2017 USD ($)
Debt Instrument [Line Items]
Interest rate (in percent)								4.40%
Total principal amount			$ 575,000,000	$ 575,000,000
Less unamortized discount and debt issuance costs			773,000	872,000
Notes payable			574,227,000	574,128,000
Debt issuance cost								$ 3,400,000
Debt instrument, discount percent								99.847%
Effective interest rate								4.45%
Unamortized debt issuance cost			600,000
Unsecured Notes Two \| Revolving Credit Facility
Debt Instrument [Line Items]
Loan maximum borrowing capacity					$ 250,000,000	$ 200,000,000	$ 75,000,000
Drawn down amount under credit facility			200,000,000	200,000,000
Unsecured Notes Two \| Revolving Credit Facility \| Consolidated Insurance Subsidiary
Debt Instrument [Line Items]
Drawn down amount under credit facility contributed			150,000,000
Unsecured Notes Two \| Revolving Credit Facility \| Subsequent Event
Debt Instrument [Line Items]
Effective interest rate	5.65%
Drawn down amount under credit facility	$ 200,000,000
Remaining amount available to be drawn	$ 50,000,000
Unsecured notes
Debt Instrument [Line Items]
Notes payable			$ 374,227,000	374,128,000
Unsecured notes \| Notes payable \| Level 2 \| Unsecured Notes One
Debt Instrument [Line Items]
Interest rate (in percent)			4.40%
Unsecured debt			$ 375,000,000	375,000,000				$ 375,000,000
Unsecured notes \| Notes payable \| Level 2 \| Unsecured Notes Two
Debt Instrument [Line Items]
Unsecured debt			$ 200,000,000	$ 200,000,000
Minimum \| Unsecured Notes Two \| Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			1.125%
Debt to total capital ratio		0.20
Commitment fee on undrawn portion of facility		0.125%	0.15%
Minimum \| Unsecured notes \| Notes payable \| Level 2 \| Unsecured Notes Two
Debt Instrument [Line Items]
Basis spread on variable rate			1.125%
Maximum \| Unsecured Notes Two \| Revolving Credit Facility
Debt Instrument [Line Items]
Debt to total capital ratio		0.30	0.240
Commitment fee on undrawn portion of facility		0.225%
Maximum \| Unsecured notes \| Notes payable \| Level 2 \| Unsecured Notes Two
Debt Instrument [Line Items]
Basis spread on variable rate			1.50%

MERCURY GENERAL CORP 10-Q