Reinsurance and Indemnification - Michigan Catastrophic Claims Association (Narrative) (Details) - USD ($)		6 Months Ended	12 Months Ended	24 Months Ended
	Jul. 01, 2023	Jun. 30, 2023	Dec. 31, 2023	Jun. 30, 2025	Jun. 30, 2023	Dec. 31, 2022
Reinsurance Retention Policy [Line Items]
Assets			$ 103,362,000,000			$ 97,989,000,000
Retained income			49,716,000,000			50,970,000,000
Michigan Catastrophic Claim Association
Reinsurance Retention Policy [Line Items]
Reinsurance and indemnification recoverables, net			6,420,000,000			$ 6,720,000,000
Program funding, per vehicle annual assessment			$ 122
Reinsurance increase, percentage			6.00%
Retention level per claim					$ 600,000
Term of catastrophe reinsurance agreement contract					2 years
Assets		$ 21,580,000,000			$ 21,580,000,000
Retained income		2,050,000,000.00			$ 2,050,000,000.00
Retained earnings accumulated deficit decrease		$ 44,950,000,000
Program funding, additional per vehicle annual assessment	$ 48
Michigan Catastrophic Claim Association | Forecast
Reinsurance Retention Policy [Line Items]
Retention level per claim				$ 635,000
Term of catastrophe reinsurance agreement contract				2 years
Other PIP Coverage
Reinsurance Retention Policy [Line Items]
Program funding, per vehicle annual assessment			$ 48