Reinsurance and Indemnification - Michigan catastrophic claims association (Details) - USD ($)		6 Months Ended	12 Months Ended	24 Months Ended
	Jul. 01, 2023	Jun. 30, 2022	Dec. 31, 2022	Jun. 30, 2023	Jun. 30, 2021	Dec. 31, 2021	Nov. 03, 2021
Reinsurance Retention Policy [Line Items]
Assets			$ 97,957,000,000			$ 99,440,000,000
Retained income			50,954,000,000			53,294,000,000
Michigan Catastrophic Claim Association
Reinsurance Retention Policy [Line Items]
Reinsurance and indemnification recoverables, net			6,720,000,000			$ 6,700,000,000
Program funding, per vehicle annual assessment			$ 86
Reinsurance increase, percentage			6.00%
Retention level per claim					$ 580,000
Term of catastrophe reinsurance agreement contract					2 years
Assets		$ 21,820,000,000
Retained income		3,680,000,000
Retained earnings accumulated deficit decrease		$ 44,890,000,000
Program surplus, per vehicle refund							$ 400
Program surplus, per historical vehicle refund							$ 80
Michigan Catastrophic Claim Association | Forecast
Reinsurance Retention Policy [Line Items]
Retention level per claim				$ 600,000
Term of catastrophe reinsurance agreement contract				2 years
Program funding, additional per vehicle annual assessment	$ 48