Income Taxes (Significant components of the Company's deferred tax assets and liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Deferred Tax Assets:
Property and casualty claim and claim adjustment expense reserves	$ 276	$ 234
Unearned premium reserves	227	225
Deferred non-insurance warranty revenue	53	59
Employee benefits	7	13
Deferred retroactive reinsurance benefit	99	89
Net unrealized losses	258	494
Other assets	101	107
Gross deferred tax assets	1,021	1,221
Deferred Tax Liabilities:
Investment valuation differences	168	130
Deferred acquisition costs	143	140
Policyholder reserves	25	48
Software and hardware	57	17
Other liabilities	53	36
Gross deferred tax liabilities	446	371
Net deferred tax asset	$ 575	$ 850