Insurance Company Subsidiary Operations - Effects of Reinsurance on Premiums Written and Earned (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Written
Net premiums	$ 85	$ 79
Earned
Net premiums	83	77
WNFIC
Written
Direct premiums	1,078	1,005
Ceded premiums	(1,078)	(1,005)
Earned
Direct premiums	1,044	946
Ceded premiums	(1,044)	(946)
Captive
Written
Direct premiums	656
Assumed premiums	180	153
Ceded premiums	(751)	(74)
Net premiums	85	79
Earned
Direct premiums	1,023
Assumed premiums	120	151
Ceded premiums	(1,060)	(74)
Net premiums	$ 83	$ 77