Reserve for Property and Casualty Insurance Claims and Claims Expense - Rollforward of the reserve for property and casualty insurance claims and claims expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Incurred claims and claims expense related to:
Prior years	$ 145	$ (241)
National General
Activity in the reserve for property-liability insurance claims and claims expense:
National General acquisition as of January 4, 2021	0	1,797
Property-Liability
Activity in the reserve for property-liability insurance claims and claims expense:
Balance as of January 1	33,060	27,610
Less recoverables	(9,479)	(7,033)
Net balance as of January 1	23,581	20,577
Incurred claims and claims expense related to:
Current year	7,677	6,284
Prior years	145	(241)
Total incurred	7,822	6,043
Claims and claims expense paid related to:
Current year	(2,751)	(2,541)
Prior years	(4,735)	(3,731)
Total paid	(7,486)	(6,272)
Net balance as of March 31	23,917	22,145
Plus recoverables	9,074	9,269
Balance as of March 31	$ 32,991	$ 31,414