Schedule V - Supplemental Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Supplemental Information Concerning Property and Casualty Insurance Operations [Abstract]
Deferred acquisition costs	$ 737	$ 708
Reserves for unpaid claim and claim adjustment expenses	24,174	22,706
Discount deducted from claim and claim adjustment expense reserves above (based on interest rates ranging from 3.5% to 6.5%)	1,146	1,209
Unearned premiums	5,761	5,119
Net written premiums	8,405	8,059	$ 7,656
Net earned premiums	8,175	7,649	7,428
Net investment income	2,111	1,896	2,063
Incurred claim and claim adjustment expenses related to current year	5,970	5,793	5,356
Incurred claim and claim adjustment expenses related to prior years	(104)	(119)	(127)
Amortization of deferred acquisition costs	1,443	1,410	1,383
Paid claim and claim adjustment expenses	$ 4,844	$ 5,164	$ 5,576
Minimum
Supplemental Information Concerning Property and Casualty Insurance Operations [Abstract]
Interest rate at which discount computed	3.50%	3.50%
Maximum
Supplemental Information Concerning Property and Casualty Insurance Operations [Abstract]
Interest rate at which discount computed	6.40%	6.40%