Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts, life insurance in force	$ 116,697	$ 111,756	$ 108,130
Gross amounts	6,370	5,985	5,681
Ceded amounts to other companies, life insurance in force	39,204	38,281	38,146
Ceded premiums earned	331	290	276
Assumed amounts from other companies, life insurance in force	0	0	0
Assumed amounts from other companies	443	285	199
Net amounts, life insurance in force	77,493	73,475	69,984
Premiums Earned, Net	$ 6,482	$ 5,980	$ 5,604
Percentage of amounts assumed to net, life insurance in force	0.00%	0.00%	0.00%
Percentage of amounts assumed to net	6.80%	4.80%	3.60%
Commercial Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts	$ 3,777	$ 3,578	$ 3,421
Ceded premiums earned	115	109	109
Assumed amounts from other companies	12	7	7
Premiums Earned, Net	$ 3,674	$ 3,476	$ 3,319
Percentage of amounts assumed to net	0.30%	0.20%	0.20%
Personal Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts	$ 1,586	$ 1,503	$ 1,446
Ceded premiums earned	45	41	43
Assumed amounts from other companies	1	1	1
Premiums Earned, Net	$ 1,542	$ 1,463	$ 1,404
Percentage of amounts assumed to net	0.10%	0.10%	0.10%
Excess and Surplus Lines Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts	$ 417	$ 341	$ 292
Ceded premiums earned	19	16	14
Assumed amounts from other companies	0	0	0
Premiums Earned, Net	$ 398	$ 325	$ 278
Percentage of amounts assumed to net	0.00%	0.00%	0.00%
Reinsurance assumed and other non segment
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts	$ 216	$ 201	$ 181
Ceded premiums earned	76	51	39
Assumed amounts from other companies	430	277	191
Premiums Earned, Net	$ 570	$ 427	$ 333
Percentage of amounts assumed to net	75.40%	64.90%	57.40%
Property, Liability and Casualty Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts	$ 5,996	$ 5,623	$ 5,340
Ceded premiums earned	255	217	205
Assumed amounts from other companies	443	285	199
Premiums Earned, Net	$ 6,184	$ 5,691	$ 5,334
Percentage of amounts assumed to net	7.20%	5.00%	3.70%
Life Insurance Segment
SEC Schedule, 12-17, Insurance Companies, Reinsurance
Gross amounts	$ 374	$ 362	$ 341
Ceded premiums earned	76	73	71
Assumed amounts from other companies	0	0	0
Premiums Earned, Net	$ 298	$ 289	$ 270
Percentage of amounts assumed to net	0.00%	0.00%	0.00%