Schedule IV - Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reinsurance Face Amount/Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 4,123,019	$ 3,985,589	$ 3,733,997
Ceded to Other Companies	862,460	791,354	767,499
Assumed from Other Companies	188,576	197,343	207,083
Net Amount	$ 3,449,135	$ 3,391,578	$ 3,173,581
Percentage of Amount Assumed to Net	5.50%	5.80%	6.50%
Gross Amount	$ 33,260	$ 35,048	$ 31,797
Ceded to Other Companies	2,080	1,843	1,811
Assumed from Other Companies	3,022	2,574	2,105
Premiums	$ 34,202	$ 35,779	$ 32,091
Percentage of Amount Assumed to Net	8.80%	7.20%	6.60%
Life Insurance
Reinsurance Face Amount/Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 30,333	$ 32,248	$ 29,035
Ceded to Other Companies	1,990	1,792	1,761
Assumed from Other Companies	3,022	2,574	2,105
Premiums	$ 31,365	$ 33,030	$ 29,379
Percentage of Amount Assumed to Net	9.60%	7.80%	7.20%
Accident and Health Insurance
Reinsurance Face Amount/Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 2,927	$ 2,800	$ 2,762
Ceded to Other Companies	90	51	50
Assumed from Other Companies	0	0	0
Premiums	$ 2,837	$ 2,749	$ 2,712
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%