Schedule IV - Reinsurance (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Life insurance in force
Gross amount	$ 208,417,000,000	$ 219,785,000,000	$ 207,434,000,000
Ceded to other companies	67,319,000,000	74,021,000,000	81,186,000,000
Assumed from other companies	217,020,000,000	229,419,000,000	243,161,000,000
Net amount	$ 358,118,000,000	$ 375,183,000,000	$ 369,409,000,000
Percentage of amount assumed to net	60.60%	61.10%	65.80%
Premiums and contract charges:
Property and casualty insurance	$ 40,116,000,000	$ 39,178,000,000	$ 36,978,000,000
Ceded to other companies	1,383,000,000	1,407,000,000	1,306,000,000
Assumed from other companies	784,000,000	806,000,000	841,000,000
Net amount	$ 39,517,000,000	$ 38,577,000,000	$ 36,513,000,000
Percentage of amount assumed to net	2.00%	2.10%	2.30%
Reinsurance or coinsurance income netted against premium ceded	$ 0	$ 0	$ 0
Life insurance
Premiums and contract charges:
Property and casualty insurance	1,053,000,000	1,062,000,000	994,000,000
Ceded to other companies	222,000,000	262,000,000	266,000,000
Assumed from other companies	685,000,000	712,000,000	754,000,000
Net amount	$ 1,516,000,000	$ 1,512,000,000	$ 1,482,000,000
Percentage of amount assumed to net	45.20%	47.10%	50.90%
Accident and health insurance
Premiums and contract charges:
Property and casualty insurance	$ 948,000,000	$ 1,012,000,000	$ 1,007,000,000
Ceded to other companies	20,000,000	23,000,000	24,000,000
Assumed from other companies	0	0	0
Net amount	$ 928,000,000	$ 989,000,000	$ 983,000,000
Percentage of amount assumed to net	0.00%	0.00%	0.00%
Property and casualty insurance
Premiums and contract charges:
Property and casualty insurance	$ 38,115,000,000	$ 37,104,000,000	$ 34,977,000,000
Ceded to other companies	1,141,000,000	1,122,000,000	1,016,000,000
Assumed from other companies	99,000,000	94,000,000	87,000,000
Net amount	$ 37,073,000,000	$ 36,076,000,000	$ 34,048,000,000
Percentage of amount assumed to net	0.30%	0.30%	0.30%