SCHEDULE IV REINSURANCE Schedule IV - Reinsurance (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross Amount, Life Insurance in Force	$ 146,585				$ 151,457				$ 146,585	$ 151,457	$ 152,502
Ceded to Other Companies, Life Insurance in Force	6,592				4,702				6,592	4,702	4,121
Assumed from Other Companies, Life Insurance in Force	0				0				0	0	0
Net Amount, Life Insurance in Force	$ 139,993				$ 146,755				$ 139,993	$ 146,755	$ 148,381
Percentage of Amount Assumed to Net, Life Insurance in Force	0.00%				0.00%				0.00%	0.00%	0.00%
Gross amount									$ 19,122	$ 19,018	$ 18,875
Ceded to Other Companies									547	555	566
Assumed from Other companies									205	214	222
Net Amount	$ 4,671	$ 4,736	$ 4,681	$ 4,691	$ 4,591	$ 4,636	$ 4,706	$ 4,745	$ 18,780	$ 18,677	$ 18,531
Percentage of Amount Assumed to Net									1.00%	1.00%	1.00%
Health insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross amount									$ 15,657	$ 15,330	$ 14,829
Ceded to Other Companies									527	541	554
Assumed from Other companies									205	214	222
Net Amount									$ 15,335	$ 15,003	$ 14,497
Percentage of Amount Assumed to Net									1.00%	1.00%	1.00%
Life insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross amount									$ 3,465	$ 3,688	$ 4,046
Ceded to Other Companies									20	14	12
Assumed from Other companies									0	0	0
Net Amount									$ 3,445	$ 3,674	$ 4,034
Percentage of Amount Assumed to Net									0.00%	0.00%	0.00%