SCHEDULE IV REINSURANCE Schedule IV - Reinsurance (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross Amount, Life Insurance in Force	$ 148,801				$ 146,585				$ 148,801	$ 146,585	$ 151,457
Ceded to Other Companies, Life Insurance in Force	7,016				6,592				7,016	6,592	4,702
Assumed from Other Companies, Life Insurance in Force	20,662				0				20,662	0	0
Net Amount, Life Insurance in Force	$ 162,447				$ 139,993				$ 162,447	$ 139,993	$ 146,755
Percentage of Amount Assumed to Net, Life Insurance in Force	13.00%				0.00%				13.00%	0.00%	0.00%
Gross amount									$ 18,955	$ 19,122	$ 19,018
Ceded to Other Companies									553	547	555
Assumed from Other companies									220	205	214
Net Amount	$ 4,653	$ 4,623	$ 4,664	$ 4,681	$ 4,671	$ 4,736	$ 4,681	$ 4,691	$ 18,622	$ 18,780	$ 18,677
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									$ 15,682	$ 15,657	$ 15,330
Ceded to Other Companies									526	527	541
Assumed from Other companies									213	205	214
Net Amount									$ 15,369	$ 15,335	$ 15,003
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									$ 3,273	$ 3,465	$ 3,688
Ceded to Other Companies									27	20	14
Assumed from Other companies									7	0	0
Net Amount									$ 3,253	$ 3,445	$ 3,674
Percentage of Amount Assumed to Net									0.00%	0.00%	0.00%