SCHEDULE IV REINSURANCE Schedule IV - Reinsurance (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross Amount, Life Insurance in Force	$ 151,457				$ 152,502				$ 151,457	$ 152,502	$ 151,093
Ceded to Other Companies, Life Insurance in Force	4,702				4,121				4,702	4,121	3,741
Assumed from Other Companies, Life Insurance in Force	0				0				0	0	0
Net Amount, Life Insurance in Force	$ 146,755				$ 148,381				$ 146,755	$ 148,381	$ 147,352
Percentage of Amount Assumed to Net, Life Insurance in Force	0.00%				0.00%				0.00%	0.00%	0.00%
Gross amount									$ 19,018	$ 18,875	$ 19,592
Ceded to Other Companies									555	566	608
Assumed from Other companies									214	222	241
Net Amount	$ 4,591	$ 4,636	$ 4,706	$ 4,745	$ 4,580	$ 4,648	$ 4,665	$ 4,638	$ 18,677	$ 18,531	$ 19,225
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									$ 15,330	$ 14,829	$ 14,839
Ceded to Other Companies									541	554	595
Assumed from Other companies									214	222	241
Net Amount									$ 15,003	$ 14,497	$ 14,485
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									$ 3,688	$ 4,046	$ 4,753
Ceded to Other Companies									14	12	13
Assumed from Other companies									0	0	0
Net Amount									$ 3,674	$ 4,034	$ 4,740
Percentage of Amount Assumed to Net									0.00%	0.00%	0.00%