INVESTMENTS - Contractual and Economic Maturities of Investments in Fixed Maturities (Detail) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Available for sale:
Due in one year or less	[1]	$ 485
Due after one year through five years	[1]	9,685
Due after five years through 10 years	[1]	10,637
Due after 10 years	[1]	60,381
Mortgage- and asset-backed securities	[1]	419
Total fixed maturity securities, available for sale, amortized cost	[1]	81,607
Held to maturity:
Due in one year or less		1,036
Due after one year through five years		508
Due after five years through 10 years		1,597
Due after 10 years		30,210
Mortgage- and asset-backed securities		26
Total fixed maturity securities, held to maturity, amortized cost		33,377	$ 31,430
Available for sale:
Due in one year or less	[1]	502
Due after one year through five years	[1]	9,551
Due after five years through 10 years	[1]	11,143
Due after 10 years	[1]	67,382
Mortgage- and asset-backed securities	[1]	455
Total fixed maturity securities, available for sale, fair value	[1]	89,033
Held to maturity:
Due in one year or less		1,049
Due after one year through five years		527
Due after five years through 10 years		1,754
Due after 10 years		37,110
Mortgage- and asset-backed securities		28
Total fixed maturity securities, held to maturity, fair value		$ 40,468	$ 38,072

[1] Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)