FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets:
Available for sale, fixed maturity securities	$ 91,262	$ 82,895
Equity securities	802	987
Other investments	628	152
Cash and cash equivalents	4,896	4,337
Asset derivatives	482	417
Total assets	98,070	88,788
Liabilities:
Liability derivatives	586	387
Total liabilities	586	387
Foreign currency swaps
Assets:
Asset derivatives	241	285
Liabilities:
Liability derivatives	204	234
Foreign currency forwards
Assets:
Asset derivatives	238	126
Liabilities:
Liability derivatives	377	151
Foreign currency options
Assets:
Asset derivatives		3
Liabilities:
Liability derivatives	5	1
Interest rate swaptions
Liabilities:
Liability derivatives		1
Interest rate swaps
Assets:
Asset derivatives	3	3
Government and agencies
Assets:
Available for sale, fixed maturity securities	36,400	34,342
Municipalities
Assets:
Available for sale, fixed maturity securities	1,847	1,863
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	410	339
Public utilities
Assets:
Available for sale, fixed maturity securities	6,780	7,171
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,042	1,260
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	10,287	8,918
Other corporate
Assets:
Available for sale, fixed maturity securities	34,496	29,002
Level 1
Assets:
Available for sale, fixed maturity securities	34,878	32,993
Equity securities	642	874
Other investments	628	152
Cash and cash equivalents	4,896	4,337
Asset derivatives	0	0
Total assets	41,044	38,356
Liabilities:
Total liabilities	0	0
Level 1 \| Foreign currency swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 \| Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 \| Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 1 \| Interest rate swaptions
Liabilities:
Liability derivatives		0
Level 1 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Level 1 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	34,878	32,993
Level 1 \| Municipalities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Public utilities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Other corporate
Assets:
Available for sale, fixed maturity securities	0	0
Level 2
Assets:
Available for sale, fixed maturity securities	55,697	49,380
Equity securities	80	67
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	313	235
Total assets	56,090	49,682
Liabilities:
Total liabilities	460	285
Level 2 \| Foreign currency swaps
Assets:
Asset derivatives	72	103
Liabilities:
Liability derivatives	78	132
Level 2 \| Foreign currency forwards
Assets:
Asset derivatives	238	126
Liabilities:
Liability derivatives	377	151
Level 2 \| Foreign currency options
Assets:
Asset derivatives		3
Liabilities:
Liability derivatives	5	1
Level 2 \| Interest rate swaptions
Liabilities:
Liability derivatives		1
Level 2 \| Interest rate swaps
Assets:
Asset derivatives	3	3
Level 2 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	1,522	1,349
Level 2 \| Municipalities
Assets:
Available for sale, fixed maturity securities	1,847	1,863
Level 2 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	232	162
Level 2 \| Public utilities
Assets:
Available for sale, fixed maturity securities	6,556	7,062
Level 2 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,042	1,260
Level 2 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	10,264	8,895
Level 2 \| Other corporate
Assets:
Available for sale, fixed maturity securities	34,234	28,789
Level 3
Assets:
Available for sale, fixed maturity securities	687	522
Equity securities	80	46
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	169	182
Total assets	936	750
Liabilities:
Total liabilities	126	102
Level 3 \| Foreign currency swaps
Assets:
Asset derivatives	169	182
Liabilities:
Liability derivatives	126	102
Level 3 \| Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 \| Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 3 \| Interest rate swaptions
Liabilities:
Liability derivatives		0
Level 3 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Level 3 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Municipalities
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	178	177
Level 3 \| Public utilities
Assets:
Available for sale, fixed maturity securities	224	109
Level 3 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	23	23
Level 3 \| Other corporate
Assets:
Available for sale, fixed maturity securities	$ 262	$ 213

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