FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets:
Available for sale, fixed maturity securities	$ 100,744	$ 105,882
Equity securities	1,174	1,283
Other investments	1,295	1,139
Cash and cash equivalents	4,990	5,141
Asset derivatives	841	583
Total assets	109,044	114,028
Liabilities:
Liability derivatives	1,094	697
Total liabilities	1,094	697
Foreign currency swaps
Assets:
Asset derivatives	201	180
Liabilities:
Liability derivatives	242	312
Foreign currency forwards
Assets:
Asset derivatives	596	402
Liabilities:
Liability derivatives	766	385
Foreign currency options
Assets:
Asset derivatives	44	1
Liabilities:
Liability derivatives	86
Government and agencies
Assets:
Available for sale, fixed maturity securities	35,791	37,350
Municipalities
Assets:
Available for sale, fixed maturity securities	2,901	3,018
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	1,184	1,038
Public utilities
Assets:
Available for sale, fixed maturity securities	10,199	10,817
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,275	1,382
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	11,575	12,060
Other corporate
Assets:
Available for sale, fixed maturity securities	37,819	40,217
Level 1
Assets:
Available for sale, fixed maturity securities	34,432	36,032
Equity securities	971	1,095
Other investments	1,295	1,139
Cash and cash equivalents	4,990	5,141
Asset derivatives	0	0
Total assets	41,688	43,407
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	0
Liabilities:
Liability derivatives	0
Level 1 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	34,432	36,032
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	65,214	68,833
Equity securities	81	86
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	703	450
Total assets	65,998	69,369
Liabilities:
Total liabilities	876	466
Level 2 \| Foreign currency swaps
Assets:
Asset derivatives	63	47
Liabilities:
Liability derivatives	24	81
Level 2 \| Foreign currency forwards
Assets:
Asset derivatives	596	402
Liabilities:
Liability derivatives	766	385
Level 2 \| Foreign currency options
Assets:
Asset derivatives	44	1
Liabilities:
Liability derivatives	86
Level 2 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	1,359	1,318
Level 2 \| Municipalities
Assets:
Available for sale, fixed maturity securities	2,901	3,018
Level 2 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	980	814
Level 2 \| Public utilities
Assets:
Available for sale, fixed maturity securities	9,720	10,395
Level 2 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,207	1,334
Level 2 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	11,547	12,036
Level 2 \| Other corporate
Assets:
Available for sale, fixed maturity securities	37,500	39,918
Level 3
Assets:
Available for sale, fixed maturity securities	1,098	1,017
Equity securities	122	102
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	138	133
Total assets	1,358	1,252
Liabilities:
Total liabilities	218	231
Level 3 \| Foreign currency swaps
Assets:
Asset derivatives	138	133
Liabilities:
Liability derivatives	218	231
Level 3 \| Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 \| Foreign currency options
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	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	204	224
Level 3 \| Public utilities
Assets:
Available for sale, fixed maturity securities	479	422
Level 3 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	68	48
Level 3 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	28	24
Level 3 \| Other corporate
Assets:
Available for sale, fixed maturity securities	$ 319	$ 299

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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