FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Sep. 30, 2018		Dec. 31, 2017
Assets:
Available for sale, fixed maturity securities	[2]	$ 82,296	[1],[3]	$ 84,313	[4]
Equity securities, available-for-sale				1,023
Equity securities	[2],[5]	1,059
Asset derivatives		430		331
Other investments		2		57
Cash and cash equivalents		3,429		3,491
Total assets		87,216		89,215
Liabilities:
Liability derivatives		497		474
Total liabilities		497		474
Foreign currency swaps
Assets:
Asset derivatives		302		296
Liabilities:
Liability derivatives		207		197
Foreign currency forwards
Assets:
Asset derivatives		128		22
Liabilities:
Liability derivatives		277		274
Foreign currency options
Assets:
Asset derivatives				12
Liabilities:
Liability derivatives		12		3
Interest rate swaps
Liabilities:
Liability derivatives		1
Credit default swaps
Assets:
Asset derivatives				1
Government and agencies
Assets:
Available for sale, fixed maturity securities		32,170		31,230
Municipalities
Assets:
Available for sale, fixed maturity securities		1,834		1,370
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		333		444
Public utilities
Assets:
Available for sale, fixed maturity securities		7,313		7,954
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		1,557		1,909
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		8,939		8,933
Other corporate
Assets:
Available for sale, fixed maturity securities		30,150		32,473
Level 1
Assets:
Available for sale, fixed maturity securities		30,888		30,109
Equity securities, available-for-sale				1,001
Equity securities		972
Asset derivatives		0		0
Other investments		2		57
Cash and cash equivalents		3,429		3,491
Total assets		35,291		34,658
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 swaps
Liabilities:
Liability derivatives		0
Level 1 | Credit default swaps
Assets:
Asset derivatives				0
Level 1 | Government and agencies
Assets:
Available for sale, fixed maturity securities		30,888		30,109
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		50,918		53,790
Equity securities, available-for-sale				6
Equity securities		71
Asset derivatives		240		180
Other investments		0		0
Cash and cash equivalents		0		0
Total assets		51,229		53,976
Liabilities:
Total liabilities		396		346
Level 2 | Foreign currency swaps
Assets:
Asset derivatives		112		146
Liabilities:
Liability derivatives		106		69
Level 2 | Foreign currency forwards
Assets:
Asset derivatives		128		22
Liabilities:
Liability derivatives		277		274
Level 2 | Foreign currency options
Assets:
Asset derivatives				12
Liabilities:
Liability derivatives		12		3
Level 2 | Interest rate swaps
Liabilities:
Liability derivatives		1
Level 2 | Credit default swaps
Assets:
Asset derivatives				0
Level 2 | Government and agencies
Assets:
Available for sale, fixed maturity securities		1,282		1,121
Level 2 | Municipalities
Assets:
Available for sale, fixed maturity securities		1,834		1,370
Level 2 | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		161		269
Level 2 | Public utilities
Assets:
Available for sale, fixed maturity securities		7,209		7,886
Level 2 | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		1,557		1,909
Level 2 | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		8,916		8,908
Level 2 | Other corporate
Assets:
Available for sale, fixed maturity securities		29,959		32,327
Level 3
Assets:
Available for sale, fixed maturity securities		490		414
Equity securities, available-for-sale				16
Equity securities		16
Asset derivatives		190		151
Other investments		0		0
Cash and cash equivalents		0		0
Total assets		696		581
Liabilities:
Total liabilities		101		128
Level 3 | Foreign currency swaps
Assets:
Asset derivatives		190		150
Liabilities:
Liability derivatives		101		128
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 swaps
Liabilities:
Liability derivatives		0
Level 3 | Credit default swaps
Assets:
Asset derivatives				1
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		172		175
Level 3 | Public utilities
Assets:
Available for sale, fixed maturity securities		104		68
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		25
Level 3 | Other corporate
Assets:
Available for sale, fixed maturity securities		$ 191		$ 146

[1] Includes perpetual securities ($1,408 at amortized cost and $1,591 at fair value)

[2] Includes perpetual securities

[3] 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)

[4] Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)

[5] Includes perpetual securities ($66 at fair value)