FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Assets:
Available for sale, fixed maturity securities	[1]	$ 85,881	[2],[3]	$ 84,313	[4]
Equity securities	[1],[5]	1,103
Asset derivatives		457		331
Other Investments		1		57
Cash and cash equivalents		3,847		3,491
Total assets		91,289		89,215
Liabilities:
Liability derivatives		367		474
Total liabilities		367		474
Foreign currency swaps
Assets:
Asset derivatives		321		296
Liabilities:
Liability derivatives		227		197
Foreign currency forwards
Assets:
Asset derivatives		136		22
Liabilities:
Liability derivatives		135		274
Foreign currency options
Assets:
Asset derivatives				12
Liabilities:
Liability derivatives		5		3
Credit default swaps
Assets:
Asset derivatives				1
Fixed maturities
Assets:
Available for sale, fixed maturity securities	[1]	85,881		84,313
Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		35,116		31,230
Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		1,928		1,370
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		347		444
Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		7,364		7,954
Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		1,743		1,909
Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		9,182		8,933
Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		30,201		32,473
Equity securities
Assets:
Equity securities, available-for-sale				1,023
Level 1
Assets:
Available for sale, fixed maturity securities		33,591		30,109
Equity securities		1,011
Asset derivatives		0		0
Other Investments		1		57
Cash and cash equivalents		3,847		3,491
Total assets		38,450		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 | Credit default swaps
Assets:
Asset derivatives				0
Level 1 | Fixed maturities
Assets:
Available for sale, fixed maturity securities		33,591		30,109
Level 1 | Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		33,591		30,109
Level 1 | Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Equity securities
Assets:
Equity securities, available-for-sale				1,001
Level 2
Assets:
Available for sale, fixed maturity securities		51,787		53,790
Equity securities		75
Asset derivatives		255		180
Other Investments		0		0
Cash and cash equivalents		0		0
Total assets		52,117		53,976
Liabilities:
Total liabilities		275		346
Level 2 | Foreign currency swaps
Assets:
Asset derivatives		119		146
Liabilities:
Liability derivatives		135		69
Level 2 | Foreign currency forwards
Assets:
Asset derivatives		136		22
Liabilities:
Liability derivatives		135		274
Level 2 | Foreign currency options
Assets:
Asset derivatives				12
Liabilities:
Liability derivatives		5		3
Level 2 | Credit default swaps
Assets:
Asset derivatives				0
Level 2 | Fixed maturities
Assets:
Available for sale, fixed maturity securities		51,787		53,790
Level 2 | Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		1,525		1,121
Level 2 | Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		1,928		1,370
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		169		269
Level 2 | Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		7,258		7,886
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		1,743		1,909
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		9,159		8,908
Level 2 | Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		30,005		32,327
Level 2 | Equity securities
Assets:
Equity securities, available-for-sale				6
Level 3
Assets:
Available for sale, fixed maturity securities		503		414
Equity securities		17
Asset derivatives		202		151
Other Investments		0		0
Cash and cash equivalents		0		0
Total assets		722		581
Liabilities:
Total liabilities		92		128
Level 3 | Foreign currency swaps
Assets:
Asset derivatives		202		150
Liabilities:
Liability derivatives		92		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 | Credit default swaps
Assets:
Asset derivatives				1
Level 3 | Fixed maturities
Assets:
Available for sale, fixed maturity securities		503		414
Level 3 | Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		0		0
Level 3 | Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		0		0
Level 3 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		178		175
Level 3 | Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		106		68
Level 3 | Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		0		0
Level 3 | Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		23		25
Level 3 | Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		$ 196		146
Level 3 | Equity securities
Assets:
Equity securities, available-for-sale				$ 16

[1] Includes perpetual securities

[2] Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)

[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 ($69 at fair value)