FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets:
Available-for-sale Securities	$ 59,433	$ 61,578
Asset derivatives	430	345
Cash and cash equivalents	2,596	2,041
Total assets	62,459	63,964
Liabilities:
Total liabilities	643	934
Interest rate swaps
Assets:
Asset derivatives	26	32
Liabilities:
Liability derivatives	1	3
Foreign currency swaps
Assets:
Asset derivatives	381	311
Liabilities:
Liability derivatives	314	329
Foreign currency forwards
Assets:
Asset derivatives	19
Liabilities:
Liability derivatives	272	535
Foreign currency options
Assets:
Asset derivatives	2
Credit default swaps
Assets:
Asset derivatives	2	2
Liabilities:
Liability derivatives	56	67
Fixed Maturities
Assets:
Available-for-sale Securities	56,276	57,253
Fixed Maturities | Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	12,894	12,997
Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	1,161	1,195
Fixed Maturities | Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	954	1,031
Fixed Maturities | Public Utilities
Assets:
Available-for-sale Securities	8,150	8,497
Fixed Maturities | Sovereign and Supranational
Assets:
Available-for-sale Securities	1,752	2,072
Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	6,971	7,634
Fixed Maturities | Other Corporate
Assets:
Available-for-sale Securities	24,394	23,827
Perpetual Securities
Assets:
Available-for-sale Securities	3,133	4,302
Perpetual Securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	2,915	3,950
Perpetual Securities | Other Corporate
Assets:
Available-for-sale Securities	218	352
Equity Securities
Assets:
Available-for-sale Securities	24	23
Level 1
Assets:
Available-for-sale Securities	12,205	12,278
Asset derivatives	0	0
Cash and cash equivalents	2,596	2,041
Total assets	14,801	14,319
Liabilities:
Total liabilities	0	0
Level 1 | Interest rate swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	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
Liabilities:
Liability derivatives	0	0
Level 1 | Foreign currency options
Assets:
Asset derivatives	0
Level 1 | Credit default swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 | Fixed Maturities
Assets:
Available-for-sale Securities	12,190	12,265
Level 1 | Fixed Maturities | Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	12,190	12,265
Level 1 | Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Public Utilities
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Sovereign and Supranational
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Other Corporate
Assets:
Available-for-sale Securities	0	0
Level 1 | Perpetual Securities
Assets:
Available-for-sale Securities	0	0
Level 1 | Perpetual Securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Level 1 | Perpetual Securities | Other Corporate
Assets:
Available-for-sale Securities	0	0
Level 1 | Equity Securities
Assets:
Available-for-sale Securities	15	13
Level 2
Assets:
Available-for-sale Securities	46,759	45,895
Asset derivatives	272	154
Cash and cash equivalents	0	0
Total assets	47,031	46,049
Liabilities:
Total liabilities	272	535
Level 2 | Interest rate swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	251	154
Liabilities:
Liability derivatives	0	0
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	19
Liabilities:
Liability derivatives	272	535
Level 2 | Foreign currency options
Assets:
Asset derivatives	2
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 2 | Fixed Maturities
Assets:
Available-for-sale Securities	43,621	41,802
Level 2 | Fixed Maturities | Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	704	732
Level 2 | Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	1,161	1,195
Level 2 | Fixed Maturities | Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	515	693
Level 2 | Fixed Maturities | Public Utilities
Assets:
Available-for-sale Securities	8,150	8,077
Level 2 | Fixed Maturities | Sovereign and Supranational
Assets:
Available-for-sale Securities	1,752	1,654
Level 2 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	6,945	6,610
Level 2 | Fixed Maturities | Other Corporate
Assets:
Available-for-sale Securities	24,394	22,841
Level 2 | Perpetual Securities
Assets:
Available-for-sale Securities	3,133	4,087
Level 2 | Perpetual Securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	2,915	3,735
Level 2 | Perpetual Securities | Other Corporate
Assets:
Available-for-sale Securities	218	352
Level 2 | Equity Securities
Assets:
Available-for-sale Securities	5	6
Level 3
Assets:
Available-for-sale Securities	469	3,405
Asset derivatives	158	191
Cash and cash equivalents	0	0
Total assets	627	3,596
Liabilities:
Total liabilities	371	399
Level 3 | Interest rate swaps
Assets:
Asset derivatives	26	32
Liabilities:
Liability derivatives	1	3
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	130	157
Liabilities:
Liability derivatives	314	329
Level 3 | Foreign currency forwards
Assets:
Asset derivatives	0
Liabilities:
Liability derivatives	0	0
Level 3 | Foreign currency options
Assets:
Asset derivatives	0
Level 3 | Credit default swaps
Assets:
Asset derivatives	2	2
Liabilities:
Liability derivatives	56	67
Level 3 | Fixed Maturities
Assets:
Available-for-sale Securities	465	3,186
Level 3 | Fixed Maturities | Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities | Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	439	338
Level 3 | Fixed Maturities | Public Utilities
Assets:
Available-for-sale Securities	0	420
Level 3 | Fixed Maturities | Sovereign and Supranational
Assets:
Available-for-sale Securities	0	418
Level 3 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	26	1,024
Level 3 | Fixed Maturities | Other Corporate
Assets:
Available-for-sale Securities	0	986
Level 3 | Perpetual Securities
Assets:
Available-for-sale Securities	0	215
Level 3 | Perpetual Securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0	215
Level 3 | Perpetual Securities | Other Corporate
Assets:
Available-for-sale Securities	0	0
Level 3 | Equity Securities
Assets:
Available-for-sale Securities	$ 4	$ 4