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, 2012	Dec. 31, 2011
Level 3
Assets:
Total assets	$ 3,926
Liabilities:
Total liabilities	419
Fair Value, Measurements, Recurring
Assets:
Swaps	318	375
Cash and cash equivalents	2,210	2,249
Total assets	54,427	56,660
Liabilities:
Total liabilities	428	531
Fair Value, Measurements, Recurring \| Interest rate swaps
Assets:
Swaps	31	34
Liabilities:
Swaps	3	4
Fair Value, Measurements, Recurring \| Foreign currency swaps
Assets:
Swaps	287	341
Liabilities:
Swaps	328	397
Fair Value, Measurements, Recurring \| Credit default swaps
Liabilities:
Swaps	97	130
Fair Value, Measurements, Recurring \| Fixed Maturities
Assets:
Available-for-sale Securities	46,522	47,572
Fair Value, Measurements, Recurring \| Fixed Maturities \| Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	10,729	11,813
Fair Value, Measurements, Recurring \| Fixed Maturities \| Municipalities
Assets:
Available-for-sale Securities	1,163	1,159
Fair Value, Measurements, Recurring \| Fixed Maturities \| Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	1,264	1,338
Fair Value, Measurements, Recurring \| Fixed Maturities \| Public Utilities
Assets:
Available-for-sale Securities	7,335	7,225
Fair Value, Measurements, Recurring \| Fixed Maturities \| Sovereign and Supranational
Assets:
Available-for-sale Securities	2,205	2,308
Fair Value, Measurements, Recurring \| Fixed Maturities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	7,709	7,453
Fair Value, Measurements, Recurring \| Fixed Maturities \| Other Corporate
Assets:
Available-for-sale Securities	16,117	16,276
Fair Value, Measurements, Recurring \| Perpetual Securities
Assets:
Available-for-sale Securities	5,352	6,439
Fair Value, Measurements, Recurring \| Perpetual Securities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	5,001	6,078
Fair Value, Measurements, Recurring \| Perpetual Securities \| Other Corporate
Assets:
Available-for-sale Securities	351	361
Fair Value, Measurements, Recurring \| Equity Securities
Assets:
Available-for-sale Securities	25	25
Fair Value, Measurements, Recurring \| Level 1
Assets:
Swaps	0	0
Cash and cash equivalents	2,210	2,249
Total assets	12,190	13,356
Liabilities:
Total liabilities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Interest rate swaps
Assets:
Swaps	0	0
Liabilities:
Swaps	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Foreign currency swaps
Assets:
Swaps	0	0
Liabilities:
Swaps	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Credit default swaps
Liabilities:
Swaps	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities
Assets:
Available-for-sale Securities	9,965	11,092
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	9,965	11,092
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Municipalities
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Public Utilities
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Sovereign and Supranational
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Fixed Maturities \| Other Corporate
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Perpetual Securities
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Perpetual Securities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Perpetual Securities \| Other Corporate
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Equity Securities
Assets:
Available-for-sale Securities	15	15
Fair Value, Measurements, Recurring \| Level 2
Assets:
Swaps	47	0
Cash and cash equivalents	0	0
Total assets	38,311	38,970
Liabilities:
Total liabilities	9	0
Fair Value, Measurements, Recurring \| Level 2 \| Interest rate swaps
Assets:
Swaps	0	0
Liabilities:
Swaps	0	0
Fair Value, Measurements, Recurring \| Level 2 \| Foreign currency swaps
Assets:
Swaps	47	0
Liabilities:
Swaps	9	0
Fair Value, Measurements, Recurring \| Level 2 \| Credit default swaps
Liabilities:
Swaps	0	0
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities
Assets:
Available-for-sale Securities	33,231	33,051
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	764	721
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Municipalities
Assets:
Available-for-sale Securities	1,163	1,159
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	897	944
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Public Utilities
Assets:
Available-for-sale Securities	6,926	6,803
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Sovereign and Supranational
Assets:
Available-for-sale Securities	1,787	1,874
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	6,612	6,379
Fair Value, Measurements, Recurring \| Level 2 \| Fixed Maturities \| Other Corporate
Assets:
Available-for-sale Securities	15,082	15,171
Fair Value, Measurements, Recurring \| Level 2 \| Perpetual Securities
Assets:
Available-for-sale Securities	5,027	5,913
Fair Value, Measurements, Recurring \| Level 2 \| Perpetual Securities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	4,676	5,552
Fair Value, Measurements, Recurring \| Level 2 \| Perpetual Securities \| Other Corporate
Assets:
Available-for-sale Securities	351	361
Fair Value, Measurements, Recurring \| Level 2 \| Equity Securities
Assets:
Available-for-sale Securities	6	6
Fair Value, Measurements, Recurring \| Level 3
Assets:
Swaps	271	375
Cash and cash equivalents	0	0
Total assets	3,926	4,334
Liabilities:
Total liabilities	419	531
Fair Value, Measurements, Recurring \| Level 3 \| Interest rate swaps
Assets:
Swaps	31	34
Liabilities:
Swaps	3	4
Fair Value, Measurements, Recurring \| Level 3 \| Foreign currency swaps
Assets:
Swaps	240	341
Liabilities:
Swaps	319	397
Fair Value, Measurements, Recurring \| Level 3 \| Credit default swaps
Liabilities:
Swaps	97	130
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities
Assets:
Available-for-sale Securities	3,326	3,429
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Government and Agencies Debt Securities
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Municipalities
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	367	394
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Public Utilities
Assets:
Available-for-sale Securities	409	422
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Sovereign and Supranational
Assets:
Available-for-sale Securities	418	434
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	1,097	1,074
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Maturities \| Other Corporate
Assets:
Available-for-sale Securities	1,035	1,105
Fair Value, Measurements, Recurring \| Level 3 \| Perpetual Securities
Assets:
Available-for-sale Securities	325	526
Fair Value, Measurements, Recurring \| Level 3 \| Perpetual Securities \| Banks/financial Institutions
Assets:
Available-for-sale Securities	325	526
Fair Value, Measurements, Recurring \| Level 3 \| Perpetual Securities \| Other Corporate
Assets:
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Equity Securities
Assets:
Available-for-sale Securities	4	4
Carrying Value
Assets:
Swaps	318	375
Liabilities:
Swaps	$ 428	$ 531

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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- Definition

Derivative instrument obligations meeting the definition of a liability which the Company is a party to as of the balance sheet date.

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