FAIR VALUE MEASUREMENTS - Significant Unobservable Inputs Used in the Valuation of Available-for-sale Investments and Derivatives (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Liabilities:
Length of Volatility of Japanese Yen to US Dollar Exchange Rate	10 years
Level 3
Assets:
Total assets	3,970
Liabilities:
Total liabilities	474
Level 3 | Consensus Pricing Valuation Technique | Mortgage- and asset-backed Securities
Assets:
Available-for-sale Securities	379
Level 3 | Consensus Pricing Valuation Technique | Banks/financial Institutions
Assets:
Available-for-sale Securities	534
Level 3 | Consensus Pricing Valuation Technique | Other Corporate
Assets:
Available-for-sale Securities	429
Level 3 | Discounted Cash Flow Valuation Technique | Public Utilities
Assets:
Available-for-sale Securities	418
Level 3 | Discounted Cash Flow Valuation Technique | Sovereign and Supranational
Assets:
Available-for-sale Securities	436
Level 3 | Discounted Cash Flow Valuation Technique | Banks/financial Institutions
Assets:
Available-for-sale Securities	580
Level 3 | Discounted Cash Flow Valuation Technique | Banks/financial Institutions | Perpetual Securities
Assets:
Available-for-sale Securities	307
Level 3 | Discounted Cash Flow Valuation Technique | Other Corporate
Assets:
Available-for-sale Securities	602
Level 3 | Discounted Cash Flow Valuation Technique | Interest rate swaps
Assets:
Asset Derivatives	31
Liabilities:
Swaps	4
Level 3 | Discounted Cash Flow Valuation Technique | Credit default swaps
Liabilities:
Swaps	107
Level 3 | Net Asset Value Valuation Technique | Equity Securities
Assets:
Available-for-sale Securities	4
Level 3 | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Discounted Cash Flow Valuation Technique | Foreign currency swaps
Assets:
Asset Derivatives	87
Liabilities:
Swaps	92
Level 3 | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Discounted Cash Flow Valuation Technique | Foreign currency swaps
Assets:
Asset Derivatives	35
Liabilities:
Swaps	32
Level 3 | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Discounted Cash Flow Valuation Technique | Foreign currency swaps
Assets:
Asset Derivatives	128
Liabilities:
Swaps	239
Level 3 | Liability [Member] | Lower Limit | Interest rate swaps
Unobservable Inputs
Base correlation	44.00%	[1]
CDS spreads	0.84%
Recovery rate	25.00%
Level 3 | Liability [Member] | Lower Limit | Credit default swaps
Unobservable Inputs
Base correlation	44.00%	[1]
CDS spreads	0.84%
Recovery rate	25.00%
Level 3 | Liability [Member] | Upper Limit | Interest rate swaps
Unobservable Inputs
Base correlation	54.00%	[1]
CDS spreads	1.92%
Recovery rate	70.00%
Level 3 | Liability [Member] | Upper Limit | Credit default swaps
Unobservable Inputs
Base correlation	54.00%	[1]
CDS spreads	1.92%
Recovery rate	70.00%
Level 3 | Liability [Member] | Weighted Average | Interest rate swaps
Unobservable Inputs
CDS spreads
Recovery rate	40.00%
Level 3 | Liability [Member] | Weighted Average | Credit default swaps
Unobservable Inputs
CDS spreads
Recovery rate	40.00%
Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	0.41%
Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	1.64%
Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	0.66%
Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	2.94%
Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Weighted Average | Foreign currency swaps
Unobservable Inputs
CDS spreads
Level 3 | Assets [Member] | Public Utilities
Unobservable Inputs
Historical Volatility Rate	7.43%
Level 3 | Assets [Member] | Sovereign and Supranational
Unobservable Inputs
Historical Volatility Rate	7.43%
Level 3 | Assets [Member] | Banks/financial Institutions
Unobservable Inputs
Historical Volatility Rate	7.43%
Level 3 | Assets [Member] | Banks/financial Institutions | Perpetual Securities
Unobservable Inputs
Historical Volatility Rate	7.43%
Level 3 | Assets [Member] | Other Corporate
Unobservable Inputs
Historical Volatility Rate	7.43%
Level 3 | Assets [Member] | Lower Limit | Equity Securities
Unobservable Inputs
Offered quotes (in dollars per share)	0
Level 3 | Assets [Member] | Lower Limit | Interest rate swaps
Unobservable Inputs
Base correlation	44.00%	[1]
CDS spreads	0.84%
Recovery rate	25.00%
Level 3 | Assets [Member] | Upper Limit | Equity Securities
Unobservable Inputs
Offered quotes (in dollars per share)	993
Level 3 | Assets [Member] | Upper Limit | Interest rate swaps
Unobservable Inputs
Base correlation	54.00%	[1]
CDS spreads	1.92%
Recovery rate	70.00%
Level 3 | Assets [Member] | Weighted Average | Equity Securities
Unobservable Inputs
Offered quotes (in dollars per share)	4
Level 3 | Assets [Member] | Weighted Average | Interest rate swaps
Unobservable Inputs
Recovery rate	40.00%
Level 3 | Assets [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Foreign currency swaps
Unobservable Inputs
Foreign exchange rates	20.38%	[2]
Level 3 | Assets [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	0.21%
Level 3 | Assets [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	1.38%
Level 3 | Assets [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	0.30%
Level 3 | Assets [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
CDS spreads	1.37%
Level 3 | Assets [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.78%	[3]
Level 3 | Assets [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	2.52%	[3]
Level 3 | Assets [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.78%	[3]
Level 3 | Assets [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	2.52%	[3]
Level 3 | Assets [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	0.84%	[4]
Level 3 | Assets [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.80%	[4]
Level 3 | Assets [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	0.84%	[4]
Level 3 | Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Foreign currency swaps
Unobservable Inputs
Foreign exchange rates	20.38%	[2]
Level 3 | Level 3 | Liability [Member] | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Foreign currency swaps
Unobservable Inputs
Foreign exchange rates	20.38%	[2]
Level 3 | Level 3 | Liability [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.78%	[3]
Level 3 | Level 3 | Liability [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	2.52%	[3]
Level 3 | Level 3 | Liability [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.78%	[3]
Level 3 | Level 3 | Liability [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	2.52%	[3]
Level 3 | Level 3 | Liability [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.78%	[3]
Level 3 | Level 3 | Liability [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	2.52%	[3]
Level 3 | Level 3 | Liability [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	0.84%	[4]
Level 3 | Level 3 | Liability [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.80%	[4]
Level 3 | Level 3 | Liability [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	0.84%	[4]
Level 3 | Level 3 | Liability [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.80%	[4]
Level 3 | Level 3 | Liability [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	0.84%	[4]
Level 3 | Level 3 | Liability [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.80%	[4]
Level 3 | Level 3 | Assets [Member] | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Foreign currency swaps
Unobservable Inputs
Foreign exchange rates	20.38%	[2]
Level 3 | Level 3 | Assets [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.78%	[3]
Level 3 | Level 3 | Assets [Member] | United States of America, Dollars | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	2.52%	[3]
Level 3 | Level 3 | Assets [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Lower Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	0.84%	[4]
Level 3 | Level 3 | Assets [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.80%	[4]
Level 3 | Level 3 | Assets [Member] | Japan, Yen | Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] | Upper Limit | Foreign currency swaps
Unobservable Inputs
Interest rates	1.80%	[4]

[1] Weighted-average range of base correlations for our bespoke tranches for attachment and detachment points corresponding to market indices

[2] Based on 10 year volatility of JPY/USD exchange rate

[3] Inputs derived from U.S. long-term rates to accommodate long maturity nature of our swaps

[4] Inputs derived from Japan long-term rates to accommodate long maturity nature of our swaps