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FAIR VALUE MEASUREMENTS - Additional Information (Detail) (USD $)
Jun. 30, 2012
Dec. 31, 2011
Jun. 30, 2011
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount $ 0   $ 0
Securities held to maturity, fixed maturities, fair value 52,540,000,000 46,383,000,000  
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount 0   0
Interest Rates
     
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Magnitude of movement 0.50%    
Credit Spreads
     
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Magnitude of movement 0.50%    
Interest Rate Volatility
     
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Magnitude of movement 50.00%    
Discounted Cash Flow Valuation Technique
     
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Fair values of available-for-sale fixed maturity and perpetual securities valued by our DCF pricing model 18,600,000,000    
Securities held to maturity, fixed maturities, fair value $ 23,500,000,000    
Available-for-sale Securities | Level 2
     
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Percentage of fair value of investments valued by obtaining quoted market prices from investment custodian 52.00%    
Percentage of holdings valued by obtaining quoted market prices from investment custodian 76.00%    
Percentage of fair value of investments using DCF pricing model 42.00%    
Percentage of holdings of investments using discounted cash flow pricing model 10.00%    
Percentage of fair value of investments using other pricing services 6.00%    
Percentage of holdings of investments using other pricing services 14.00%    
Held-to-maturity Securities | Level 2
     
Fair Value, Measurement Inputs, Disclosure [Line Items]      
Percentage of fair value of investments valued by obtaining quoted market prices from investment custodian 3.00%    
Percentage of holdings valued by obtaining quoted market prices from investment custodian 7.00%    
Percentage of fair value of investments using DCF pricing model 94.00%    
Percentage of holdings of investments using discounted cash flow pricing model 84.00%    
Percentage of fair value of investments using other pricing services 3.00%    
Percentage of holdings of investments using other pricing services 9.00%