v3.8.0.1
Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Available for Sale, Amortized Cost    
Due in one year or less $ 8,244  
Due after one year through five years 47,967  
Due after five years through ten years 69,445  
Due after ten years 158,139  
Amortized Cost 312,385 $ 292,581
Available-for-Sale, Fair Value    
Due in one year or less 8,711  
Due after one year through five years 51,936  
Due after five years through ten years 75,596  
Due after ten years 181,378  
Fair Value [1] 346,780 321,419
Held-to-Maturity, Amortized Cost    
Due in one year or less 0  
Due after one year through five years 176  
Due after five years through ten years 565  
Due after ten years 862  
Amortized Cost [1] 2,049 2,144
Held-to-Maturity, Fair Value    
Due in one year or less 0  
Due after one year through five years 183  
Due after five years through ten years 642  
Due after ten years 1,127  
Fixed maturities, held to maturity, fair value 2,430 2,524
Asset-backed securities    
Available for Sale, Amortized Cost    
Debt Maturities, without single maturity date 11,965  
Available-for-Sale, Fair Value    
Debt Maturities, without Single Maturity Date 12,233  
Held-to-Maturity, Amortized Cost    
Debt Maturities, without Single Maturity Date 0  
Held-to-Maturity, Fair Value    
Debt Maturities, without Single Maturity Date 0  
Commercial Mortgage Backed Securities    
Available for Sale, Amortized Cost    
Debt Maturities, without single maturity date 13,134  
Available-for-Sale, Fair Value    
Debt Maturities, without Single Maturity Date 13,281  
Held-to-Maturity, Amortized Cost    
Debt Maturities, without Single Maturity Date 0  
Held-to-Maturity, Fair Value    
Debt Maturities, without Single Maturity Date 0  
Residential mortgage-backed securities    
Available for Sale, Amortized Cost    
Debt Maturities, without single maturity date 3,491  
Available-for-Sale, Fair Value    
Debt Maturities, without Single Maturity Date 3,645  
Held-to-Maturity, Amortized Cost    
Debt Maturities, without Single Maturity Date 446  
Held-to-Maturity, Fair Value    
Debt Maturities, without Single Maturity Date 478  
Prudential Netting Agreement | U.S. corporate private securities    
Available-for-Sale, Fair Value    
Fair Value 2,660 1,456
Fixed maturities    
Available for Sale, Amortized Cost    
Amortized Cost 312,385 292,581
Available-for-Sale, Fair Value    
Fair Value 346,780 321,419
Held-to-Maturity, Amortized Cost    
Amortized Cost 2,049 2,144
Held-to-Maturity, Fair Value    
Fixed maturities, held to maturity, fair value 2,430 2,524
Fixed maturities | U.S. corporate private securities    
Available for Sale, Amortized Cost    
Amortized Cost 31,852 29,974
Available-for-Sale, Fair Value    
Fair Value 33,734 31,788
Fixed maturities | Asset-backed securities    
Available for Sale, Amortized Cost    
Amortized Cost 11,965 11,759
Available-for-Sale, Fair Value    
Fair Value 12,233 11,935
Fixed maturities | Commercial Mortgage Backed Securities    
Available for Sale, Amortized Cost    
Amortized Cost 13,134 12,589
Available-for-Sale, Fair Value    
Fair Value 13,281 12,704
Held-to-Maturity, Amortized Cost    
Amortized Cost 0 0
Held-to-Maturity, Fair Value    
Fixed maturities, held to maturity, fair value 0 0
Fixed maturities | Residential mortgage-backed securities    
Available for Sale, Amortized Cost    
Amortized Cost 3,491 4,308
Available-for-Sale, Fair Value    
Fair Value 3,645 4,532
Held-to-Maturity, Amortized Cost    
Amortized Cost 446 573
Held-to-Maturity, Fair Value    
Fixed maturities, held to maturity, fair value 478 616
Fixed maturities | Prudential Netting Agreement    
Held-to-Maturity, Amortized Cost    
Amortized Cost 4,627 4,403
Held-to-Maturity, Fair Value    
Fixed maturities, held to maturity, fair value 4,913 4,403
Fixed maturities | Prudential Netting Agreement | U.S. corporate private securities    
Available for Sale, Amortized Cost    
Amortized Cost 2,660 1,456
Available-for-Sale, Fair Value    
Fair Value $ 2,660 $ 1,456
[1] See Note 5 for details of balances associated with variable interest entities.