Investments (Maturities of Fixed Maturity Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 13,348
Amortized Cost, Due after one year through five years	77,283
Amortized Cost, Due after five years through ten years	69,960
Amortized Cost, Due after ten years	111,474
Amortized Cost, RMBS, CMBS and ABS	71,347
Amortized Cost, Subtotal	343,412	$ 332,964
Estimated Fair Value, Due in one year or less	13,428
Estimated Fair Value, Due after one year through five years	81,212
Estimated Fair Value, Due after five years through ten years	74,104
Estimated Fair Value, Due after ten years	130,629
Estimated fair value, Mortgage-backed and asset-backed securities	72,608
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $343,412 and $332,964, respectively; includes $3,396 and $4,277, respectively, relating to variable interest entities)	$ 371,981	$ 351,402