Investments (Unconsolidated Variable Interest Entities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Carrying Amount Asset	$ 14,917	$ 11,725
Carrying Amount liability	15,315	12,127
Other limited partnership interests
Variable Interest Entity [Line Items]
Carrying Amount Asset	1,767	1,774
Carrying Amount liability	2,156	2,162
Real estate joint ventures
Variable Interest Entity [Line Items]
Carrying Amount Asset	47	47
Carrying Amount liability	51	51
Other invested assets
Variable Interest Entity [Line Items]
Carrying Amount Asset	41	37
Carrying Amount liability	46	47
Structured securities (RMBS, CMBS and ABS)
Variable Interest Entity [Line Items]
Carrying Amount Asset	12,503	9,322
Carrying Amount liability	12,503	9,322
U.S. and foreign corporate
Variable Interest Entity [Line Items]
Carrying Amount Asset	541	526
Carrying Amount liability	541	526
Non-redeemable preferred stock
Variable Interest Entity [Line Items]
Carrying Amount Asset	18	19
Carrying Amount liability	$ 18	$ 19