Investments (Credit Quality of Commercial Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	$ 40,540	$ 40,926
% of Total	100.00%	100.00%
Estimated Fair Value	42,370	42,456
% of Total	100.00%	100.00%
Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	34,085	32,007
% of Total	84.10%	78.20%
Estimated Fair Value	35,851	33,519
% of Total	84.60%	78.90%
65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	5,165	6,947
% of Total	12.70%	17.00%
Estimated Fair Value	5,249	7,039
% of Total	12.40%	16.60%
76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	388	906
% of Total	1.00%	2.20%
Estimated Fair Value	396	892
% of Total	0.90%	2.10%
Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	902	1,066
% of Total	2.20%	2.60%
Estimated Fair Value	874	1,006
% of Total	2.10%	2.40%
Greater than 1.20x [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	37,349	38,098
Greater than 1.20x [Member] | Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	32,361	30,552
Greater than 1.20x [Member] | 65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	4,438	6,360
Greater than 1.20x [Member] | 76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	139	525
Greater than 1.20x [Member] | Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	411	661
1.00x - 1.20x [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	1,963	1,486
1.00x - 1.20x [Member] | Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	825	614
1.00x - 1.20x [Member] | 65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	670	438
1.00x - 1.20x [Member] | 76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	192	192
1.00x - 1.20x [Member] | Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	276	242
Less than 1.00x [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	1,228	1,342
Less than 1.00x [Member] | Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	899	841
Less than 1.00x [Member] | 65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	57	149
Less than 1.00x [Member] | 76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	57	189
Less than 1.00x [Member] | Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	$ 215	$ 163