Investments (Credit Quality of Commercial Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	$ 40,604	$ 40,926
% of Total	100.00%	100.00%
Estimated Fair Value	42,807	42,456
% of Total	100.00%	100.00%
Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	32,779	32,007
% of Total	80.70%	78.20%
Estimated Fair Value	34,876	33,519
% of Total	81.50%	78.90%
65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	6,068	6,947
% of Total	15.00%	17.00%
Estimated Fair Value	6,206	7,039
% of Total	14.50%	16.60%
76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	817	906
% of Total	2.00%	2.20%
Estimated Fair Value	816	892
% of Total	1.90%	2.10%
Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	940	1,066
% of Total	2.30%	2.60%
Estimated Fair Value	909	1,006
% of Total	2.10%	2.40%
Greater than 1.20x [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	38,143	38,098
Greater than 1.20x [Member] | Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	31,658	30,552
Greater than 1.20x [Member] | 65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	5,513	6,360
Greater than 1.20x [Member] | 76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	548	525
Greater than 1.20x [Member] | Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	424	661
1.00x - 1.20x [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	1,600	1,486
1.00x - 1.20x [Member] | Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	587	614
1.00x - 1.20x [Member] | 65% to 75% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	498	438
1.00x - 1.20x [Member] | 76% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	212	192
1.00x - 1.20x [Member] | Greater than 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	303	242
Less than 1.00x [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	861	1,342
Less than 1.00x [Member] | Less than 65% [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans	534	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	$ 213	$ 163