Investments (AFS contractual maturity) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Amortized Cost
Due within one year	$ 1,028
Due after one year through five years	5,685
Due after five years through 10 years	5,011
Due after 10 years	3,511
Total having single maturity dates	15,235
Amortized Cost	22,046	22,904
Fair Value
Due within one year	1,053
Due after one year through five years	6,301
Due after five years through 10 years	5,345
Due after 10 years	4,369
Total having single maturity dates	17,068
Fair Value	24,183	24,393
Residential Mortgage Backed Securities [Member]
Amortized Cost
Without single maturity dates	3,652
Amortized Cost	3,652	3,773
Fair Value
Without single maturity dates	3,760
Fair Value	3,760	3,811
Commercial Mortgage Backed Securities [Member]
Amortized Cost
Without single maturity dates	2,222
Amortized Cost	2,222	2,309
Fair Value
Without single maturity dates	2,358
Fair Value	2,358	2,434
Asset backed securities
Amortized Cost
Without single maturity dates	935
Amortized Cost	935	938
Fair Value
Without single maturity dates	989
Fair Value	989	981
Common Stock [Member]
Amortized Cost
Without single maturity dates	2
Amortized Cost	2	2
Fair Value
Without single maturity dates	8
Fair Value	$ 8	$ 6