Investments (Details 12) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Other details of unrealized loss
Unrealized losses related to securities with unrealized loss position less than 20% of amortized cost or cost	$ 121
Unrealized losses related to securities with unrealized loss position greater than or equal to 20% of amortized cost or cost	38
Limited partnership interests	1,933	2,064
Tax credit funds	285
Equity method limited partnerships
Other details of unrealized loss
Limited partnership interests	1,410	1,460
Cost method limited partnership interests
Other details of unrealized loss
Limited partnership interests	526	605
Investment grade fixed income securities
Other details of unrealized loss
Unrealized losses related to securities with unrealized loss position less than 20% of amortized cost or cost	75
Unrealized losses related to securities with unrealized loss position greater than or equal to 20% of amortized cost or cost	24
Below investment grade fixed income securities
Other details of unrealized loss
Unrealized losses related to securities with unrealized loss position greater than or equal to 20% of amortized cost or cost	14
Unrealized losses related to securities with unrealized loss position greater than 20% of cost or amortized cost, unrealized loss position of 12 or more consecutive months	$ 10