Investments (Details 11) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other details of unrealized loss
Unrealized losses related to securities with unrealized loss position less than 20% of cost or amortized cost	$ 504
Unrealized losses related to securities with unrealized loss position greater than or equal to 20% of cost or amortized cost	103
Limited partnership impairment
Limited partnership interests	4,967	4,922
Write-downs of limited partnership	207	239	563
Investment grade fixed income securities
Other details of unrealized loss
Unrealized losses related to securities with unrealized loss position less than 20% of cost or amortized cost	383
Unrealized losses related to securities with unrealized loss position greater than or equal to 20% of cost or amortized cost	73
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 cost or amortized cost	25
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	17
Equity securities
Other details of unrealized loss
Unrealized losses related to securities with unrealized loss position greater than or equal to 20% of cost or amortized cost	5
Limited partnership impairment
Write-downs of limited partnership	137	75	139
Equity-method limited partnerships
Limited partnership impairment
Limited partnership interests	3,520	3,520
Write-downs of limited partnership	1	0	2
Cost-method limited partnership interests
Limited partnership impairment
Limited partnership interests	1,440	1,410
Write-downs of limited partnership	$ 17	$ 8	$ 4