Investments (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Investment Income [Line Items]
Gross investment income	$ 1,363	$ 1,318	$ 1,242
Investment expenses	(17)	(17)	(17)
Net investment income	1,346	1,301	1,225
Fixed maturities [Member]
Net Investment Income [Line Items]
Gross investment income	1,241	1,216	1,142
Equity securities [Member]
Net Investment Income [Line Items]
Gross investment income	50	36	29
Other [Member]
Net Investment Income [Line Items]
Gross investment income	$ 72	$ 66	$ 71