Investments (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Investment Income:
Investment income, before expense	$ 1,001	$ 995	$ 3,070	$ 3,131
Investment expense	(51)	(55)	(153)	(154)
Net investment income	950	940	2,917	2,977
Fixed income securities
Net Investment Income:
Investment income, before expense	721	817	2,223	2,441
Equity securities
Net Investment Income:
Investment income, before expense	30	29	94	74
Mortgage loans
Net Investment Income:
Investment income, before expense	99	92	290	277
Limited partnership interests
Net Investment Income:
Investment income, before expense	106	22	339	238
Short-term investments
Net Investment Income:
Investment income, before expense	1	2	4	4
Other
Net Investment Income:
Investment income, before expense	$ 44	$ 33	$ 120	$ 97