Investments (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net Investment Income:
Investment income, before expense	$ 999	$ 1,031
Investment expense	(40)	(48)
Net investment income	959	983
Fixed income securities
Net Investment Income:
Investment income, before expense	705	762
Equity securities
Net Investment Income:
Investment income, before expense	28	25
Mortgage loans
Net Investment Income:
Investment income, before expense	81	98
Limited partnership interests
Net Investment Income:
Investment income, before expense	142	107
Short-term investments
Net Investment Income:
Investment income, before expense	1	2
Other
Net Investment Income:
Investment income, before expense	$ 42	$ 37