Investments (Details 3) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Investment Income:
Investment income, before expense	$ 790	$ 842	$ 2,368	$ 2,557
Investment expense	(42)	(35)	(127)	(111)
Net investment income	748	807	2,241	2,446
Fixed income securities
Net Investment Income:
Investment income, before expense	508	546	1,546	1,681
Equity securities
Net Investment Income:
Investment income, before expense	31	23	103	77
Mortgage loans
Net Investment Income:
Investment income, before expense	56	53	162	165
Limited partnership interests
Net Investment Income:
Investment income, before expense	136	167	383	483
Short-term investments
Net Investment Income:
Investment income, before expense	4	4	11	8
Other
Net Investment Income:
Investment income, before expense	$ 55	$ 49	$ 163	$ 143