Investments (Details 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Investment Income:
Investment income, before expense	$ 803	$ 825	$ 1,578	$ 1,715
Investment expense	(41)	(36)	(85)	(76)
Net investment income	762	789	1,493	1,639
Fixed income securities
Net Investment Income:
Investment income, before expense	520	567	1,038	1,135
Equity securities
Net Investment Income:
Investment income, before expense	44	31	72	54
Mortgage loans
Net Investment Income:
Investment income, before expense	53	57	106	112
Limited partnership interests
Net Investment Income:
Investment income, before expense	126	118	247	316
Short-term investments
Net Investment Income:
Investment income, before expense	3	3	7	4
Other
Net Investment Income:
Investment income, before expense	$ 57	$ 49	$ 108	$ 94