Investments (Details 4) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 81	$ 24	$ 215	$ (125)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	32	24	37	(47)
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	19	11	125	(79)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains and losses	0	1	0	1
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	31	(13)	71	13
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	(8)	2	(23)	(7)
Other
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 7	$ (1)	$ 5	$ (6)