Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Premiums Earned, Net [Abstract]
Ceded	$ 146	$ 128	$ 276	$ 269
Net	7,432	6,800	14,834	13,476
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	188	157	347	338
Individual Life Insurance And Annuity Business Sold [Member]
Premiums Earned, Net [Abstract]
Ceded	42	44	83	89
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	61	69	147	168
Other Subsegments [Member]
Premiums Earned, Net [Abstract]
Ceded	104	84	193	180
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	$ 127	$ 88	$ 200	$ 170