Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Premiums Earned, Net [Abstract]
Ceded	$ 131	$ 168	$ 380	$ 444
Premiums Earned Net	7,605	7,347	23,005	22,181
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	85	196	420	543
Individual Life Insurance And Annuity Business Sold [Member]
Premiums Earned, Net [Abstract]
Ceded	37	38	118	121
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	77	83	211	230
Other Subsegments [Member]
Premiums Earned, Net [Abstract]
Ceded	94	130	262	323
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	$ 8	$ 113	$ 209	$ 313