Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Premiums Earned, Net [Abstract]
Ceded	$ 113	$ 146	$ 249	$ 276
Premiums Earned Net	7,654	7,432	15,400	14,834
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	171	188	335	347
Individual Life Insurance And Annuity Business Sold [Member]
Premiums Earned, Net [Abstract]
Ceded	40	42	81	83
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	66	61	134	147
Other Subsegments [Member]
Premiums Earned, Net [Abstract]
Ceded	73	104	168	193
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	$ 105	$ 127	$ 201	$ 200