Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Premiums Earned, Net [Abstract]
Ceded	$ 168	$ 118	$ 444	$ 387
Net	7,347	6,832	22,181	20,308
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	196	168	543	506
Individual Life Insurance And Annuity Business Sold [Member]
Premiums Earned, Net [Abstract]
Ceded	38	38	121	127
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	83	46	230	214
Other Subsegments [Member]
Premiums Earned, Net [Abstract]
Ceded	130	80	323	260
Reinsurance Recoveries [Abstract]
Reinsurance recoveries	$ 113	$ 122	$ 313	$ 292