Investments (Realized Investment Gains Losses Net) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ 1,433	$ 129	$ 3,314	$ 2,490
Fixed maturities
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	433	371	360	840
Equity securities
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	71	227	99	348
Commercial mortgage and other loans
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	4	20	31	31
Investment real estate
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	1	14	1	38
Joint ventures and limited partnerships
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(23)	(4)	(64)	(9)
Derivatives
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	951	(503)	2,895	1,235
Other
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ (4)	$ 4	$ (8)	$ 7