Derivatives (Earned Income On Derivatives) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	$ 179	$ 257	$ 616	$ 717
Derivatives Designated as Hedging Instruments: | Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	72	71	217	192
Derivatives Designated as Hedging Instruments: | Interest credited to policyholder account balances
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	(19)	0	(40)	7
Derivatives Designated as Hedging Instruments: | Other expenses
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	(2)	(3)	(7)	(9)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	0	0	0	(1)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	126	187	440	522
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	$ 2	$ 2	$ 6	$ 6