Derivatives (Earned Income On Derivatives) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	$ 199	$ 179	$ 587	$ 616
Derivatives Designated as Hedging Instruments: | Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	85	72	259	217
Derivatives Designated as Hedging Instruments: | Interest credited to policyholder account balances
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	(28)	(19)	(79)	(40)
Derivatives Designated as Hedging Instruments: | Other expenses
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	(2)	(2)	(8)	(7)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	141	126	407	440
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income (Expense), Nonoperating, Net	$ 3	$ 2	$ 8	$ 6