Derivatives (Fair Value Hedges) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	$ 501	$ (64)
Net Derivative Gains (Losses) Recognized for Hedged Items	(492)	62
Ineffectiveness Recognized in Net Derivative Gains (Losses)	9	(2)
Interest rate swaps | Fixed Maturity Securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(8)	(5)
Net Derivative Gains (Losses) Recognized for Hedged Items	7	7
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(1)	2
Interest rate swaps | Policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	346	197
Net Derivative Gains (Losses) Recognized for Hedged Items	(348)	(198)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(2)	(1)
Foreign currency swaps | Foreign-denominated fixed maturity securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(1)	10
Net Derivative Gains (Losses) Recognized for Hedged Items	2	(8)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	1	2
Foreign currency swaps | Foreign-denominated policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	25	(249)
Net Derivative Gains (Losses) Recognized for Hedged Items	(25)	245
Ineffectiveness Recognized in Net Derivative Gains (Losses)	0	(4)
Foreign currency forwards | Foreign-denominated fixed maturity securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	139	(17)
Net Derivative Gains (Losses) Recognized for Hedged Items	(128)	16
Ineffectiveness Recognized in Net Derivative Gains (Losses)	$ 11	$ (1)