Derivatives (Fair Value Hedges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivatives Gains (Losses) Recognized for Derivatives	$ (280)	$ (293)
Net Derivatives Gains (Losses) Recognized for Hedged Items	272	286
Ineffectiveness Recognized in Net Derivatives Gains (Losses)	(8)	(7)
Interest rate swaps [Member] | Fixed maturity securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivatives Gains (Losses) Recognized for Derivatives	8	6
Net Derivatives Gains (Losses) Recognized for Hedged Items	(8)	(6)
Ineffectiveness Recognized in Net Derivatives Gains (Losses)	0	0
Interest rate swaps [Member] | Policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivatives Gains (Losses) Recognized for Derivatives	(153)	(300)
Net Derivatives Gains (Losses) Recognized for Hedged Items	152	301
Ineffectiveness Recognized in Net Derivatives Gains (Losses)	(1)	1
Foreign currency swaps [Member] | Foreign-denominated fixed maturity securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivatives Gains (Losses) Recognized for Derivatives	4	2
Net Derivatives Gains (Losses) Recognized for Hedged Items	(5)	(2)
Ineffectiveness Recognized in Net Derivatives Gains (Losses)	(1)	0
Foreign currency swaps [Member] | Foreign-denominated policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivatives Gains (Losses) Recognized for Derivatives	(139)	57
Net Derivatives Gains (Losses) Recognized for Hedged Items	133	(63)
Ineffectiveness Recognized in Net Derivatives Gains (Losses)	(6)	(6)
Foreign currency forwards [Member] | Foreign-denominated fixed maturity securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivatives Gains (Losses) Recognized for Derivatives	0	(58)
Net Derivatives Gains (Losses) Recognized for Hedged Items	0	56
Ineffectiveness Recognized in Net Derivatives Gains (Losses)	$ 0	$ (2)