Investments and Derivative Instruments (Details 16) (Cash Flow Hedging [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 20	$ 207	$ 64	$ 251
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	0	(2)	0	(2)
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	28	15	75	67
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	21	211	82	253
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	0	(2)	0	(2)
Interest Rate Swap [Member] | Net realized capital gains (losses) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	1	4	5	6
Interest Rate Swap [Member] | Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	26	20	77	59
Foreign Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(1)	(4)	(18)	(2)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	0	0	0	0
Foreign Currency Swap [Member] | Net realized capital gains (losses) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	$ 1	$ (9)	$ (7)	$ 2