Investments and Derivative Instruments (Details 16) (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]
Document Period End Date			Sep. 30, 2012
Cash flow hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 40	$ 263	$ 154	$ 345
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		(3)		(5)
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	41	28	113	103
Interest Rate Swap [Member] | Cash flow hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	42	263	185	345
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		(3)		(5)
Interest Rate Swap [Member] | Net realized capital gains (losses) [Member] | Cash flow hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	4	4	10	8
Interest Rate Swap [Member] | Net Investment Income [Member] | Cash flow hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	36	33	110	96
Foreign Currency Swap [Member] | Cash flow hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(2)		(31)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)
Foreign Currency Swap [Member] | Net realized capital gains (losses) [Member] | Cash flow hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	$ 1	$ (9)	$ (7)	$ (1)