Investments and Derivative Instruments (Details 16) (Cash flow hedges [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Derivative Instruments Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ (38)	$ (66)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		(2)
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	44	39
Interest rate swaps [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(33)	(66)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		(2)
Interest rate swaps [Member] | Net realized capital gains (losses) [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	5	2
Interest rate swaps [Member] | Net investment income (loss) [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	36	32
Foreign currency swaps [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(5)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)
Foreign currency swaps [Member] | Net realized capital gains (losses) [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	$ 3	$ 5