Investments and Derivative Instruments (Details 16) (Cash Flow Hedging [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	$ 75
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(42)	(28)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	0	0
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)	64	4
Interest Rate Swap [Member] | Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	14	25
Foreign Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	1	(3)
Net Realized Capital Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	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)	$ (3)	$ 2