Components of the Gain or Loss on Derivatives that Qualified as Cash Flow Hedges (Detail) (Cash flow hedges, USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	$ 17	$ 8	$ (38)	$ (2)
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	2	3	(2)	0
Interest rate swaps
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	0	0	1	1
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	0	0	0	0
Foreign currency swaps
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	17	8	(39)	(3)
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	$ 2	$ 3	$ (2)	$ 0