Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts (Schedule Of Guaranteed Minimum Benefits Income And Expense) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	$ 3,783	$ 3,757	$ 7,164	$ 7,066
Policy benefits and other reserve adjustments	102	108	249	199
Net realized gains (losses)	(394)	(73)	(134)	(118)
Guaranteed Minimum Death Benefit [Member]
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	21	25	44	51
Policy benefits and other reserve adjustments	12	21	39	43
Guaranteed Minimum Income Benefit [Member]
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	40	41	81	82
Policy benefits and other reserve adjustments	16	6	23	12
Net realized gains (losses)	(494)	(75)	(34)	(17)
(Loss) gain recognized in income	(470)	(40)	24	53
Net cash received	38	40	79	81
Net increase in liability	$ (508)	$ (80)	$ (55)	$ (28)