Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts (Schedule Of Guaranteed Minimum Benefits Income And Expense) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net premiums earned	$ 7,688	$ 4,719	$ 21,690	$ 13,006
Policy benefits and other reserve adjustments	155	89	427	384
Net realized gains (losses)	100	(397)	(510)	(360)
Guaranteed Minimum Death Benefit [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net premiums earned	15	15	42	47
Policy benefits and other reserve adjustments	11	5	34	25
Guaranteed Minimum Income Benefit [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net premiums earned	28	30	88	92
Policy benefits and other reserve adjustments	9	15	24	34
Net realized gains (losses)	86	(397)	(285)	(338)
Loss recognized in Net income	105	(382)	(221)	(280)
Less: Net cash received	15	20	57	74
Net (increase) decrease in liability	$ 90	$ (402)	$ (278)	$ (354)