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
	Mar. 31, 2016	Mar. 31, 2015
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	$ 6,597	$ 3,927
Policy benefits and other reserve adjustments	126	142
Net realized gains (losses)	(394)	(89)
Guaranteed Minimum Death Benefit [Member]
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	14	16
Policy benefits and other reserve adjustments	8	9
Guaranteed Living Benefit [Member]
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	29	32
Policy benefits and other reserve adjustments	11	12
Net realized gains (losses)	(234)	(45)
Loss recognized in Net income	(216)	(25)
Less: Net cash received	18	28
Net increase in liability	$ (234)	$ (53)