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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net premiums earned	$ 7,405	$ 4,360	$ 14,002	$ 8,287
Policy benefits and other reserve adjustments	146	153	272	295
Net realized gains (losses)	(216)	126	(610)	37
Guaranteed Minimum Death Benefit [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net premiums earned	13	16	27	32
Policy benefits and other reserve adjustments	15	11	23	20
Guaranteed Living Benefit [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net premiums earned	31	30	60	62
Policy benefits and other reserve adjustments	4	7	15	19
Net realized gains (losses)	(137)	104	(371)	59
Loss recognized in Net income	(110)	127	(326)	102
Less: Net cash received	24	26	42	54
Net (increase) decrease in liability	$ (134)	$ 101	$ (368)	$ 48