Investments (Schedule Of Fixed Maturities By Contractual Maturity) (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Available for sale, Due in 1 year or less, Amortized Cost	$ 1,979	$ 2,187
Available for sale, Due after 1 year through 5 years, Amortized Cost	16,472	15,444
Available for sale, Due after 5 years though 10 years, Amortized Cost	13,695	15,663
Available for sale, Due after 10 years, Amortized Cost	4,407	4,521
Available for sale, Subtotal, Amortized Cost	36,553	37,815
Available for sale, Mortgage-backed securities, Amortized Cost	10,858	10,011
Available for sale, Amortized Cost	47,411	47,826
Available for sale, Fair Value	48,278	49,395
Held to maturity, Due in 1 year or less, Amortized Cost	411	353
Held to maturity, Due after 1 year through 5 years, Amortized Cost	2,583	2,603
Held to maturity, Due after 5 years through 10 years, Amortized Cost	2,278	1,439
Held to maturity, Due after 10 years, Amortized Cost	1,534	953
Held to maturity, Subtotal, Amortized Cost	6,806	5,348
Held to maturity, Mortgage backed securities, Amortized Cost	1,758	1,983
Available for sale, Due in 1 year or less, Fair Value	1,995	2,206
Available for sale, Due after 1 year through 5 years, Fair Value	16,794	15,857
Available for sale, Due after 5 years through 10 years, Fair Value	13,708	16,089
Available for sale, Due after 10 years, Fair Value	4,662	4,957
Available for sale, Subtotal, Fair Value	37,159	39,109
Available for sale, Mortgage backed securities, Fair Value	11,119	10,286
Held to maturity, Due in 1 year or less, Fair Value	413	355
Held to maturity, Due after 1 year through 5, Fair Value	2,683	2,693
Held to maturity, Due after 5 years through 10 years, Fair Value	2,300	1,489
Held to maturity, Due after 10 years, Fair Value	1,537	1,013
Held to maturity, Subtotal, Fair Value	6,933	5,550
Held to maturity, Mortgage backed securities, Fair Value	1,817	2,039
Held to maturity, Amortized Cost	8,564	7,331
Held to maturity, Fair Value	$ 8,750	$ 7,589