Investments (Schedule Of Fixed Maturities By Contractual Maturity) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Available for sale, Due in 1 year or less, Amortized Cost	$ 2,317	$ 1,887
Available for sale, Due after 1 year through 5 years, Amortized Cost	13,978	13,411
Available for sale, Due after 5 years though 10 years, Amortized Cost	16,291	15,032
Available for sale, Due after 10 years, Amortized Cost	4,601	4,285
Available for sale, Subtotal, Amortized Cost	37,187	34,615
Available for sale, Mortgage-backed securities, Amortized Cost	10,294	10,051
Available for sale, Amortized Cost	47,481	44,666
Available for sale, Fair Value	48,529	47,306
Held to maturity, Due in 1 year or less, Amortized Cost	398	656
Held to maturity, Due after 1 year through 5 years, Amortized Cost	2,335	1,870
Held to maturity, Due after 5 years through 10 years, Amortized Cost	1,707	2,119
Held to maturity, Due after 10 years, Amortized Cost	426	597
Held to maturity, Subtotal, Amortized Cost	4,866	5,242
Held to maturity, Mortgage backed securities, Amortized Cost	1,440	2,028
Available for sale, Due in 1 year or less, Fair Value	2,345	1,906
Available for sale, Due after 1 year through 5 years, Fair Value	14,450	14,010
Available for sale, Due after 5 years through 10 years, Fair Value	16,650	16,153
Available for sale, Due after 10 years, Fair Value	4,705	4,764
Available for sale, Subtotal, Fair Value	38,150	36,833
Available for sale, Mortgage backed securities, Fair Value	10,379	10,473
Held to maturity, Due in 1 year or less, Fair Value	401	659
Held to maturity, Due after 1 year through 5, Fair Value	2,417	1,950
Held to maturity, Due after 5 years through 10 years, Fair Value	1,756	2,267
Held to maturity, Due after 10 years, Fair Value	436	641
Held to maturity, Subtotal, Fair Value	5,010	5,517
Held to maturity, Mortgage backed securities, Fair Value	1,483	2,116
Held-to-maturity Securities	6,306	7,270
Held to maturity, Fair Value	$ 6,493	$ 7,633