Invested Assets and Related Income - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013 Investment	Dec. 31, 2012
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	$ 18,670	$ 18,163
Approximate number of individual fixed maturities in unrealized loss position	1,160
Approximate number of individual equity securities in unrealized loss position	10
Cumulative credit-related losses recognized in net income	20	22
U S Government And Government Agencies And Authorities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	802	1,039
Corporate Bond Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	9,314	7,937
Foreign Government Debt [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	6,890	7,008
Supranational Organization Issued [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	$ 547	$ 517