Invested Assets and Related Income - Components of Unrealized Appreciation or Depreciation of Investments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investments Debt And Equity Securities [Abstract]
Fixed maturities, Gross unrealized appreciation	$ 1,457	$ 2,704
Fixed maturities, Gross unrealized depreciation	325	26
Fixed maturities, Unrealized appreciation (depreciation), Net	1,132	2,678
Equity securities, Gross Unrealized Appreciation	756	453
Equity securities, Gross Unrealized Depreciation	3	34
Equity securities, Unrealized appreciation (depreciation), Net	753	419
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net	1,885	3,097
Deferred income tax liability	660	1,084
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax	$ 1,225	$ 2,013