Fair Values of Financial Instruments - Carrying Values and Fair Values of Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	$ 2,114	$ 2,528
Fixed maturities	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets	1,598	1,954
Long Term Debt	3,300	3,575
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	2,114	2,528
Fixed maturities	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets		46
Long Term Debt	3,300	3,575
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	2,114	2,528
Fixed maturities	37,091	38,076
Equity securities	1,810	1,663
Other Invested Assets		46
Long Term Debt	$ 3,806	$ 4,372