Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Fixed Maturities security	Jun. 30, 2014 Fixed Maturities security	Jun. 30, 2013 Fixed Maturities security	Dec. 31, 2013 Fixed Maturities security	Jun. 30, 2014 Equity Securities security	Jun. 30, 2014 Equity Securities security	Dec. 31, 2013 Equity Securities	Jun. 30, 2014 Procter And Gamble Company, Exxon Mobile Corporation And Chevron Corporation [Member]	Jun. 30, 2014 Common Stock
Gain (Loss) on Investments [Line Items]
Number Of Securities Other Than Temporary Impairment Losses1			0	1	7		1	3
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months			247	247		40	4	4
Number of securities											7
Unrealized investment gains due to a net gain position			$ 686	$ 686		$ 558	$ 2,027	$ 2,027	$ 1,856	$ 599
Fixed maturities, fair value of hybrid securities	7	18
Unrealized losses 12 months or more (equity investment less than $500,000)	$ 25	$ 5	$ 21	$ 21		$ 5	$ 4	$ 4	$ 0
Fixed maturity investments, Percentage of amortized costs	70.00%	70.00%