Investments - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Gain (Loss) on Investments [Line Items]
Fixed maturities, fair value of hybrid securities	$ 17,000,000	$ 18,000,000
Unrealized losses 12 months or more (equity investment less than $500,000)	19,000,000	5,000,000
Fixed maturity investments, Percentage of amortized costs	70.00%	70.00%
Fixed Maturities
Gain (Loss) on Investments [Line Items]
Number Of Securities Other Than Temporary Impairment Losses	1	7
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months	99	40
Unrealized investment gains due to a net gain position	613,000,000	558,000,000
Unrealized losses 12 months or more (equity investment less than $500,000)	19,000,000	5,000,000
Equity Securities
Gain (Loss) on Investments [Line Items]
Number Of Securities Other Than Temporary Impairment Losses	2
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months	1
Unrealized investment gains due to a net gain position	1,888,000,000	1,856,000,000
Unrealized losses 12 months or more (equity investment less than $500,000)	500,000,000	0
Procter And Gamble Company, Exxon Mobile Corporation And Chevron Corporation [Member]
Gain (Loss) on Investments [Line Items]
Unrealized investment gains due to a net gain position	$ 431,000,000
Common Stock
Gain (Loss) on Investments [Line Items]
Number of securities	5