Investments - Schedule of Net Change in Unrealized Gains (Losses) Securities Available-for-Sale (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Total net change in unrealized gains on available-for-sale investments	$ (2,556)	$ 1,875	$ 1,437
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total net change in unrealized gains on available-for-sale investments	(2,541)	1,871	1,442
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total net change in unrealized gains on available-for-sale investments	(15)	5	(2)
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Total net change in unrealized gains on available-for-sale investments		$ (1)	$ (3)