Summary Of Information About Securities Sold (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	$ 345,601	$ 236,662	[1]	$ 314,904	[2]
Gross realized gains	40,851	28,249		29,821
Gross realized losses	(2,477)	(24,323)		(13,361)
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	0	0		1
Gross realized gains	0	0		1
Gross realized losses	$ 0	$ 0		$ 0

[1] Includes $12.3 million of unsettled trades

[2] Proceeds from sales including discontinued operations were $326 million in 2010.