Change in Net Unrealized Gains/(Losses) (Detail) (USD $) In Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Gross unrealized gains (losses)					$ 24,611		$ 58,484
Deferred income tax charge (credit)	(322)		12,806		8,251		20,160
Change in net unrealized gains (losses) on investments, net of tax	(511)	[1]	24,104	[1]	16,360	[2]	38,324	[2]
Fixed maturities
Gross unrealized gains (losses)					32,898		54,257
Equity Securities
Gross unrealized gains (losses)					$ (8,287)		$ 4,227

[1] Disclosure of reclassification amount, net of tax: Unrealized gains (losses) on investments arising during period $ 411 $ 26,588 Reclassification adjustment for net realized gains (losses) included in net income (1,025 ) (2,939 ) Reclassification adjustment for other-than-temporary impairment losses recognized in net income 103 455 Change in net unrealized gains (losses) on investments, net of tax $ (511 ) $ 24,104

[2] Disclosure of reclassification amount, net of tax: Unrealized gains (losses) on investments arising during period $ 15,986 $ 51,784 Reclassification adjustment for net realized gains (losses) included in net income 264 (14,075 ) Reclassification adjustment for other-than-temporary impairment losses recognized in net income 110 615 Change in net unrealized gains (losses) on investments, net of tax $ 16,360 $ 38,324