Change in Net Unrealized Gains/(Losses) (Detail) (USD $) In Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Change in unrealized gains (losses) before tax					$ 25,444		$ 21,574
Deferred income tax (charged) credited	(8,390)		(4,162)		(8,573)		(7,354)
Change in net unrealized gains (losses) on investments, net of tax	16,833	[1]	8,222	[1]	16,871	[2]	14,220	[2]
Fixed maturities
Change in unrealized gains (losses) before tax					21,206		26,921
Equity Securities
Change in unrealized gains (losses) before tax					$ 4,238		$ (5,347)

[1] Disclosure of reclassification amount, net of tax: Unrealized gains (losses) on investments arising during period $ 18,385 $ 15,281 Reclassification adjustment for net realized (gains) losses included in net income (1,913 ) 7,163 Reclassification adjustment for other-than-temporary impairment losses recognized in net income 361 (104 ) Change in net unrealized gains (losses) on investments, net of tax $ 16,833 $ 8,222

[2] Disclosure of reclassification amount, net of tax: Unrealized gains (losses) on investments arising during period $ 17,266 $ 25,196 Reclassification adjustment for net realized (gains) losses included in net income (913 ) 11,136 Reclassification adjustment for other-than-temporary impairment losses recognized in net income 518 (160 ) Change in net unrealized gains (losses) on investments, net of tax $ 16,871 $ 14,220