Accumulated Other Comprehensive Income (Loss) (Details) - Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Before tax amount:
Unrealized gains (losses) on investments arising during the year	$ 985,543	$ 384,495	$ 968,891
Less reclassification for (losses) realized in income	14,098	(188,359)	(270,803)
Net unrealized gains (losses) on investments	971,445	572,854	1,239,694
Change in value of cash flow hedge	439	439	439
Change in net unrealized gain on future policy benefit reserves			(3,714)
Change in underfunded pension liability	(9,985)	(2,622)	(2,619)
Foreign currency translation adjustments	(6,448)	(25,598)	54,641
Change in other comprehensive income	955,451	545,073	1,288,441
Tax (benefit) expense:
Unrealized gains (losses) on investments arising during the year	(7,348)	51,775	36,122
Less reclassification for (losses) realized in income	(24,137)	(9,927)	(5,369)
Net unrealized gains (losses) on investments	16,789	61,702	41,491
Foreign currency translation adjustments	1,715	1,102	3,688
Change in other comprehensive income	18,504	62,804	45,179
Net of tax amount:
Unrealized gains (losses) arising during year	992,891	332,720	932,769
Less reclassification for (losses) realized in income	38,235	(178,432)	(265,434)
Net unrealized gains (losses) on investments	954,656	511,152	1,198,203
Change in value of cash flow hedge	439	439	439
Change in net unrealized gain (loss) on future policy benefit reserves	0	0	(3,714)
Change in underfunded pension liability	(9,985)	(2,622)	(2,619)
Foreign currency translation adjustments	(8,163)	(26,700)	50,953
Change in other comprehensive income	$ 936,947	$ 482,269	$ 1,243,262