Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Statement of Income and Comprehensive Income [Abstract]
Net earnings	$ 255,243	$ 345,096	$ 353,868
Investment gains (losses)
Investment gains (losses) during the year	195,395	(9,873)	147,166
Income tax charge (benefit)	65,618	(3,098)	53,909
Investments gains (losses), net of tax	129,777	(6,775)	93,257
Gains (losses) included in net earnings	(1,022)	11,784	5,483
Income tax charge (benefit)	(358)	4,124	1,920
Gains (losses) included in net earnings, net of tax	(664)	7,660	3,563
Net unrealized investment gains (losses)	130,441	(14,435)	89,694
Cash flow hedge gain (loss)	0	0	8,031
Income tax charge (benefit)	0	0	2,811
Cash flow hedge gain (loss), net of tax	0	0	5,220
Foreign currency translation adjustment	(1,740)	(9,248)	5,190
Income tax charge (benefit)	(1,772)	(1,204)	3,674
Foreign currency translation adjustment, net of tax	32	(8,044)	1,516
Other comprehensive income (loss)	130,473	(22,479)	96,430
Comprehensive income	$ 385,716	$ 322,617	$ 450,298