Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Income and Comprehensive Income [Abstract]
Net earnings	$ 88,162	$ 93,493	$ 194,012	$ 176,077
Investment gains (losses):
Investment gains (losses) during the period	(217,034)	39,673	(247,429)	61,313
Income tax charge (benefit)	(77,116)	14,501	(87,443)	21,804
Investments gains (losses), net of tax	(139,918)	25,172	(159,986)	39,509
Less reclassification adjustments for:
Gains included in net earnings	4,623	6,488	13,193	6,659
Income tax charge	1,619	2,271	4,618	2,331
Gains included in net earnings, net of tax	3,004	4,217	8,575	4,328
Net unrealized investment gains (losses)	(142,922)	20,955	(168,561)	35,181
Foreign currency translation adjustment	911	(5,846)	(1,145)	(3,313)
Income tax benefit	(30)	(372)	(554)	(249)
Foreign currency translation adjustment, net of tax	941	(5,474)	(591)	(3,064)
Other comprehensive income (loss)	(141,981)	15,481	(169,152)	32,117
Comprehensive income (loss)	$ (53,819)	$ 108,974	$ 24,860	$ 208,194