Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Income and Comprehensive Income [Abstract]
Net earnings	$ 97,136	$ 88,162	$ 205,047	$ 194,012
Investment gains (losses):
Investment gains (losses) during the period	93,745	(217,034)	179,825	(247,429)
Income tax charge (benefit)	33,248	(77,116)	63,818	(87,443)
Investments gains (losses), net of tax	60,497	(139,918)	116,007	(159,986)
Less reclassification adjustments to:
Net realized investment gain	4,905	4,623	25,151	13,193
Income tax expense	1,717	1,619	8,803	4,618
Total reclassifications included in net earnings, net of tax	3,188	3,004	16,348	8,575
Net unrealized investment gains (losses)	57,309	(142,922)	99,659	(168,561)
Foreign currency translation adjustment	903	911	1,691	(1,145)
Income tax charge (benefit)	11	(30)	(421)	(554)
Foreign currency translation adjustment, net of tax	892	941	2,112	(591)
Other comprehensive income (loss)	58,201	(141,981)	101,771	(169,152)
Comprehensive income	$ 155,337	$ (53,819)	$ 306,818	$ 24,860