Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 510,643	$ 391,141	$ 446,684
Other comprehensive income (loss):
Change in unrealized foreign exchange gains (losses)	24,563	(18,751)	(2,117)
Unrealized holding gains on investment securities arising during the period, net of taxes	224,118	177,264	152,235
Reclassification adjustment for net investment gains (losses) included in net income, net of taxes	(136,802)	(81,647)	(36,874)
Change in unrecognized pension obligation, net of taxes	(1,022)	1,367	120
Other comprehensive income	110,857	78,233	113,364
Comprehensive income	621,500	469,374	560,048
Comprehensive income (loss) to the noncontrolling interest	(128)	125	(287)
Comprehensive income to common shareholders	$ 621,372	$ 469,499	$ 559,761