Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common stocks	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Income	Unrealized Investment gains (losses)	Currency translation adjustments	Net pension asset	Treasury Stock	Noncontrolling Interests
Beginning of period at Dec. 31, 2011		$ 47,024	$ 941,109	$ 4,491,162		$ 430,419	$ (61,239)	$ (14,329)	$ (1,880,790)	$ 7,526
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised and restricted units issued including tax benefit			(22,125)
Restricted stock units expensed			25,728
Stock issued			454						581
Net income (loss)	510,643			510,592						51
Dividends				(183,947)
Unrealized gains (losses) on securities not other-than-temporarily impaired	87,316					84,229
Unrealized gains on other-than-temporarily impaired securities						3,010
Net change in period	24,563						24,563
Net change in period	(1,022)							(1,022)
Stock exercised/vested									45,253
Stock repurchased									(134,455)
Acquisition of noncontrolling interest										21,595
Other comprehensive income, net of tax	110,857									77
End of period at Dec. 31, 2012		47,024	945,166	4,817,807	465,631	517,658	(36,676)	(15,351)	(1,969,411)	29,249
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised and restricted units issued including tax benefit			(1,143)
Restricted stock units expensed			22,881
Stock issued			536						597
Net income (loss)	505,301			499,925						5,376
Dividends				(52,717)
Unrealized gains (losses) on securities not other-than-temporarily impaired	(261,064)					(261,791)
Unrealized gains on other-than-temporarily impaired securities						699
Net change in period	(23,848)						(23,848)
Net change in period	8,700							8,700
Stock exercised/vested									2,452
Stock repurchased									(166,473)
Acquisition of noncontrolling interest										(1,294)
Other comprehensive income, net of tax	(276,212)				(276,212)		(23,848)	8,700		28
End of period at Dec. 31, 2013	4,369,394	47,024	967,440	5,265,015	189,391	256,566	(60,524)	(6,651)	(2,132,835)	33,359
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised and restricted units issued including tax benefit			(4,485)
Restricted stock units expensed			27,966
Stock issued			591						594
Net income (loss)	649,603			648,884						719
Dividends				(181,489)
Unrealized gains (losses) on securities not other-than-temporarily impaired	49,666					49,071
Unrealized gains on other-than-temporarily impaired securities						562
Net change in period	(62,125)						(62,125)
Net change in period	6,651							6,651
Stock exercised/vested									6,623
Stock repurchased									(238,933)
Acquisition of noncontrolling interest										78
Other comprehensive income, net of tax	(5,808)				(5,808)		(62,125)	6,651		33
End of period at Dec. 31, 2014	$ 4,624,134	$ 47,024	$ 991,512	$ 5,732,410	$ 183,550	$ 306,199	$ (122,649)	$ 0	$ (2,364,551)	$ 34,189