Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	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, 2012		$ 47,024	$ 945,166	$ 4,817,807		$ 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 (losses) 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 (sale) of noncontrolling interest										(1,294)
Other comprehensive income, net of tax	(276,212)									28
End of period at Dec. 31, 2013		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 (losses) 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 (sale) 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised and restricted units issued including tax benefit			(17,456)
Restricted stock units expensed			30,691
Stock issued			708						623
Net income (loss)	504,107			503,694						413
Dividends				(58,034)
Unrealized gains (losses) on securities not other-than-temporarily impaired	(125,542)					(113)
Unrealized gains (losses) on other-than-temporarily impaired securities						(125,391)
Net change in period	(124,744)						(124,744)
Net change in period	0							0
Stock exercised/vested									23,975
Stock repurchased									(223,652)
Acquisition (sale) of noncontrolling interest										(1,602)
Other comprehensive income, net of tax	(250,286)				(250,286)		(124,744)	0		(38)
End of period at Dec. 31, 2015	$ 4,633,208	$ 47,024	$ 1,005,455	$ 6,178,070	$ (66,698)	$ 180,695	$ (247,393)	$ 0	$ (2,563,605)	$ 32,962