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, 2013										$ 33,359
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued including tax benefit			$ (3,894)
Restricted stock units expensed			27,966
Stock issued									$ 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)
Contributions (distributions)										78
Other comprehensive income (loss), net of tax	(5,808)									33
End of period at Dec. 31, 2014		$ 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]
Restricted stock units issued including tax benefit			(16,748)
Restricted stock units expensed			30,691
Stock issued									623
Net income (loss)	504,107			503,694						413
Dividends				(58,034)
Unrealized gains (losses) on securities not other-than-temporarily impaired	(125,542)					(125,391)
Unrealized gains (losses) on other-than-temporarily impaired securities						(113)
Net change in period	(124,744)						(124,744)
Net change in period	0							0
Stock exercised/vested									23,975
Stock repurchased									(223,652)
Contributions (distributions)										(1,602)
Other comprehensive income (loss), net of tax	(250,286)				(250,286)		(124,744)			(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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued including tax benefit			(3,594)
Restricted stock units expensed			35,585
Stock issued									685
Net income (loss)	603,485			601,916						1,569
Dividends				(183,999)
Unrealized gains (losses) on securities not other-than-temporarily impaired	246,518					246,872
Unrealized gains (losses) on other-than-temporarily impaired securities						(413)
Net change in period	(124,193)						(124,193)
Net change in period	0							0
Stock exercised/vested									6,495
Stock repurchased									(132,392)
Contributions (distributions)										(546)
Other comprehensive income (loss), net of tax	122,325				122,325		(124,193)			(59)
End of period at Dec. 31, 2016	$ 5,081,134	$ 47,024	$ 1,037,446	$ 6,595,987	$ 55,568	$ 427,154	$ (371,586)	$ 0	$ (2,688,817)	$ 33,926