Consolidated Statements of Stockholders' Equity Statement - USD ($) $ in Thousands	Total	Common stocks	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Accumulated Translation Adjustment [Member]	Accumulated Defined Benefit Plans Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning and end of period at Dec. 31, 2013		$ 47,024	$ 967,440	$ 5,265,015	$ 256,566	$ (60,524)	$ (6,651)		$ (2,132,835)	$ 33,359
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued, net of tax			(5,692)
Stock incentive plans expensed			13,046
Net income before noncontrolling interests	$ 349,861			349,634						227
Dividends				(26,825)
Change in unrealized investment gains (loss), net of taxes	121,144				120,618
Unrealized gains on other-than-temporarily impaired securities					489
Change in unrealized currency translation adjustments	20,790					20,790
Change in net pension asset, net of taxes	2,611						2,611
Stock exercised/vested									5,667
Stock repurchased									(197,254)
Stock or Unit Option Plan Expense	594
Contributions (distributions)										1,222
Other comprehensive income (loss)	144,545					20,790	2,611	$ 144,545		37
End of period at Jun. 30, 2014			974,794	5,587,824	377,673	(39,734)	(4,040)	333,899	(2,323,828)	34,845
Beginning and end of period at Dec. 31, 2014	4,624,134	$ 47,024	991,512	5,732,410	306,199	(122,649)	0		(2,364,551)	34,189
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued, net of tax			(2,295)
Stock incentive plans expensed			14,350
Net income before noncontrolling interests	241,493			241,342						151
Dividends				(28,447)
Change in unrealized investment gains (loss), net of taxes	(83,329)				(83,332)
Unrealized gains on other-than-temporarily impaired securities					15
Change in unrealized currency translation adjustments	(14,178)					(14,178)
Change in net pension asset, net of taxes	0						0
Stock exercised/vested									2,296
Stock repurchased									(218,132)
Stock or Unit Option Plan Expense	623
Contributions (distributions)										(183)
Other comprehensive income (loss)	(97,507)					(14,178)	0	(97,507)		(12)
End of period at Jun. 30, 2015	$ 4,536,332		$ 1,003,567	$ 5,945,305	$ 222,882	$ (136,827)	$ 0	$ 86,055	$ (2,579,764)	$ 34,145