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			(6,383)
Stock incentive plans expensed			21,047
Net income before noncontrolling interests	$ 538,652			538,173						479
Dividends				(40,782)
Change in unrealized investment gains (losses), net of taxes	108,232				107,501
Unrealized gains on other-than-temporarily impaired securities					612
Change in unrealized currency translation adjustments	(28,590)					(28,590)
Change in net pension asset, net of taxes	4,631						4,631
Stock exercised/vested									6,384
Stock repurchased									(230,319)
Stock or Unit Option Plan Expense	594
Contributions (distributions)										614
Other comprehensive income (loss)	84,273					(28,590)	4,631	$ 84,273		119
End of period at Sep. 30, 2014			982,104	5,762,406	364,679	(89,114)	(2,020)	273,545	(2,356,176)	34,571
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			(25,394)
Stock incentive plans expensed			23,429
Net income before noncontrolling interests	394,229			393,949						280
Dividends				(43,239)
Change in unrealized investment gains (losses), net of taxes	(78,832)				(78,773)
Unrealized gains on other-than-temporarily impaired securities					47
Change in unrealized currency translation adjustments	(76,713)					(76,713)
Change in net pension asset, net of taxes	0						0
Stock exercised/vested									23,044
Stock repurchased									(223,652)
Stock or Unit Option Plan Expense	623
Contributions (distributions)										(992)
Other comprehensive income (loss)	(155,545)					(76,713)	0	(155,545)		(106)
End of period at Sep. 30, 2015	$ 4,616,637		$ 989,547	$ 6,083,120	$ 227,473	$ (199,362)	$ 0	$ 28,111	$ (2,564,536)	$ 33,371