Consolidated Statements of Stockholders' Equity Statement (USD $) In Thousands, unless otherwise specified	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, 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]
Options exercised and restricted stock units issued, net of tax			(233)
Restricted stock units expensed			4,993
Net income before noncontrolling interests	116,598			116,615						(17)
Dividends				(12,244)
Change in unrealized investment gains, net of taxes	7,810				7,047
Unrealized gains on other-than-temporarily impaired securities					723
Change in unrealized currency translation adjustments	(46,623)					(46,623)
Change in net pension asset, net of taxes	1,814						1,814
Stock exercised/vested									232
Stock repurchased									0
Contributions										2,817
Other comprehensive income (loss)	(36,999)					(46,623)	1,814	(36,999)		40
End of period at Mar. 31, 2013			949,926	4,922,178	525,428	(83,299)	(13,537)		(1,969,179)	32,089
Beginning and end of period at Dec. 31, 2013	4,369,394	47,024	967,440	5,265,015	256,566	(60,524)	(6,651)	428,592	(2,132,835)	33,359
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Options exercised and restricted stock units issued, net of tax			(3,338)
Restricted stock units expensed			6,203
Net income before noncontrolling interests	169,684			169,673						11
Dividends				(12,775)
Change in unrealized investment gains, net of taxes	72,944				72,563
Unrealized gains on other-than-temporarily impaired securities					363
Change in unrealized currency translation adjustments	(4,025)					(4,025)
Change in net pension asset, net of taxes	591						591
Stock exercised/vested									3,322
Stock repurchased									(192,668)
Contributions										1,526
Other comprehensive income (loss)	69,510					(4,025)	591	69,510		18
End of period at Mar. 31, 2014	$ 4,410,858		$ 970,305	$ 5,421,913	$ 329,492	$ (64,549)	$ (6,060)	$ 258,883	$ (2,322,181)	$ 34,914