Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Unrealized Investment Gains (Losses) [Member]	Currency Translation Adjustments [Member]	Net Pension Asset [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning of period at Dec. 31, 2011		$ 47,024	$ 941,109	$ 4,491,162	$ 430,419	$ (61,239)	$ (14,329)		$ (1,880,790)	$ 7,526
Stock options exercised and restricted units issued, net of tax			(10,139)
Restricted stock units expensed			7,447
Net income to common stockholders	135,232			135,318
Dividends				(11,041)
Unrealized gains (losses) on securities not other-than-temporarily impaired					20,868
Unrealized gains on other-than-temporarily impaired securities					1,133
Net change in period	15,583					15,583
Net change in period	824						824
Stock exercised/vested									20,099
Stock repurchased									(6,532)
Contributions (distributions)										1,076
Net income (loss)	86									(86)
Other comprehensive income (loss), net of tax	38,431									23
End of period at Mar. 31, 2012		47,024	938,417	4,615,439	452,420	(45,656)	(13,505)	393,259	(1,867,223)	8,539
Beginning of period at Dec. 31, 2012	4,335,466	47,024	945,166	4,817,807	517,658	(36,676)	(15,351)	465,631	(1,969,411)	29,249
Stock options exercised and restricted units issued, net of tax			(233)
Restricted stock units expensed			4,993
Net income to common stockholders	116,598			116,615
Dividends				(12,244)
Unrealized gains (losses) on securities not other-than-temporarily impaired					7,047
Unrealized gains on other-than-temporarily impaired securities					723
Net change in period	(46,623)					(46,623)
Net change in period	1,814						1,814	(11,365)
Stock exercised/vested									232
Stock repurchased									0
Contributions (distributions)										2,817
Net income (loss)	17									(17)
Other comprehensive income (loss), net of tax	(36,999)				7,810	(46,623)	1,814	(36,999)		40
End of period at Mar. 31, 2013	$ 4,410,630	$ 47,024	$ 949,926	$ 4,922,178	$ 525,428	$ (83,299)	$ (13,537)	$ 428,592	$ (1,969,179)	$ 32,089