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 [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]
Beginning of period at Dec. 31, 2010		$ 47,024	$ 935,099	$ 4,143,207	$ 334,747	$ (42,488)	$ (15,696)		$ (1,750,494)	$ 6,980
Stock options exercised and restricted units issued, net of tax			(15,977)
Restricted stock units expensed			6,468
Net income to common stockholders	115,595			115,590
Dividends				(9,913)
Unrealized gains (losses) on securities not other-than-temporarily impaired					(25,110)
Unrealized gains on other-than-temporarily impaired securities					159
Net change in period	10,860					10,860
Net change in period	704						704
Stock exercised/vested									28,533
Stock repurchased									(23,303)
Contributions (distributions)										264
Net income (loss)	(5)									5
Other comprehensive income (loss), net of tax	(13,443)									(56)
End of period at Mar. 31, 2011		47,024	925,590	4,248,884	309,796	(31,628)	(14,992)	263,176	(1,745,264)	7,193
Beginning of period at Dec. 31, 2011	3,960,882	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	$ 4,135,455	$ 47,024	$ 938,417	$ 4,615,439	$ 452,420	$ (45,656)	$ (13,505)	$ 393,259	$ (1,867,223)	$ 8,539