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			(23,936)
Restricted stock units expensed			12,524
Stock issued to directors			308						564
Net income to common stockholders	197,715			197,774
Dividends				(21,275)
Unrealized gains (losses) on securities not other-than-temporarily impaired					53,342
Unrealized gains on other-than-temporarily impaired securities					(426)
Net change in period	9,853					9,853
Net change in period	1,411						1,411
Stock exercised/vested									37,156
Stock repurchased									(59,159)
Contributions (distributions)										332
Net income (loss)	59									(59)
Other comprehensive income (loss), net of tax	64,192									12
End of period at Mar. 31, 2011
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			(12,092)
Restricted stock units expensed			14,792
Stock issued to directors			454						581
Net income to common stockholders	244,136			244,156
Dividends				(23,482)
Unrealized gains (losses) on securities not other-than-temporarily impaired					60,275
Unrealized gains on other-than-temporarily impaired securities					1,256
Net change in period	(1,674)					(1,674)
Net change in period	1,647						1,647
Stock exercised/vested									23,393
Stock repurchased									(54,878)
Contributions (distributions)										1,524
Net income (loss)	20									(20)
Other comprehensive income (loss), net of tax	61,532									28
End of period at Jun. 30, 2012	$ 4,216,842	$ 47,024	$ 944,263	$ 4,711,836	$ 491,950	$ (62,913)	$ (12,682)	$ 416,355	$ (1,911,694)	$ 9,058