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			(26,914)
Restricted stock units expensed			18,855
Stock issued to directors			308						564
Net income to common stockholders	274,086			274,184
Dividends				(32,274)
Unrealized gains on securities not other-than-temporarily impaired					79,435
Unrealized gains (losses) on other-than-temporarily impaired securities					(1,271)
Net change in period	(21,104)					(21,104)
Net change in period	2,118						2,118
Stock exercised/vested									40,571
Stock repurchased									(177,648)
Contributions										522
Net loss (income)	98									(98)
Other comprehensive income, net of tax	59,189									11
End of period at Sep. 30, 2011		47,024	927,348	4,385,117	412,911	(63,592)	(13,578)	335,741	(1,887,007)	7,415
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			(24,683)
Restricted stock units expensed			20,035
Stock issued to directors			454						581
Net income to common stockholders	345,144			345,103
Dividends				(35,728)
Unrealized gains on securities not other-than-temporarily impaired					123,579
Unrealized gains (losses) on other-than-temporarily impaired securities					2,870
Net change in period	24,382					24,382
Net change in period	2,470						2,470
Stock exercised/vested									40,137
Stock repurchased									(128,155)
Contributions										1,808
Net loss (income)	(41)									41
Other comprehensive income, net of tax	153,372									71
End of period at Sep. 30, 2012	$ 4,333,847	$ 47,024	$ 936,915	$ 4,800,537	$ 556,868	$ (36,857)	$ (11,859)	$ 508,152	$ (1,968,227)	$ 9,446