Unaudited Condensed Consolidated Statement of Equity Statement (USD $) In Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Net Unrealized Investment Gain (Loss) [Member]	Noncontrolling Interest [Member]
Balance at beginning of period at Dec. 31, 2009	$ 1,482,788	$ 254,027	$ 1,735,493	$ (10)	$ (603,876)	$ 97,142		$ 12
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net income	71,552	0	0	0	71,197	0		355
Dividends declared on common stock	(20,063)	0	(20,063)	0	0	0		0
Foreign currency translation	(2,506)	0	0	0	0	(2,505)		(1)
Employee share-based compensation earned	4,545	0	4,545	0	0	0		0
Stock option exercises	1,456	386	1,070	0	0	0		0
Tax benefits related to share based awards	875	0	875	0	0	0		0
Restricted stock awards, net of forfeitures	0	532	(532)	0	0	0		0
Purchase of Company common stock	(55,225)	0	(48,935)	(6,290)	0	0		0
Other	552	3	489	60	0	0		0
Balance at end of period at Jun. 30, 2010	1,483,974	254,948	1,672,942	(6,240)	(532,679)	94,637		366
Balance at beginning of period at Dec. 31, 2010	1,479,948	242,020	1,603,112	(985)	(477,459)	112,768		492
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net income	66,667	0	0	0	64,857	0		1,810
Dividends declared on common stock	(23,788)	0	(23,788)	0	0	0		0
Foreign currency translation	9,920	0	0	0	0	9,916	0	4
Employee share-based compensation earned	4,542	0	4,542	0	0	0		0
Stock option exercises	6,862	1,016	5,846	0	0	0		0
Restricted stock awards, net of forfeitures	0	539	(539)	0	0	0		0
Purchase of Company common stock	(55,644)	0	(50,189)	(5,455)	0	0		0
Acquisition	18,857	0	0	0	0	0		18,857
Noncontrolling interest payment	(568)	0	0	0	0	0		(568)
Other	753	72	680	1	0	0		0
Balance at end of period at Jun. 30, 2011	$ 1,507,549	$ 243,647	$ 1,539,664	$ (6,439)	$ (412,602)	$ 122,684		$ 20,595