Common Stock (Stock Repurchase Program) (Details) (USD $) In Thousands, except Share data	3 Months Ended		9 Months Ended			155 Months Ended
	Sep. 30, 2011		Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Mar. 21, 2011		Dec. 31, 2010
Shares repurchased	1,591,317		2,502,066			25,125,795	[1]
Cost, including commission (in thousands)	$ 50,954	[2]	$ 77,274	[2]		$ 414,413	[1],[2]
2010 Plan balance at December 31, 2010										676,271
2011 Plan repurchase shares authorized								2,500,000	[3]
Total remaining shares available for repurchase at September 30, 2011	674,205		674,205			674,205
Unsettled repurchase of common stock	$ 12,491		$ 12,491		$ 0

[1] Represents repurchased shares and cost since inception of the stock repurchase program in 1999.

[2] Costs of repurchased shares for the three and nine months ended September 30, 2011 include $12.5 million related to transactions that were not settled as of September 30, 2011.

[3] On March 21, 2011, the Board of Directors authorized an additional repurchase of the Company’s common stock (the “2011 Plan”).