Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Preferred Stock, Shares Authorized			2,000,000,000
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		(2,707,000)		(1,120,000)	(657,000)
Common Stock, Shares, Outstanding		114,647,000	111,814,000	114,647,000	119,828,000	119,308,000
Share Repurchase Program Authorized Amount	$ 100,000
Stock Repurchase Program, Additional Amount Authorized		150,000
Treasury Stock, Shares, Acquired		(5,540,000)	(3,245,502)	(6,301,000)	(137,000)
Treasury Stock, Value, Acquired, Cost Method			$ 99,699
Common Stock Issued [Member]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures			(45,000)	(50,000)	(239,000)
Common Stock, Shares, Outstanding		125,337,000	125,382,000	125,337,000	125,287,000	125,048,000
Treasury Stock, Shares, Acquired			0	0	0
Treasury Stock [Member]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures			(2,662,000)	(1,070,000)	(418,000)
Common Stock, Shares, Outstanding		10,690,000	13,568,000	10,690,000	5,459,000	5,740,000
Treasury Stock, Shares, Acquired			(5,540,000)	(6,301,000)	(137,000)