Stockholders' Equity (Summary Of Stock Repurchases) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Components of Stockholders' Equity [Line Items]
Total number of shares repurchased	900,000	2,606,000	7,371,000
Dollar amount of shares repurchased	$ 199,666	$ 210,259	$ 324,335
Average price paid per share	$ 221.88	$ 80.67	$ 44.00
Maximum [Member]
Components of Stockholders' Equity [Line Items]
Average price paid per share	$ 248.78	$ 126.01	$ 60.00
Minimum [Member]
Components of Stockholders' Equity [Line Items]
Average price paid per share	$ 160.11	$ 60.23	$ 34.70