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
Components of Stockholders' Equity [Line Items]
Total number of shares repurchased	900,000	2,606,000
Dollar amount of shares repurchased	$ 199,666	$ 210,259
Average price paid per share	$ 221.88	$ 80.67
Minimum [Member]
Components of Stockholders' Equity [Line Items]
Average price paid per share	$ 160.11	$ 60.23
Maximum [Member]
Components of Stockholders' Equity [Line Items]
Average price paid per share	$ 248.78	$ 126.01