Stockholders' Equity And Stock-Based Compensation (Schedule Of Weighted Average Grant Date Fair Value Of Purchase Rights Granted Under Employee Stock Purchase Plan) (Details) (Employee Stock Purchase Plan [Member], USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares	940,703	1,011,765	1,257,804
Weighted average fair value	$ 6.56	$ 4.35	$ 3.83