Summary Of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary Of Significant Accounting Policies [Line Items]
Recognized income tax positions largest amount likely of being realized	50.00%
Stock options to purchase common stock	2,043,774	2,020,767	2,852,161
Shares excluded from the computation of the diluted net income per weighted-average common share	1,116,106	1,179,840	2,052,132
Advertising expense	$ 1.4	$ 1.0	$ 2.3
Equity Method Investments [Member]
Summary Of Significant Accounting Policies [Line Items]
Ownership interest	50.00%
Cost Method Investments [Member]
Summary Of Significant Accounting Policies [Line Items]
Ownership interest	20.00%