Stock, Stock Options and Rights Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.00%	2.20%	2.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	5 years	4 years 11 months 25 days	4 years 9 months 15 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	63.40%	60.20%	60.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected , Estimated Annualized Forfeiture Rate	5.50%	6.80%	7.50%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.10%	0.10%	0.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 months	6 months	6 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	58.50%	57.40%	56.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected , Estimated Annualized Forfeiture Rate	4.00%	4.00%	4.00%