Significant Customers And Concentration Of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Concentration Risk [Line Items]
Percentage of quantitative radio ratings services and related software to total revenue	88.00%	88.00%	88.00%
Customer One [Member]
Concentration Risk [Line Items]
Percentage of accounts receivable from one customer out of total accounts receivable	23.00%	24.00%
Customer Two [Member]
Concentration Risk [Line Items]
Percentage of accounts receivable from one customer out of total accounts receivable	11.00%	11.00%
Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Percentage of revenue from one customer out of total revenue	19.00%	20.00%	19.00%