Quantitative Radio Audience Ratings Service And Related Software Licensing Revenue Accounted Aggregate Percentages Of Total Company Revenue (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Concentration Risk [Abstract]
Quantitative radio audience ratings service and related software licensing revenue	82.00%	81.00%	89.00%	89.00%