Annual report pursuant to Section 13 and 15(d)

Key Estimates and Assumptions used in Start-Up Income Valuation of Broadcast Units For Each Testing Period (Detail)

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Key Estimates and Assumptions used in Start-Up Income Valuation of Broadcast Units For Each Testing Period (Detail) (Goodwill-Broadcast)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Schedule Of Goodwill And Intangible Assets [Line Items]      
Discount rate 9.00% 9.00% 9.00%
Minimum
     
Schedule Of Goodwill And Intangible Assets [Line Items]      
Operating profit margin ranges 5.10% 3.80% 3.80%
Long-term market revenue growth rate ranges 0.30% 1.00% 0.25%
Maximum
     
Schedule Of Goodwill And Intangible Assets [Line Items]      
Operating profit margin ranges 35.50% 38.00% 36.30%
Long-term market revenue growth rate ranges 15.00% 4.00% 3.50%