Schedules of Concentration of Risk Based on Accounts Receivable (Detail) (Consolidated Accounts Receivable)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Advertiser A
   
Concentration Risk [Line Items]    
Concentration Risk, Percentage 41.00% 41.00%
Advertiser B
   
Concentration Risk [Line Items]    
Concentration Risk, Percentage    [1] 14.00%
Advertiser C
   
Concentration Risk [Line Items]    
Concentration Risk, Percentage    [1] 13.00%
Advertiser D
   
Concentration Risk [Line Items]    
Concentration Risk, Percentage 16.00%    [1]
[1] Less than 10%.