Revenues by Revenue Sources (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenue [Line Items]      
Total Revenue $ 182,644 $ 152,550 $ 132,794
Partner and Other Revenue Sources      
Revenue [Line Items]      
Total Revenue 171,314 141,617 121,904
Proprietary Web site Traffic Sources and Domain Names      
Revenue [Line Items]      
Total Revenue $ 11,330 $ 10,933 $ 10,890