Property and Equipment (Tables)
 9 Months Ended
Sep. 30, 2012
Property, Plant and Equipment [Abstract]  
Schedule of property and equipment
Property and equipment consisted of the following:
 
December 31,
2011
 
September 30,
2012
Computers and other related equipment
$
33,680

 
$
40,016

Purchased and internally developed software
45,074

 
52,616

Furniture and fixtures
2,380

 
2,610

Leasehold improvements
3,368

 
3,415

 
84,502

 
98,657

Less accumulated depreciation
(51,876
)
 
(64,917
)
Property and equipment, net
$
32,626

 
$
33,740
Schedule of depreciation and amortization
Depreciation and software amortization expense by classification for the three and nine months ended September 30, 2011 and 2012 is shown below:
 
Three months ended September 30,
 
Nine months ended September 30,
 
2011
 
2012
 
2011
 
2012
Service costs
$
4,112

 
$
3,587

 
$
12,305

 
$
10,789

Sales and marketing
109

 
105

 
296

 
345

Product development
399

 
234

 
1,158

 
787

General and administrative
683

 
906

 
2,133

 
2,703

Total depreciation
$
5,303

 
$
4,832

 
$
15,892

 
$
14,624