Basis of Presentation and Summary of Significant Accounting Policies (Tables)
 9 Months Ended
Sep. 30, 2012
Accounting Policies [Abstract]  
Business acquisition pro forma information
Supplemental information on an unaudited pro forma basis, as if the four acquisitions completed in 2011 had been consummated as of January 1, 2011 is as follows:

 
Three months ended September 30,
 
Nine months ended September 30,
 
2011
 
2011
 
(unaudited)
Revenue
$
82,198

 
$
244,710

Net loss
(4,484
)
 
(14,185
)
Financial assets and liabilities carried at fair value on a recurring basis
Financial assets and liabilities carried at fair value on a recurring basis were as follows:
 
December 31, 2011

 
 
Level 1
 
Level 2
 
Level 3
 
Total
Assets
 

 
 

 
 

 
 

Cash equivalents(1)
$
54,701

 
$
15,447

 
$
—

 
$
70,148

Total assets at fair value
$
54,701

 
$
15,447

 
$
—

 
$
70,148

___________________________________
(1)Comprises money market funds which are included in Cash and cash equivalents in the accompanying balance sheet

September 30, 2012

 
Level 1
 
Level 2
 
Level 3
 
Total
Assets
 

 
 

 
 

 
 

Cash equivalents(1)
$
29,126

 
$
7,939

 
$
—

 
$
37,065

Total assets at fair value
$
29,126

 
$
7,939

 
$
—

 
$
37,065

___________________________________
(1)Comprises money market funds which are included in Cash and cash equivalents in the accompanying balance sheet